RCCL MAY 2016 REVIEW OF CORNEA & CONTACT LENSES COMPREHENDING KERATOCONUS The irregular cornea is seen more and more regularly than ever before. Our experts help to get you prepared.

Update on the Causes of Ectatic Disorders p. 10 Correcting Keratoconus With Contact Lenses p. 14 Crosslinking: Reshaping Keratoconus Management p. 20 Surgical Intervention for the Irregular Cornea p. 26

EARN 1 CE CREDIT What Corneal Shape Reveals

About Corneal Health Supplement to p. 30

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RCCL0416_Coopervision.indd 1 3/22/16 3:24 PM contents Review of Cornea & Contact Lenses | May 2016

departments features Bringing Clarity to 4 News Review Keratoconus Corneal Crosslinking for Pediatric Corneal thinning and its eff ects on Patients; Link Between Axial Myopia vision and eye health remains an and Keratoconus Questioned extremely complex topic; however, recent 10 consensus reports have helped to answer My Perspective some of the more vexing questions. 6 By Sheila D. Morrison, OD, MS Look Beyond the Slit Lamp By Joseph P. Shovlin, OD A Vision Correction Roadmap for Keratoconus The GP Experts Follow along as an expert explains how 7 to get these patients to 20/20. Steep Competition By S. Barry Eiden, OD By Robert Ensley, OD, and 14 Heidi Miller, OD

37 Practice Progress Corneal Crosslinking: Improve Your Contact Lens Fits Reshaping Keratoconus with Help from Your Staff Management By Mile Brujic, OD, and Jason R. Miller, These lenses are good for more than just OD, MBA the irregular cornea. Five cases illustrate 20 their potential. By Clark Y. Chang, OD

Surgical Management of Keratoconus: Battle of the Bulge Corrective lenses can serve patients well for years, but a lasting solution may 26 require a trip to the OR. By Soroosh Behshad, MD, Priscilla Q. Vu, and Marjan Farid, MD

ON THE COVER CE — What Corneal Shape A 57-year-old white male with advanced Reveals About Corneal Health keratoconus OU and central scarring as Mapping the a result of the condition. He presented irregular cornea wearing corneal GPs (parameters reveals much unknown), but complained that the about disease lenses dislodged very frequently. He was 30 status and its successfully fi t with a scleral lens and can amenability to now see 20/25 with that correction. treatment. Here’s Image and case courtesy of Stephanie a review. Woo, OD, Havasu Eye Center, Arizona By Randy Kojima and S. Barry Eiden, OD

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/ReviewofCorneaAndContactLenses @RCCLmag REVIEW OF CORNEA & CONTACT LENSES | MAY 2016 3

003_RCCL0516_TOC.indd 3 4/25/16 2:01 PM News Review

IN BRIEF Corneal Crosslinking Suitable ■ A clinical fi nding commonly seen in infectious etiologies or as a side eff ect of an allergic drug reaction may be a late-onset for Pediatric Patients indication of vernal keratoconjunctivitis, suggests a study published online in the journal Cornea.1 Researchers in Iran pre- pithelium-off corneal cross- cance during the one-year, two-year sented two case reports of Splendore-Ho- linking (CXL) is effective and three-year visits. CDVA also eppli phenomenon (a rare histopathologic condition associated with granulomatous in preventing worsening of improved similarly following the infl ammation), which were both treated keratoconus in pediatric procedure at all time points except using topical corticosteroids, as well as E cyclosporine 2% in one instance. patients; however, certain subtypes the fi ve-year-postoperative visit. “Our patients had distinct clinical of the condition may be predisposed Patients also demonstrated improve- features and extensive involvement of the upper bulbar conjunctiva. Based on the to continue progressing despite ment in both Kmax and Kavg values: histopathologic report, documented history treatment, reports a study pub- the former improved signifi cantly of VKC, negative results of other causes 1 and rapid response to corticosteroids, lished online in the journal Cornea. one year post-treatment with sig- Splendore-Hoeppli phenomenon could be Crosslinking—which increases the nifi cant improvement throughout considered as a late fi nding of VKC in our patients,” they conclude. production of noncovalent bonds the follow-up period. Kavg similarly 1. Soleimani M, Tabatabaei SA, Mirshahi R, et al. New between collagen fi brils to improve improved with levels reaching sig- fi nding in vernal keratoconjunctivitis: Splendore-Hoep- the rigidity of corneal collagen—has nifi cance at the three- and four-year pli Phenomenon. Cornea. 2016. [Epub ahead of print.] previously been demonstrated to follow-up visits. ■ Red-tinted contact lens wear may prevent the progression of kerato- “In our pediatric population, improve quality of life for patients with retinal conditions, suggests a study in the conus in adults.2-4 To date, however, epithelium-off crosslinking can April 2016 Optometry & Vision Science.1 no controlled trials have been con- be considered both apparently Researchers in Israel and the US retrospec- tively evaluated centrally-colored lenses ducted on the procedure’s long-term safe and effective, achieving stable on nine patients with severe photophobia safety and effi cacy in children. long-term results up to fi ve years,” related to pathological retinal conditions. Best-corrected visual acuity and contrast Researchers in the Netherlands the researchers report, adding that sensitivity (CS) were measured with and compiled data from patients under the prevalence of progression was without contact lenses, and eye move- ment for nystagmus and subjective visual age 18 who underwent an epitheli- higher in the pediactric cohort functioning were recorded. With lens wear, um-off CXL procedure for progres- considered than in previous studies mean binocular visual acuity improved from 6/45 to 6/40 and CS improved from sive keratoconus between January performed involving adults, suggest- 0.92 to 1.18 log units. Seven of the nine pa- 2010 and December 2013 at the ing crosslinking may have different tients also demonstrated an improvement of at least one line in BCVA. University Medical Center Utrecht. effects in different age groups. “Our study suggests that the use of The procedure was performed in ac- Additionally, “22% of the eyes [in red-tinted contact lenses with luminous transmittance of 13% to 17% not only sig- cordance with the Dresden protocol this study] had disease progression nifi cantly reduced photophobia in patients (30-minute isotonic ribofl avin soak- in terms of increased keratometry with retinal dystrophies but also led to a ing time, 30-minute UVA irradia- readings.” This was attributed to modest improvement in visual acuity and CS,” the researchers note. Though seem- tion, perpendicular emission plane, decentralized cone location, which is ingly minor for healthy patients, “a gain of 370nm at 3mW/cm2). Uncorrected in line with the fact that cone eccen- even a single line on a Snellen chart is a meaningful improvement in overall visual distance visual acuity (UDVA), tricity has been identifi ed as a major 4 performance for those with limited visual manifest refraction and Scheimpfl ug predictor of K outcome. RCCL potential.” max corneal tomography measurements 1. Severinsky B, Yahalom C, Sebok TF, et al. Red-tinted 1. Godefrooij DA, Soeters N, Imhof SM. Corneal contact lenses may improve quality of life in retinal were taken and a slit-lamp evalua- cross-linking for pediatric keratoconus: long-term diseases. Optom Vis Sci. 2016 Apr;93(4):445-450. results. Cornea. 2016. [Epub ahead of print.] Photo: Boris Severinsky, MOptom tion focusing on atopic/allergic eye 2. O’Brart DPS, Chan E, Samaras K, et al. A random- disease and eyelid abnormalities ized, prospective study to investigate the effi cacy was performed prior to the surgery of ribofl avin/ultraviolet A (370 nm) corneal collagen cross-linkage to halt the progression of keratoconus. and at one, three, six, 12, 24, 36, Br J Ophthalmol. 2011;95:1519-1524. 48 and 60 months post-operation. 3. Hersh PS, Greenstein SA, Fry KL. Corneal collagen crosslinking for keratoconus and corneal Fifty-four eyes of 36 patients were ectasia: one-year results. J Cataract Refract Surg. involved. 2011;37:149-160. 4. Wisse RP, Godefrooij DA, Soeters N, et al. A Results indicated that UDVA multivariate anaysis and statistical model for A red-tinted lens can counteract improved at all follow-up times predicting visual acuity and keratometry one year photophobia and improve VA. after crosslinking for keratoconus. Am J Ophthalmol. with the difference reaching signifi - 2014;157:519-525.

4 REVIEW OF CORNEA & CONTACT LENSES | MAY 2016

004_RCCL0516-News.indd 4 4/25/16 2:08 PM RRCCLCCL REVIEW OF CORNEA & CONTACT LENSES

11 Campus Blvd., Suite 100 Newtown Square, PA 19073 Telephone (610) 492-1000 Fax (610) 492-1049 Editorial inquiries: (610) 492-1006 Advertising inquiries: (610) 492-1011 Link Between Axial Myopia Email: [email protected]

EDITORIAL STAFF and Keratoconus Questioned EDITOR-IN-CHIEF Jack Persico [email protected] SENIOR ASSOCIATE EDITOR here may not be an associ- atoconus and the two other groups Aliza Becker [email protected] CLINICAL EDITOR ation between keratoconus lie mostly in the refractive and Joseph P. Shovlin, OD, [email protected] and higher levels of axial corneal parameters, with signifi cant ASSOCIATE CLINICAL EDITOR myopia, despite prior re- differences seen for SE, J , K , J Christine W. Sindt, OD, [email protected] T 45 m 45,c EXECUTIVE EDITOR search suggesting otherwise, reports and CCT,” the researchers report. Arthur B. Epstein, OD, [email protected] CONSULTING EDITOR a study published online in the jour- “Keratoconic eyes also had signifi - Milton M. Hom, OD, [email protected] nal Cornea.1 The connection was cantly deeper anterior chambers SENIOR GRAPHIC DESIGNER Matthew Egger [email protected] fi rst suggested in the 1970s as a way than the other two groups, but no GRAPHIC DESIGNER to explain the excessive degrees of signifi cant differences were seen for Ashley Schmouder [email protected] AD PRODUCTION MANAGER myopia seen following penetrating either lens thickness or lens power.” Scott Tobin [email protected] keratoplasty; it was later confi rmed These results confi rm that kera- BUSINESS STAFF by studies that identifi ed signifi cant toconus has a minimal infl uence on PUBLISHER axial elongation in patients with axial myopia and that its patholo- James Henne [email protected] REGIONAL SALES MANAGER keratoconus. Of note, however: gy is purely corneal in nature, the Michele Barrett [email protected] patients with emmetropic eyes were researchers add. Additionally, the REGIONAL SALES MANAGER Michael Hoster [email protected] typically used as the control groups increase in anterior depth might be VICE PRESIDENT, OPERATIONS during these studies, which may the result of combined thinning and Casey Foster [email protected] have led to bias.2-4 outward expansion of the cornea. EXECUTIVE STAFF Researchers in Belgium set out to “Clinically, these fi ndings may be CEO, INFORMATION SERVICES GROUP Marc Ferrara [email protected] repeat prior statistical analyses of important to better understand the SENIOR VICE PRESIDENT, OPERATIONS the corneal and noncorneal biome- refractive development in patients Jeff Levitz [email protected] SENIOR VICE PRESIDENT, try in keratoconic eyes and compare with keratoconus, as well as for lens HUMAN RESOURCES these values to those of healthy eyes power calculations in patients with Tammy Garcia [email protected] VICE PRESIDENT, with a range of refractions and to keratoconus, where axial length is CREATIVE SERVICES & PRODUCTION a subgroup of emmetropes. Two the most important factor for lens Monica Tettamanzi [email protected] VICE PRESIDENT, CIRCULATION hundred patients were divided into power,” they conclude. RCCL Emelda Barea [email protected] three groups: those with keratoco- CORPORATE PRODUCTION MANAGER 1. Rozema JJ, Zakaria N, Hidalgo IR, Jongenelen John Caggiano [email protected] nus, those with healthy corneas and S, Tassignon M, Koppen C. How abnormal is the noncorneal biometry of keratoconic eyes? Cornea. a subset of the latter with emme- 2016. Epub ahead of print. EDITORIAL REVIEW BOARD Mark B. Abelson, MD tropic eyes characterized by a spher- James V. Aquavella, MD ical equivalent refraction between Edward S. Bennett, OD CXL Approved in US Aaron Bronner, OD ±0.75D. Uncyclopleged refraction US-based corneal surgeons Brian Chou, OD Kenneth Daniels, OD was determined using an autorefrac- now have access to collagen S. Barry Eiden, OD tometer, while keratometry values crosslinking, following last month’s Desmond Fonn, Dip Optom M Optom FDA clearance of the KXL System Gary Gerber, OD were measured using Scheimpfl ug from Avedro for keratoconus. Robert M. Grohe, OD tomographer. The former was used Susan Gromacki, OD Three prospective, randomized, Patricia Keech, OD to calculate the SE and Jackson cyl- Bruce Koffler, MD controlled, 12-month trials showed Pete Kollbaum, OD, PhD inders J and J , while the latter was 0 45 a decrease in Kmax among treated Jeffrey Charles Krohn, OD patients; untreated eyes continued Kenneth A. Lebow, OD used to calculate the anterior kera- Jerry Legerton, OD tometry K and anterior corneal to progress. Kelly Nichols, OD m Robert Ryan, OD Jackson cylinders J0,c and J45,c. Axial Jack Schaeffer, OD length, as well as central corneal Charles B. Slonim, MD Advertiser Index Kirk Smick, OD thickness (CCT) and aqueous depth, Mary Jo Stiegemeier, OD CooperVision ...... Cover 2 Loretta B. Szczotka, OD were also measured. Michael A. Ward, FCLSA “As one would expect, the differ- Alcon ...... Cover 3 Barry M. Weiner, OD Menicon ...... Cover 4 Barry Weissman, OD ences between the group with ker-

REVIEW OF CORNEA & CONTACT LENSES | MAY 2016 5

0004_RCCL0516-News.indd04_RCCL0516-News.indd 5 44/25/16/25/16 2:082:08 PMPM My Perspective By Joseph P. Shovlin, OD

Look Beyond the Slit Lamp Are you doing everything you can to make life easier for your keratoconus patients?

his month’s issue of plurality demonstrating a signifi cant from a mental health professional, Review of Cornea & decline further on.3 as comorbidity beyond mental Contact Lenses high- health is not uncommon. I recently lights the trials and MAKING A DIFFERENCE sent a patient with keratoconus Ttribulations of managing Where then, does advocacy fi t and a common case of eyelash patients who have keratoconus or in? Support groups for keratoco- ptosis/fl oppy eyelid syndrome for another corneal thinning disorder. nus patients include the National polysomnography; results from the This group of patients needs our Keratoconus Foundation and pulmonologist demonstrated the support not only from a clinical Global Keratoconus Foundation. presence of severe sleep apnea. For perspective, but also in the area of Both organizations provide resourc- patients who suffer from severe patient advocacy. Though a simple es such as written materials for eye ocular allergy—a source of misery concept in theory, to properly advo- care practitioners and information unto itself and also a potential con- cate for this group of patients, we for patients. tributor to keratoconus progression need to understand the factors that Another resource, the if excessive eye rubbing occurs—we affect their lives beyond what we see International Keratoconus can help manage their experience of at the slit lamp. Academy—a recently-founded orga- atopy with appropriate referrals. Several quality-of-life studies have nization for eye care professionals— Additionally, don’t forget the back demonstrated just how severely also offers an array of professional of the eye—the retina must also these patients’ lives are impacted.1,2 education and scientifi c develop- receive special attention. A dispro- Lower quality-of-life scores on the ment on this topic. According to portionate number of our CLEK NEI tool in keratoconic patients Barry Eiden, OD, the organization’s patients had one or more retinal correlated with binocular visual acu- cofounder and president: “Our breaks. Without a doubt, I can say ity worse than 20/40.1 Additionally, mission is to promote and develop I’ve seen more asymptomatic retinal steep keratometric readings (greater the knowledge of keratoconus and breaks in this group of patients than than 52D) were associated with other forms of corneal ectasia, and any other. lower scores concerning mental further promote the awareness health, ocular pain tolerance and and understanding of the most hether you see a large number driving ability.1 appropriate and effective treatment Wof keratoconic patients or just Unsurprisingly, patient vision in strategies for the management of a handful, be prepared to address the best eye is the most signifi cant these diseases.” Those interested the totality of this group’s needs. predictor of quality-of-life scores.2 in further information can visit the They rely on you not only for Additional fi ndings demonstrate organization’s website at www. exceptional eye care, but also as a that patients in this group also have keratoconusacademy.com. resource to help them cope with the between category three and category many non-ocular aspects of their four age-related macular degenera- STRENGTH IN NUMBERS life that are compromised by the tion (AMD), and that overall ocular I’m constantly reminded that we disease. Why not start by enrolling pain was worse than AMD scores. play a personal and vital role in the in the International Keratoconus “Keratoconus is a disease of management and support of every Academy and attempting to become relatively low prevalence that rarely single patient we see daily. Having a more effective advocate? See results in blindness,” one group seen keratoconus and other ectasia where it gets you—and them. RCCL concluded, “but because it affects patients in my practice for over 30 1. Kymer SM, Walline JJ, Zadnik K. et al.: Quality of young adults, the magnitude of its years, I can’t think of another group Life in Keratoconus. Am J Ophthalmol. 2004; Oct. public health impact is dispropor- that would benefi t more from our 138(4):527-35. 2. Kurma SA, Altun A, Gencaga T, et al. Vision Relat- tionate to its prevalence and clinical advocacy and support than this one. ed Quality of Life in Patients with Keratoconus. J of severity.”1 This decline in quality For instance, patients with thin- Ophthalmol. 2014. 3. Kymer SM, Walline JJ, Zadnik K, et al. Am J Oph- of life continues over time, with a ning disorders may need counseling thalmol. 2008; 145(4): 611-17.

6 REVIEW OF CORNEA & CONTACT LENSES | MAY 2016

0006_RCCL0516_MP.indd06_RCCL0516_MP.indd 6 44/25/16/25/16 2:182:18 PMPM The GP Experts By Robert Ensley, OD, and Heidi Miller, OD

Steep Competition With so many lens options, what should you choose to manage keratoconus? Take a look.

ue to recent improve- Source: GPLI ments in technology, Table 1. 2015 GP Lens Rx Rates for Keratoconic Eyes scleral lenses are used 7% TORIC more than ever to Dmanage patients with 9% HYBRID irregular corneas, including presen- 11% CORNEAL RESHAPING LENS tations of keratoconus and other corneal ectasias. In moderate-to-ad- 11% MULTIFOCAL vanced cases of keratoconus, a 14% NON-SCLERAL GP FOR THE IRREGULAR CORNEA scleral lens may be required to help with lens centration. 20% SCLERAL Scleral lenses also accommodate CONVENTIONAL SPHERICAL GP 43% corneas that are too steep to fi t with corneal GP lenses or those 0% 5% 10% 15% 20% 25% 30% 35% 40% 45% 50% that may have failed with other modalities.1 Vaulting the cornea of increasing current and future clearance, apical touch and three- minimizes risk of central scarring growth over traditional corneal GP point touch. Apical clearance pro- that can result from a poorly fi tting lenses for patients with keratoco- vides central vault over the apex of corneal lens. nus. Trailing behind was the use of the cornea with support of the lens Although scleral lenses are a intralimbals, hybrids, custom soft bearing on the paracentral cornea. wonderful option, it is important and piggyback lens designs.2 This strategy is not commonly used to keep in mind the associated Let’s now consider a few modali- due to reports of reduced visual risks that may present with its use. ties to better understand their roles. acuity and risk for dimple veiling. There is still a large amount of ev- This condition results from bubbles idence-based research necessary to SMALL DIAMETER GPs entering underneath the lens that determine the long-term side effects Gas permeable contact lenses lead to excessive tear pooling that of scleral lens wear. The question is, continue to be the most commonly compresses against the cornea to however, should all patients be fi t used contact lens type in kerato- create divots. These bubbles can with scleral lenses? Is this arguably conus management.3,4 GP contact result in glare or reduced vision. the new standard of care for this lenses mask irregular astigmatism Apical touch places all lens condition? to provide a more uniform ante- support on the apex of the cornea, As part of the 2015 Gas rior refractive surface. They also creating a zone of bearing on fl uo- Permeable (GP) lens annual report, provide good tear exchange, but rescein assessment. Patients report 180 doctors were asked about their may be initially uncomfortable due good visual acuity; however, there GP lens prescribing habits, report- to lid interaction with the edge of may be an increased risk of corneal ing that though the majority of the lens. In mild cases, soft contact scarring with fl at fi tting lenses. One their fi ts were spherical lenses, one lens or spectacle wear may suffi ce; study demonstrates similar wearing in fi ve lens fi ts were achieved using however, as the condition progress- comfort with both apical touch scleral lenses (Table 1). Additional es, GP lenses are generally required and apical clearance lens fi tting results reported scleral lenses were to correct the irregular astigma- methods.5 The three-point touch prescribed almost as often as cor- tism. Often, a corneal GP lens is fi tting method allows the contact neal GP designs, with 50% of total used unless centration or comfort lens to bear lightly on the apex of fi ts being corneal GP designs and is compromised, or another lens the cornea, with heavier bearing 44.7% of total fi ts being sclerals. modality proves more useful. on the paracentral cornea. This Interest in vaulting strategies Three types of fi tting relationship technique is associated with good also continues to represent an area exist for corneal GP lenses: apical visual acuity.

REVIEW OF CORNEA & CONTACT LENSES | MAY 2016 7

007_RCCL0516_GPE.indd 7 4/25/16 2:03 PM The GP Experts By Robert Ensley, OD, and Heidi Miller, OD

Case Report: How Allergy Can Infl uence the Course of Keratoconus

hough keratoconus has long Case in Point. A 14-year-old The patient presented with the Tbeen classifi ed as a non-in- Hispanic male presented to the following spectacle correction: fl ammatory disease with a vari- clinic with reduced vision in his OD: -3.75 -7.75 x 013 with DVA ety of genetic and enviromental right eye that was uncorrectable 20/500, PH 20/100 and VVA RS200 factors, recent research has to 20/20 with spectacle lenses. OS: -400 DS with DVA 20/20-2 demonstrated increased infl am- He reported wearing spectacle and NVA RS20-2 matory mediators in the tears of correction for myopia since age Corneal topography revealed an keratoconic patients, suggesting fi ve, but had noticed the degrada- asymmetric bowtie with irregular the pathogenesis of progression tion in vision quality in the last two astigmatism and inferior steep- may involve chronic infl ammato- years. Patient history indicated he ening present in both eyes. The ry events.8-12 As such, it may be had been diagnosed with kerato- overall presentation was worse in appropriate to consider kerato- conus at his previous comprehen- the right eye vs. the left (Figure 1). conus as an infl ammatory-related sive eye examination and noted a Mire distortion was evident during condition.13 Abnormal eye rubbing habit of eye rubbing due to ocular the patient’s corneal topography secondary to ocular allergic con- itching with no history of contact evaluation. His best-corrected ditions is a commonly proposed lens wear. The patient’s systemic spectacle distance visual acuity pathogenetic factor in for kerato- history was unremarkable, as was in the right eye was 20/150 and conus, as the action instigates the his family’s systemic and ocular 20/20+2 in the left eye. Pinhole release of infl ammatory mediators medical history. He denied taking did not improve his vision in the that may alter the corneal collagen any medications or having aller- right eye. Additionally, a biomi- and lead to corneal ectasia.14 gies to medications. croscopy examination revealed the presence of Fleischer’s ring in his right cornea and Vogt’s striae in both. No other slit lamp fi ndings commonly associated with kerato- conus like stromal thinning, apical scarring or Munson’s sign were noted. No signs of ocular allergy were noted. An examination of the remainder of the anterior segment was unremarkable. The patient was fi t using a corneal GP lens from a fi tting Fig. 1. Axial map at baseline. set that was designed based on the Collaborative Longitudinal Evaluation of Keratoconus study. The diagnostic lenses used were a tricurve design with an overall diameter of 8.8mm with base curve radii ranging from 7.18mm to 4.50mm and variable optic zone diameters that decrease in size as the base curve steepens. The con- tact lens powers are variable to provide low minus over-refractions for most of the mild-to-moderate keratoconic patients.12 The sec- Fig. 2. Fluorescein pattern of fi nalized GP contact lenses. ondary curve is 8.50mm for each

8 REVIEW OF CORNEA & CONTACT LENSES | MAY 2016

007_RCCL0516_GPE.indd 8 4/25/16 2:03 PM HYBRIDS and 9 o’clock corneal staining, a SynergEyes Ultrahealth is a piggyback soft lens may be the best lens, based on corneal curvatures hybrid lens specifi cally designed solution to provide protection to beyond the cone being similar to for keratoconic patients. When the cornea. the corneal curvatures of patients without keratoconus.12 The center fi t properly, these lenses vault the thickness for all lenses is 0.14mm. corneal apex to inhibit movement, n summary, it is important to One drop of proparacaine 0.5% minimizing mechanical interactions Ilook at all the available options ophthalmic solution was instilled that could lead to scarring. These and decide when each is best for a in each eye to alleviate initial lens lenses also provide adequate given patient, taking into account awareness during the contact lens oxygen supply to the cornea. both the severity of the condition fi tting. Over-the-counter Alaway With hybrid lenses, there is a tear and fi nancial circumstances. In (ketotifen, Bausch + Lomb) was pump under the lens as evidenced some cases, it may still be best to also prescribed for use twice a by the loss of sodium fl uorescein stick to traditional treatment meth- day in both eyes. No ocular aller- 6 underneath the lens over time. The ods. RCCL gy signs were noted at the time beauty of hybrid lenses is that the of the exam, though allergy drops 1. Segal O, Barkana Y, Hourovitz D, et al. Scleral were recommended for prophy- GP center offers optimized vision, contact lenses may help where other modalities while the soft silicone hydrogel fail. Cornea. May 2003;22(4):308-310. lactic use to minimize future rub- 2. Bennett ES. GP Annual Report 2015. Contact bing. Preservative-free artifi cial skirt centers the lens over the Lens Spectrum. 2015;30(October 2015):24-27, cornea to allow for longer-lasting 29-31. tears were also prescribed to be 3. Zadnik K, Barr JT, Edrington TB, et al. Baseline taken as necessary. comfort. Also, the GP center fi ndings in the Collaborative Longitudinal Evalua- tion of Keratoconus (CLEK) Study. Invest Ophthal- Results. After a few follow-up delivers a UVA and UVB blocker to mol Vis Sci. Dec 1998;39(13):2537-2546. visits and minor adjustments to protect eyes from the sun. Hybrids 4. Lim N, Vogt U. Characteristics and functional outcomes of 130 patients with keratoconus attend- the peripheral curves, the pa- are suitable as a fi rst-line therapy ing a specialist contact lens clinic. Eye (Lond). Jan tient’s contact lenses were fi nal- for mild-to-moderate keratoconic 2002;16(1):54-59. ized. Fluorescein pattern assess- 5. Edrington TB, Gundel RE, Libassi DP, et al. patients. Variables aff ecting rigid contact lens comfort ment demonstrated fl uff y central in the collaborative longitudinal evaluation of apical touch, with mid-peripheral keratoconus (CLEK) study. Optom Vis Sci. Mar PIGGYBACK LENSES 2004;81(3):182-188. pooling in the right eye (Figure 6. Lee KL, Nguyen DP, Edrington TB, Weissman 2). No bubbles were noted under- Piggyback systems consist of a BA. Calculated in situ tear oxygen tension under hybrid contact lenses. Eye Contact Lens. Mar neath the lens. The lens decen- corneal GP lens fi t over a highly 2015;41(2):111-116. tered slightly inferiorly, but was oxygen permeable, low-powered 7. Michaud L, Brazeau D, Corbeil ME, Forcier P, Bernard PJ. Contribution of soft lenses of various picked up with a blink. There was soft contact lens. Low-powered powers to the optics of a piggy-back system on 360 degrees of average peripher- lenses are typically used due to regular corneas. Cont Lens Anterior Eye. Dec 2013;36(6):318-323. al edge clearance when the lens their marginal 20% contribution 8. Krachmer JH, Feder RS, Belin MW. Keratoconus was centered on the eye. There and related noninfl ammatory corneal thinning dis- of marked lens power towards the orders. Surv Ophthalmol. Jan-Feb 1984;28(4):293- was minimal lens movement optics of the lens system.7 However, 322. on blink; however, movement now that several other options exist 9.Cristina Kenney M, Brown DJ. The cascade was not a concern due to lack hypothesis of keratoconus. Cont Lens Anterior Eye. to manage corneal GP lens intoler- Sep 2003;26(3):139-146. of corneal staining. The left lens 10. Vazirani J, Basu S. Keratoconus: current demonstrated an alignment fi t ance, piggyback lenses are not often perspectives. Clinical Ophthalmology. 2013;7:2019- used, though they can be a good 2030. centrally with pooling noted su- 11.Nowak DM, Gajecka M. The genetics of keratoco- periorly at the edge of the optic option for centration and stabi- nus. Middle East African Journal of Ophthalmology. lization of GP lenses. They also Jan 2011;18(1):2-6. zone but decentered slightly infe- 12. Rabinowitz YS. Keratoconus. Surv Ophthalmol. rior temporally. The lens provided provide added comfort for those Jan-Feb 1998:42(4):297-319. adequate movement on blink, and suffering from corneal GP lens 13. Lema I, Duran JA. Infl ammatory molecules in the tears of patients with keratoconus. Ophthalmology. peripheral edge clearance was discomfort by minimizing mechan- Apr 2005;112(4):654-659. minimal at 9 o’clock and average 14. Sharma N, Rao K, Maharana PK, Vajpayee RB. ical eyelid interaction with the GP Ocular allergy and keratoconus. Indian J Ophthal- at 3, 6 and 12 o’clock. lens edge. For those who exhibit 3 mol. Aug 2013;61(8):407-409.

REVIEW OF CORNEA & CONTACT LENSES | MAY 2016 9

007_RCCL0516_GPE.indd 9 4/25/16 2:03 PM Bringing Clarity to KERATKERATOCONUSOCONUS

Corneal thinning and its eff ects on vision and eye health remains an extremely complex topic; however, recent consensus reports have helped to answer some of the more vexing questions.

By Sheila D. Morrison, OD

he visual consequences of Common clinical fi ndings in pa- decade of life.1 Mandatory clinical keratoconus—which has tients with post-refractive ectasia fi ndings to diagnose keratoconus TThistorically been defi ned include a thicker resulting fl ap or include abnormal posterior ectasia, as a noninfl ammatory condition thinner residual stromal bed than in addition to corneal thinning and with hallmark progressive corneal expected. However, post-refractive abnormal corneal thickness distri- thinning and steepening.—can be surgery ectasia can still occur in bution.1-2 According to the Global devastating for many patients.1 the absence of these fi ndings.1-6 Consensus on Keratoconus and Corneal ectatic disorders often Overall, the prevalence of post-re- Ectatic Diseases, the pathophysiol- result in decreased acuity, in- fractive surgery ectasia is estimated ogy of the condition likely includes creased ocular aberrations and, in to be between 0.2% and 0.66%.1-6 genetic, biochemical, biomechan- some cases, the need for surgical Forme fruste (i.e., subclinical) ical and environmental compo- intervention.1 keratoconus is an often-undi- nents, but has no primary patho- agnosed latent form of biome- logic explanation.2 Induced ectasia TYPES OF ECTASIA chanical instability in the cornea, may be unilateral or bilateral and Because ectasia describes a physi- which can be induced by refractive secondary to mechanical processes ological fi nding rather than a par- surgery and result in post-refrac- in a predisposed cornea.2 ticular disease process, it is used tive surgery ectasia.6,8-9 Other • Pellucid Marginal in the context of various clinical risk factors for iatrogenic corne- Degeneration. Considered the entities that can arise by mechani- al ectasia include thin baseline second most common form of cal, degenerative or genetic factors. cornea, irregular corneal thickness, ectatic disorders, pellucid marginal • Post-Surgical Ectasia. high myopia (due to the need for degeneration presents between the Iatrogenic ectasia can occur an increased amount of ablated third and fi fth decade of life.1 It is post-laser-assisted in situ ker- tissue) and young age at the time characterized by inferior peripheral atomileusis (LASIK) or after a of refractive surgery.10 In all cases, corneal thinning and a ‘bow-tie’ photorefractive keratectomy unilateral presentation of kerato- topographical map appearance of (PRK) procedure.1-2 Additionally, conus contraindicates surgery for the cornea. small-incision-lenticule extraction the other eye because keratoconus (SMILE) is a relatively novel is currently understood to be a ABOUT THE AUTHOR refractive procedure that uses a bilateral disease.1-4 Dr. Morrison is the cornea femtosecond laser to remove a • Keratoconus. Considered to be and contact lens resident disc-shaped portion of stroma with the most common form of ectatic at Pacifi c University College of Optometry. no fl ap lift, achieving similarly suc- disorder, primary keratoconus She specializes in medical cessful results to those of LASIK. affects at least one out of every contact lenses and has a current research interest In two recent isolated case reports, 2,000 members of the general in gas permeable contact ectasia following this procedure population.1-3 Usually, keratoco- lens design, scleral shape and contact lens solutions. was documented.11,12 nus presents in the second or third

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010_RCCL0516_F1_Causes-of-Keratoconus.indd 10 4/25/16 2:03 PM • Keratoglobus. A rare corneal thinning disorder that is char- acterized by general thinning and protrusion of the cornea. Keratoglobus may be present early in life, or may be acquired.1 Like primary keratoconus, the patho- physiologic and genetic etiology of pellucid marginal degeneration and keratoglobus remains unclear. Today, the majority of patients Anterior chamber segment optical coherence tomography image of thin, with keratoconus or other forms of ectatic cornea in post-LASIK ectasia. corneal ectasia are managed with specialty contact lenses, such as corneal or scleral rigid gas perme- able lenses, rather than surgery. As such, optometrists trained in medi- cal contact lenses are often the fi rst line of care for this affected popu- lation. Being knowledgeable about the causes of these conditions can help to enable better clinical Central 9mm segment optical coherence tomography image of thin, decisions and increase the ease of protruding cornea in keratoglobus. The central caliper measure of corneal thickness is 145µm. delivering patient education. fl ammatory and anti-infl ammatory It does appear, however, that a BIOCHEMICAL INFLUENCES cytokinesas well.1,16 Aquaporins positive family history for kera- Our knowledge about the causes are cell membrane proteins that toconus is a risk factor for devel- of ectasia has come a long way act as critical water channels for opment of the disease, indicating since the condition’s discovery, cells, and have been reported to a possible familial inheritance.18 largely because of advances in be defi cient in the epithelium of Studies have estimated relatives of the way we measure the structure keratoconic corneas.38 those with keratoconus to have a and composition of the cornea. risk of 15 to 67 times greater than Essentially, corneal thinning in ker- GENETICS those with no family history of atoconus occurs when corneal col- Despite decades of research on the keratoconus.25 A recent support- lagen degrades.1,3 It has been sug- possible genetic causes of kerato- ed hypothesis also suggests that gested that this degradation could conus, its pathogenesis and associ- consanguinity is a signifi cant risk be related to alterations in enzyme ation with other diseases remains factor for keratoconus.31 However, activity from normal levels; for poorly understood.3,18 to the best of our current knowl- example, matrix metalloproteinase Support for the potential of ge- edge, there are no direct genetic (MMP) levels have been shown to netics or the environment playing a causative factors identifi ed yet. be elevated in keratoconic corneas, role in the progression of keratoco- Interestingly, keratoconus can demonstrating a possible role for nus has been introduced by a series develop in the absence of certain these enzymes in collagen degra- of twin studies describing cases in conditions or in the presence of dation.3,12-14 Increased expression which both siblings are affected.3,19 others. The medical literature of MMPs is widely observed in However, not all twin studies documents associations between human tissue in which infl amma- demonstrate evidence of both indi- the disorder and Down syndrome, tion is present.15 Elevated levels of viduals developing keratoconus.3,20 Marfan syndrome, Ehlers-Danlos other infl ammatory mediators like Additionally, some linkage studies syndrome and Leber congenital interleukin-6 and tumor necrosis report genetic susceptibility related amaneurosis.1-3,17-18 These correla- factor-α have also been found in to gene mutation, while others tions could be postulated to relate the tears of keratoconus patients have found no link between kera- to the eye rubbing behavior or and an imbalance between pro-in- toconus and mutated genes.18,22-24 connective tissue defi ciencies that

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010_RCCL0516_F1_Causes-of-Keratoconus.indd 11 4/25/16 2:03 PM BRINGING CLARITY TO KERATOCONUS

funcion.32 Equally important was the fi nding that because of the ad- verse effects poor vision can have on daily functionality, keratoconus patients who wear contact lenses (i.e., mostly rigid gas permeable lenses) generally have better scores on mental health and function- ality measures than keratoconus patients who do not wear contact lenses.32 Left: Topography pattern showing inferior corneal steepening in keratoconus. As noted above, eye rubbing Right: Topography pattern showing irregular astigmatism over the visual axis can trigger unilateral or bilateral in post-LASIK ectasia. induced keratoconus, a cause- and-effect relationship in which commonly accompany many of especially those that are inhaled or mechanical friction on the cornea these conditions.17 ingested. An allergy is defi ned as a causes oxidative stress and the pro- Thinning of other connective chronic condition that involves an duction of damaging free radicals tissues of the body is not typically abnormal reaction to an ordinarily within the corneal tissue which seen in keratoconus patients, how- harmless substance that functions may result in corneal thinning.30,36 ever; the landmark Collaborative as an allergen for that individual. This has been documented in Longitudinal Evaluation of In an allergic reaction, the immune repeated case reports in which Keratoconus (CLEK) Study indi- system views an allergen as an in- patients who rubbed their eyes for cates no association with connec- vader and directs white blood cells reasons including ocular allergy, tive tissue disease.32 to produce IgE antibodies, which atopy, compulsive or nervous per- attach themselves to mast cells to sonality disorder, punctal agenesis OXIDATION trigger a release of potent chemi- (and subsequent chronic watery It is known that the cornea metab- cals like histamine.29 eye), stress or dry eye subsequently olizes oxygen to support its phys- Research suggests prevalence developed keratoconus.1-3,30,32-36 iologic processes.17 Keratoconic of keratoconus is associated with As such, it is the responsibility corneas have been found to exhibit atopic disease and ocular aller- of eye care practitioners to keep a decrease in levels of antioxidant gy.1-3 Though there is evidence to modifi able risk factors in mind enzymes such as glutathione, suggest atopy may contribute to and educate all patients about the which are involved in the break- keratoconus, the association is adverse effects of such behaviors. down and elimination of reactive most likely due to the tendency of If possible Photo: Patrick Caroline, Pacific University College of Optometry oxygen species.17,26-27 Relevant to patients with atopy and/or allergy it may also keratoconus progression, several to chronically rub their eyes to re- be necessary factors discussed in the literature lieve irritation.2,30 As such, from a to educate that may lead to oxidative dam- treatment standpoint, patients with family age of corneal tissue—specifi cally, coexistent keratoconus and atopic members or the stroma and Bowman’s mem- disease should be managed cooper- care provid- brane—are atopy, mechanical atively by an eye care provider and ers about trauma and exposure to ultraviolet immunologist. the impor- radiation.28 • Mechanical Insult. The CLEK tance of • Atopic Disease and Ocular Study, which evaluated the connec- eliminating Allergy. Atopy is defi ned as the tion between contact lens fi tting eye rubbing, genetic predisposition to develop techniques, apical changes and as many allergic diseases like allergic rhini- scarring in keratoconus, suggested patients will tis, asthma and atopic dermatitis that contact lens wear may be a rub their (i.e., eczema). Atopy is typically as- risk factor for increased corneal eyes habit- sociated with heightened immune scarring, implying that inadequate ually and Anterior segment responses to common allergens, lens fi t can negatively affect visual sometimes photo of keratoconus.

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010_RCCL0516_F1_Causes-of-Keratoconus.indd 12 4/25/16 2:03 PM 20. Bechera SJ, Shin JA, Newlin A, et al. Discor- without awareness that they are of keratoconus and other corneal dance for keratoconus in two pairs of monozy- doing so. ectasias will require continued gotic twins. Cornea. 1999;18:444-51. • Ultraviolet Light Exposure. research efforts by vision scientists 21. Fullerton J, Paprocki P, Foote S, et al. Identi- fy-by-descent approach to gene localization in Free radicals, a byproduct of oxi- and clinicians. RCCL eight individuals aff ected by keratoconus from dative stress, are formed with ex- north-west Tasmania, Austrialia. Hum Genet. posure to ultraviolet (UV) light or 1. American Academy of Ophthalmology Cornea/ 2002;110:462-70. External Disease Panel. Preferred Practice Pat- 22. Bisceglia L, De Bonis P, Campo PA, et al. Link- when mechanical insult occurs in a tern Guidelines. Corneal Ectasia. San Francisco, age analysis in keratoconus: replication of locus tissue. As compared to unaffected CA: American Academy of Ophthalmology; 2013. 5q21.2 and identifi cation of other suggested loci. Available at: www.aao.org/ppp. Invest Ophthalmol Vis Sci. 2005; 46:39-45. corneas, keratoconic corneas have 2. Gomes JA, Tan D, Rapuano CJ, et al. Global 23. Liskova P, Ebenezer ND, Hysi PG, et al. consensus on keratoconus and ectatic diseases. been found to have more damag- Molecular analysis of the VSX1 gene in familial Cornea. 2015;34(4):359-69. 37 keratoconus. Mol Vis. 2007;4:1887-91. ing byproducts. Additionally, ker- 3. Romero-Jimenez M, Santodomingo-Rubido atoconus prevalence and severity J, Wolff sohn JS. Keratoconus: A review. Contact 24. Tang YG, Picornell Y, Su X. et al. Three Lens & Anterior Eye. 2010;33:157-66. VSX1 gene mutations, L159M, R166W, H244R, are not associated with keratoconus. Cornea. has been reported as highest in the 4. Kanellopoulous AJ, Asimellis G. OCT corneal 2008;27:189-92. Middle East, though no sun ex- epithelial topographic asymmetry as a sensitive diagnostic tool for early and advancing keratoco- 25. Wang Y, Rabinowitz YS, Rotter JI, Yang H. posure study has been performed. nus. Clin Ophthalmol. 2014;18(8):2277-87. Genetic epidemiology study of keratoconus: ev- It is notable to consider the role 5. Rad AS, Jabbarvand M, Saifi N. Progressive idence for major gene determination. Am J Med of UV in the prevention of kera- kerectasia after laser in situ keratomileusis. J Genet. 2000;93:403-09. Refract Surg. 2004;20(5):718-22. 26. Gondhowiardjo TD, van Haerington NJ. toconus progression, as it is used 6. Said A, Hamade IH, Tabbara KF. Late onset Corneal aldehyde dehydrogenase, glutathione to activate ribofl avin for corneal corneal ectasia after LASIK surgery. Saudi J of reductase, and glutathione S-transferase in collagen crosslinking, which has Ophthalmol. 2011;25:225-30. pathologic corneas. Cornea. 1993;12:310-14. 7. Randeman JB, Russell B, Ward MA, et al. Risk 27. Behndig A, Karlsson GK, Johannson BO, et al. been shown to strengthen bonds in factors and prognosis for corneal ectasia after Superoxide dismutase isoenzymes in the human the cornea. LASIK. Ophthalmology. 2003;110:267-75. eye. Invest Ophthalmol Vis Sci. 1998;39:471-75. 8. O’Keefe M, Kirwan C. Laser epithelial ker- 28. Kenney MC, Brown DJ. The cascade hypoth- Keratoconus is historically atomileusis ectasia in 2010 – a review. Clin Exper- esis of keratoconus. Contact Lens Anterior Eye. thought to be a noninfl ammato- iment Ophthalmol. 2010;38:183-91. 2003;26:139-46. ry disease process that involves 9. Schweitzer C, Roberts CJ, Mahmoud AM, et al. 29. American Academy of Allergy, Asthma & Screening of forme fruste keratoconus with the Immunology. Conditions Dictionary. Available at: thinning of the cornea. However, ocular response analyzer. Invest Ophthalmol Vis www.aaaai.org/conditions-and-treatments/con- recent literature from a variety of Sci. 2010;51:2403-10. ditions-dictionary. 10. Moshirfar M, Edmonds J, Behunin N, Chris- 30. Bawazeer AM, Hodge WG, Lorimer B. Atopy sources suggests that due to in- tiansen SM. Corneal biomechanics in iatrogenic and keratoconus: a multivariate analysis. Br J creased MMP and other low-grade ectasia and keratoconus: A review of the litera- ture. Oman J Ophthalmil. 2013;6(1):12-17. Ophthalmol. 2000;84:834-56. infl ammatory markers, keratoco- 11. Sachdev G, Sachdev MS, Sachdev R, Gupta H. 31. Gordon-Shaag A, Millodot M, Essa M, et al. nus may have an infl ammatory Unilateral corneal ectasia following small-incision Is consanguinity a risk factor for keratoconus? lenticule extraction. J Cataract Refract Surg Optom Vis Sci. 2013;90:448-54. component that results in damage 2015;41(9):2014-18. 32. Wagner H, Barr JT, Zadnik K. Collaborative to the structural integrity of the 12. Maatta M, Vaisanen MR, Pihlajaniemi T, Tervo longitudinal evaluation of keratoconus (CLEK) cornea. Because of its noninva- T. Altered expression of type XIII collage in kera- study: methods and fi ndings to date. Contact toconus and scarred human corneas: increased: Lens & Anterior Eye. 2007;30:223-32. sive nature, tear fi lm analysis will increased expression in scarred human corneas 33. Batool J, Lichter H, Stulting R. Asymmetric remain a topic of great interest for is associated with myofi broblast transformation. keratoconus attributed to eye rubbing. Cornea. Cornea. 2006;25:448-53. 2004;23:560-64 the identifi cation of biomarkers 13. Sugar J, Macsai MS. What causes keratoco- 34. Kandarakis A, Karampelas M, Soumplis V et nus? Cornea. 2012;31:716-19. present to potentially aid in the al. A case of bilateral self-induced keratoconus 14. Balasubramanian SA, Pye DC, Wilcox MD. Are in a patient with Tourette syndrome associated etiology and early diagnosis of proteinases the reason for keratoconus? Invest 17 with compulsive eye rubbing: case report. BMC keratoconus. Ophthalmol Vis Sci. 2011;52:8592-7. Ophthalmology. 2011;11:28. 15. Parks WC, Wilson CL, Lopez-Boado YS. Matrix 35. Lindsay RG, Bruce AS, Gutteridge IF. Kerato- metalloproteinases as modulators of infl am- conus associated with continual eye rubbing due iscussion about possible mation an innate immunity. Nat Rev Immunol. to punctual agenesis. Cornea. 2000;19:567-69. relationships between kerato- 2004;4(8):617-29 D 36. Krachmer JH. Eye rubbing can cause kerato- 16. Albert SJ, Cope L, Speck C, et al. Subnormal conus and sleep apnea, diabetes or cytokine profi le in the tear fl uid of keratoconus conus. 2004;23:539-40. hormonal changes during pregnan- patients. PLoS ONE. 2011;6(1):e16437. 37. Kenney MC, Chwa M, Atilano SR et al. cy are also emerging in a number 17. Galvis V, Sherwin T, Tello A, et al. Keratoconus: Increased levels of catalase and cathepsin V/L2 an infl ammatory disorder? Eye. 2015;29:843-59. but decreased TIMP-1 in keratoconus corneas: of studies. It remains highly likely 18. Romero-Jimenez M, Santodomingo R, Evidence that oxidative stress plays a role in that there is a genetic predispo- Wolff sohn JS. Keratoconus: A review. Contact this disorder. Invest Ophthalmol and Vis Sci. 2005;46:823-32. sition to keratoconus, which can Lens Anterior Eye. 2010;33:157-66. 19. Weed KH, MacEwen CJ, McGhee CN. The 38. Rabinowitz YS, Wistow G. Gene expression be triggered by environmental variable expression of keratoconus within mono- profi le studies of human keratoconus cornea for zygotic twins: Dundee university Scottish kerato- NEIBank: a novel cornea-expressed gene and the factors related to oxidation. The conus study (DUSK). Contact Lens Anterior Eye. absence of transcripts for aquaporin 5. Invest progressive etiological elucidation 2006;29:123-26. Ophthalmol and Vis Sci. 2005;46:1239-46.

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0010_RCCL0516_F1_Causes-of-Keratoconus.indd10_RCCL0516_F1_Causes-of-Keratoconus.indd 1313 44/25/16/25/16 2:032:03 PMPM A Vision Correction Roadmap for KERATOCONUS

ost patients with over half a century. Though other for adequate tear exchange via keratoconus and options have been developed that appropriate peripheral edge other forms of cor- address the vision needs of the clearance. neal ectasia struggle keratoconic patient, these lenses Additionally, we need to Mto overcome visual still hold an important place in address the visual needs of our aberrations induced by irregulari- our contact lens armamentarium. keratoconic patients by not only ty of the anterior corneal surface. Advantages include good visual masking the anterior corneal Distortions induced by the irreg- rehabilitation via their ability to surface irregularity as completely ular posterior corneal surface and mask the anterior surface corne- as possible but also addressing visual limitations from corneal al irregularity, ease of handling, residual astigmatism. Often, we scar opacities within the visu- excellent tear exchange and see patients who present in their al axis in more advanced cases oxygenation of the cornea, low corneal GP lenses with limited are other contributing factors. rates of infectious keratitis and a acuity, only to fi nd that a cylin- Contact lenses function predom- decreased rate of infl ammatory drical overrefraction can improve inantly to address these visual changes. Primary disadvantages acuity by a number of lines. impairments in two ways: fi rst, by include initial and ongoing dis- When prescribing corneal GPs correcting traditional refractive comfort and awareness by many for keratoconus, practitioners can errors like myopia, hyperopia patients, debris and foreign body either custom design a lens or use and astigmatism (also known as accumulation under the lenses proprietary corneal GP designs lower-order aberrations) and, with associated discomfort and ir- specifi cally developed to address second, by masking the irregulari- ritation, diffi culty with centration the topographic requirements ty of the anterior cornea to create of the optics in highly decentered of the keratoconic cornea. As a a smoother and more regularly cone apices and the inability of general guideline, we suggest the shaped anterior optical surface, the lens to properly contour the following for corneal GP design which can signifi cantly reduce corneal surface without corneal selection for keratoconus: the visual distortions known as apical bearing in more advanced • When fi tting small central higher-order aberrations. cases of the disease. cones (i.e., nipple types), use For the most part, though, cur- Considerations when evaluat- small-diameter multicurve designs rent contact lenses do not address ing corneal GPs for keratoconus with overall diameters of less the residual distortion induced by include the location and size of than or equal to 9mm and optic irregularity of the posterior cor- cone, the shape and status of the zone diameters of less than or neal surface. This article will re- peripheral cornea and the fi nal equal to 7mm. view current contact lens options visual needs of the patient. Due • When fi tting moderately sized with emphasis on how to select to highly suggestive evidence and decentered oval cones, use the best modality in certain cases. that lens bearing on the apex of The advantages and limitations of the cone may increase the rate of ABOUT THE AUTHOR each will also be covered. scarring, apical bearing should Dr. Eiden is the president and be avoided as much as possible. medical director of North CORNEAL GAS We typically choose larger overall Suburban Vision Consultants and Keratoconus Specialists PERMEABLE LENSES lens diameters for corneas with of Illinois. He is also president and cofounder of Rigid corneal contact lenses have larger, decentered cones by fi rst the International Keratoconus been the gold standard of vision aligning the lens with the corne- Academy of Eye Care correction for keratoconus for al periphery and then allowing Professionals.

14 REVIEWREVIEW OOFF COCORNEARNEA & COCONTACTNTACT LENLENSESSES | MAY 2016

014_RCCL0516_F2_Roadmap-for-Fitting.indd 14 4/25/16 2:02 PM By S. Barry Eiden, OD

Follow along as an expert explains how to get these patients to 20/20.

moderate-diameter multicurve designs with overall diameters of 9mm to 11mm and optic zone diameters of 7.2mm to 9mm. Intermediate and peripheral curves can be spherical, aspheric or even toric if the peripheral cornea is regularly toric. • When fi tting large and highly decentered “globoid” and “pel- lucid-like” cones, use larger-di- ameter intralimbal designs with overall diameters of 11mm to 12.2mm (that typically measure 0.2mm less than the overall cor- neal diameter), along with larger optic zones (typically over 9mm). Patients wearing these designs Fig. 1. Scheimpfl ug tomography demonstrating regular astigmatism within can benefi t most from asymmetric the pupillary zone of a patient with keratoconus. BCVA with manifest refraction was 20/20-. However, should the power distribution within the peripheral geometries, in which pupillary zone appear to be signifi cantly irregular, one should expect peripheral curvatures can be reductions in best corrected manifest refraction acuity consistent with the varied along different quadrants degree of irregularity. or meridians. lens materials, scleral lenses have cornea or not—is to completely SCLERAL GAS PERMEABLE gained signifi cant popularity vault the cornea and land on CONTACT LENSES over the past decade. The general the bulbar conjunctival surface With the advent of highly ox- goal when fi tting a scleral lens overlying the sclera. Avoidance of ygen permeable gas permeable to virtually any eye—irregular corneal bearing, especially in the

Spectacles Can Still Play a Role

bove all, the primary goal for correcting vision in patients with keratoconus is to provide clear, Afunctional vision. There are many cases in which spectacles—the most classical form of vision cor- rection—provide excellent outcomes. One of the key diagnostic methods to achieve acceptable acuity with spectacles is to perform corneal topography and observe the power distribution within the pupil- lary zone. If that pattern is unremarkable in terms of its astigmatic profi le, one can expect the manifest refraction to result in good quality visual acuity, assuming that other elements of the ocular system are normal. Patient success with spectacle wear in cases of keratoconus is limited by various factors of the dis- ease, including adaptation to high astigmatism or signifi cant anisometropia, and frequent changes in refractive results in cases of progressive keratoconus. Practitioners should keep in mind, however, that even in cases in which contact lenses provide better correction for patients with keratoconus, specta- cles can still play a role, if only to allow for limited function when contact lenses are not actively being worn. All keratoconus patients should have a back-up pair of spectacles if possible.

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may be necessary. These are approximately the same size and fabricated from similar materials as scleral lenses, but are highly customized to address the unique and individual characteristics of more complex corneal cases. The Prosthetic Replacement of the Ocular Surface Ecosystem (PROSE) device by the Boston Foundation for Sight is one exam- ple; fi tting this device involves the use of proprietary diagnostic lens- es and a software program that measures the shape of the individ- ual patient’s ocular surface. Another example of a custom- Fig. 2. Placido topography demonstrating highly irregular astigmatism and tremendous power distribution within the pupillary zone of a keratoconic izable ocular prosthetic device patient. Best-corrected manifest refraction visual acuity was 20/60. is the EyePrintPro by EyePrint Prosthetics, an optically clear limbal area, is critical for success. those patients with compromised prosthetic scleral cover shell that Additionally, peripheral landing corneal endothelial function, such matches the contours of the eye should attempt to parallel the as those who have undergone to provide good vision and com- scleral surface without resulting penetrating keratoplasty. fort. When creating this prosthet- in conjunctival impingement/com- The scleral lens fi tting pro- ic, an impression is taken of the pression or signifi cant peripheral cess has advanced tremendously patient’s eye at the practitioner’s scleral lens lift or standoff. over the last few years, with the clinic, then shipped to EyePrint When appropriately fi t, these introduction of technologies Prosthetics to be digitized by specialty lenses provide excellent like anterior segment OCT and computerized topographical visual performance and comfort various forms of corneo-scleral scanners. Using three-dimensional independent of the degree of cor- profi le measurement instruments. scanning technology and comput- neal astigmatism. Scleral lenses The ability to “virtually” design er-controlled machining systems, can be designed in a variety of scleral lenses without a required an exact match is created to each sizes to accommodate a host of diagnostic lens evaluation and the individual cornea and sclera. In ocular shapes, and can be fabri- capacity to measure their physical effect, instead of using a series of cated to include anterior surface fi tting characteristics immediately standardized curvatures to create optics that address residual astig- following dispensing has reached the lens as is done with tradition- matism. Some are also available high levels of precision. When al scleral lenses, the EyePrintPro or are being developed in multifo- the degree of corneal and scleral is generated to exactly match the cal designs or to address residual surface irregularity is substantial unique irregularities of the indi- higher-order aberrations. enough to resist correction by vidual eye. Because of the precise Scleral lenses, however, are not even a vaulting scleral lens, an nature of the back surface fi t, a panacea. There are concerns ocular prosthetic scleral device high quality and individualized

regarding the oxygen transmis- Photo: Robert Davis, OD sion properties of these typically thick lenses, as they are fi t with signifi cant corneal vault and minimal tear exchange. We are still not certain what long-term physiological implications could be identifi ed after years of wear on diseased eyes, especially on Fig. 3. Model of a recessed pillow lens system.

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014_RCCL0516_F2_Roadmap-for-Fitting.indd 16 4/25/16 2:02 PM optics such as toric corrections, crisp optics of rigid lenses with up include improved initial and multifocals, high-order aberration the comfort of a hydrogel ma- ongoing patient comfort as com- correction and prismatic powers terial. A number of interesting pared with direct corneal rigid can be placed on the front surface approaches allow us to do just lens wear, potential reduction of of the device. that. mechanical physical compromise • Piggyback or Tandem to the ocular surface induced by COMBINING SOFT AND Contact Lens Systems. This ap- the corneal rigid lens and possible RIGID MATERIALS proach traditionally incorporates improvement of GP lens centra- Patients and practitioners alike a corneal gas permeable lens over tion for improved optics. The soft frequently prefer to combine the a soft lens. Advantages of this set- “carrier” portion of the system

Soft Lenses: Appropriate For Early to Moderate Cases

n the past, soft contact lenses had been consid- is the visual acuity outcome and visual stability Iered inappropriate for management of kerato- found from the SCOR. If vision is acceptable and conus, as these lenses drape over the irregular stable, results from SCOR can be incorporated corneal surface and conform to the anterior into a design. topography of the cornea. However, they may still When corneal irregularity is too high for tra- have certain indications in keratoconic patients: ditional soft lens designs to provide acceptable advantages include initial and ongoing comfort, vision quality, consider custom keratoconic soft ease of handling and care as well as a tendency to lens designs. These lenses address corneal irreg- maintain centration of the contact lens over the ularity by thickening the optic zone to mask the cornea and visual axis of the eye. Disadvantages condition. Central lens thickness values in these include the limited potential for addressing distor- applications can vary from approximately 0.35mm tion induced by irregular corneal optics, hypoxic to more than 0.60mm, depending on the degree sequelae and greater potential for infection and of corneal surface irregularity. Note, hypoxic infl ammation than rigid contact lenses. concerns due to increased lens thickness can be Traditional soft lens designs can be used in addressed with the following points in mind: keratoconus when the best-corrected manifest • Fit these lenses with signifi cant movement refraction visual acuity is acceptable and the de- (i.e., up to 1mm with blink) to allow for tear ex- gree of secondary visual distortion is limited. Just change with oxygenated tears. as with spectacle lens considerations, examining • Limit lens thickness increases to the optic the axial map in corneal topography can give the zone. Lenticularization can help keep peripher- practitioner a good idea of the patient’s visual al portions of the lenses thin. This is critical, as potential while wearing traditional soft lenses. oxygen transmission in the area of the highly Toric designs are often required due to the sig- sensitive limbal corneal stem cells is important for nifi cant amount of astigmatism typically present continued corneal health. in keratoconic patients; either planned replace- • Some of these designs can be manufactured ment, disposable designs or conventional annual with higher oxygen transmission SiHy materials replacement designs can be used. to off er added (albeit limited) benefi t, and more Lenses made from materials that allow higher designs will be available in this way over time. oxygen transmission like silicone hydrogels can be • Soft custom keratoconic lenses can also be worn to reduce the likelihood of hypoxic sequel- designed with front surface toricity to address ae, though non-silicone hydrogel materials have residual astigmatism. They may also have front been used with success for many years without surface aspheric optics that can minimize some hypoxic complications when proper design and of the residual higher-order spherical aberration fi tting strategies are considered. Additionally, found in keratoconic patients. giving special consideration to spherocylinder • Finally, the centration tendencies of these overrefraction (SCOR) with soft lenses is critically lenses are often advantageous in providing stable, important for visual performance; as such, it is centered optics. In some cases, however, the visu- not unusual to achieve results from SCORs that al axis is decentered from the corneal apex and, are not predicted by the original refractive data even in a well-centered lens, optical aberrations or the toric rotation marks on the lenses due to can be increased due to the mismatch of the vi- the unpredicted draping eff ects over a keratocon- sual and contact lens optics. Some custom design ic cornea. laboratories may be able to decenter the optic The key data to pay attention to, in this case, zone to address this issue.

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by the modulus of the material used. Higher modulus lenses may at times result in edge fl uting with associated lens awareness or discomfort. As such, high Dk/low modulus lens designs are often preferred. The fi tting methods of these systems are typically quite simple and result in use of GP lenses with the same fi tting and vision parameters as would be used when fi tting the GP lens directly on the cornea. The exceptions to this would be cases in which high-power soft lenses are used to infl uence lens centration. It has been estimated that only 20% of Fig. 4. An anterior segment optical coherence tomography scan of a scleral contact lens on the eye. the soft lens power manifests in a piggyback/tandem lens system; as provides assistance with GP lens the inherent diffi culty or inconve- such, since low power soft lenses centration (especially if higher nience of using such a system. are typically employed most, their plus power soft lenses are used, Today, the issue of corneal hy- infl uence on the total power of which create a relatively central poxia has been largely addressed the system is quite insignifi cant. steeper element to the anterior by the availability of multiple In addition to the use of con- ocular surface) and a barrier contact lens materials with high ventional disposable soft lenses against direct contact between the oxygen transmission properties. as a carrier for the GP lens in rigid lens and the ocular surface. Additionally, use of frequent piggyback/tandem lens systems, The GP lens portion of the replacement soft lenses (especially it is occasionally advantageous to system, meanwhile, provides daily disposable modalities) as consider custom soft lenses that the necessary optical correction. the base carrier in these systems have a recess or cut-out in the Any design and optical confi gu- means practitioners can provide anterior surface in which the GP ration of GP lens can be used in a more convenient and healthy lens can be placed. Recessed soft piggyback/tandem lens systems; option for piggyback/tandem lens lenses help better hold the GP however, disadvantages include wear as compared with options lens in place for optimal centra- potential limitation of oxygen in the past (Table 1). In cases of tion; as such, in this case, the soft transmission through the system corneal irregularity like kerato- lens provides the system’s centra- (depending upon lens material conus, the fi tting characteristics tion and movement, while the DK/t and thickness profi les) and of the soft lens may be infl uenced GP provides the optics. Examples

Table 1. Soft Lenses Typically Used in Piggyback/Tandem Contact Lens Systems

Design Dk/t Modulus (MPa) Replacement Frequency Night & Day 175 1.50 Monthly Acuvue Oasys 147 0.2 Two-Week Biofi nity 160 0.75 Monthly Ultra 163 0.70 Monthly Dailies Total 1 151 0.70 Daily MyDay 100 0.40 Daily AcuVue Oasys One-Day 121 0.96 Daily

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014_RCCL0516_F2_Roadmap-for-Fitting.indd 18 4/25/16 2:02 PM of recessed or cut-out soft lenses include the Flexlens Piggyback (X-Cel) and the Recessed Pillow Lens System (Fusion Technologies and EyeVis Vision Research). • Hybrid Contact Lenses. Based on the initial concept introduced by piggyback/tandem lens systems, hybrids are single lenses that com- Fig. 6. EyePrintPro impression and computer simulation. bine the attributes and advantages of both soft lenses and rigid gas movement during wearing time. It movement either initially or after permeable lenses. The Saturn lens, also provides acceptable comfort a period of wear. These issues are introduced in 1984, was the fi rst and good visual performance. An more commonly present when hybrid design; since then, vari- oblate design version of the lens, the cone is either too advanced ous developments in hybrid lens known as the UltraHealth FC, was in elevation or curvature and/ technology have led to the contem- also recently introduced. This re- or when the cone is signifi cantly porary version now manufactured verse geometry design is most ap- decentered. Thus a rule of thumb and distributed by SynergEyes. propriate for corneas characterized is that those cones that are mild Today’s hybrid lenses are fabri- by oblate topography, which is to moderate and more centralized cated from high oxygen transmis- most commonly found in patients tend to respond much better to sion materials and constructed to who have undergone refractive wear of vaulting hybrid contact avoid the fragility of the junction surgery or penetratingkeratoplasty. lenses. Optical limitations can also between the soft skirt and rigid However, some practitioners have present with hybrids when signifi - center of former hybrid designs. also used this design to successful- cant residual astigmatism is found Along with advances in materi- ly fi t certain cases of keratoconus due to the lack of availability of als and manufacturing improve- via incorporation of the more pro- anterior toric options at this time, ments, hybrid lens designs them- nounced reverse curve as a way to so this must also be kept in mind selves have also moved forward, “lift” the lens in order to achieve when evaluating a patient. with more indications than ever. adequate apical vault. This includes their use on irregular Contraindications for hybrid ll in all, keratoconus is a chal- corneas, with the most current lens wear for keratoconic patients Alenging disease that presents lens being the UltraHealth lens include scenarios in which ap- in a wide range of severity and (SynergEyes). The UltraHealth lens propriate physical fi tting char- visual disturbances. A detailed is a reverse geometry “vault” de- acteristics cannot be achieved understanding of the phenomenon sign confi gured to leap the apex of and thus results in one or more and extensive clinical experience the keratoconic cornea. When ap- of the following: apical bearing, in its management allows the propriately fi tted, the lens centers lens landing areas with excessive practitioner to tailor the most fairly well and maintains adequate bearing/compression or lack of appropriate vision correction solution for each patient. Contact lenses have been and continue to be the mainstay for this patient population; fortunately, both old and new lens options abound. Integrating the most appropri- ate contact lens treatment with a comprehensive medical and surgical approach will allow the keratoconic patient to receive the highest quality of care, which should result in optimal vision along with appropriate control of Fig. 5. A profi le view of a scleral lens on the cornea. the disease. RCCL

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This long-awaited procedure strengthens collagen bonds to stabilize the cornea. Recent technological advances seek to By Clark Y. Chang, OD make the treatment faster and more customizable.

eratoconus patients implemented around the world search fi ndings have also provided typically experience as a fi rst-line treatment for ker- insights into the implications of wide-ranging visual atoconus since the late 1990s redistributing biomechanical stress fl uctuations and dis- (Figure 1).3–6 Its ability to stiffen in the cornea, with the intention of ease progression from corneal tissue makes CXL the not only stabilizing the disease but K 10-13 onset, typically at puberty, until fi rst treatment to stabilize under- also normalizing corneal shape. the fourth decade of life, during lying stromal weakness and halt The stiffness of the human which the condition becomes or slow corresponding progres- cornea relies upon the lamellar or- relatively stabilized. Though sion of ectasia. Additionally, a ganization of the stromal collagen symptoms of visual aberrations are global Delphi panel comprised of fi bers, which are regulated by an unwelcome at any point during representatives from each of the interconnecting network of pro- one’s lifetime, the manifestations four supranational corneal societ- teoglycans.8 While there are still during these formative years are ies—the Asia Cornea Society, the unanswered questions about the especially inopportune. Cornea Society, EuCornea and precise combination of molecular, While refractive correction PanCornea—recently published a genetic and environmental factors with gas permeable contact lenses consensus report that recognized that contribute to the pathogenesis is often the standard of care in the importance of incorporating of keratoconus, it is believed that keratoconus, management during CXL as part of the new standard the interaction of these factors the condition’s progressive years of care in managing keratoconus leads to the loss or slippage of necessitates frequent contact lens and ectatic diseases.7 collagen fi brils and changes to the adjustments, resulting in a sig- extracellular matrix in the corneal nifi cant reduction in quality of CORNEAL BIOMECHANICS stroma.9 life and a substantial long-term INFLUENCE SHAPE Studies using x-ray scattering economic burden for affected pa- The ideal outcome for a patient techniques reveal a disorganiza- tients.1 According to conventional with keratoconus is to arrest the tion of the collagen lamellae in the evidence, up to 20% of cases may condition’s continual progression region of the cone, with a more go on to require penetrating ker- before visual function is com- normal organization of collagen atoplasty.2 To date, despite steady promised. Hence, the potential in the surrounding regions.10 advancements in contact lens tech- benefi ts of early intervention with While studies from the 1970s nologies, keratoconus still remains corneal crosslinking have sparked and 1980s revealed bulk abnor- the most common cause for such resurgent clinical interest in ex- malities in mechanical strength surgical intervention. ploring diagnostic instrumentation What if these patients could that could more easily allow for ABOUT THE AUTHOR have their vision stabilized years early disease detection. Dr. Chang is the director of clinical services at TLC Laser or even decades earlier? Such Recent investigative work in Eye Centers. He has been a is the game-changing potential the fi eld of corneal biomechanics subinvestigator in numerous clinical studies and has that corneal crosslinking (CXL) may hold the potential for earli- published extensively on represents. Despite having only er identifi cation of patients who keratoconus treatment. He is also an advisory board recently obtained FDA clearance could benefi t from CXL, and member of the International Keratoconus Academy for Eye Care in April 2016, CXL with ultra- could also aid in the analysis of Professionals (IKA), the Gas Permeable lens violet-A (UVA) and ribofl avin CXL outcomes to further improve Institute (GPLI), and the Optometric Cornea, photosensitizer has already been treatment parameters. These re- Cataract and Refractive Society (OCCRS).

20 REVIEW OF CORNEA & CONTACT LENSES | MAY 2016

020_RCCL0516_F3_CXL-Update.indd 20 4/25/16 2:02 PM a comprehensive assessment of CROSSLINKING corneal stress distribution would PARAMETERS IMPACT be essential to understanding the CLINICAL OUTCOME biomechanical factors at play in When crosslinking was fi rst intro- the progression of the ectasia and duced, a single treatment approach the effi cacy of treatment options. was applied in all cases. Termed Currently, two commercially “the Dresden protocol,” this con- available devices measure corneal ventional technique is performed biomechanical properties by ana- following removal of the central lyzing corneal behavior in response 7mm to 9mm of epithelium. The to a pulse of air. The Ocular stroma is saturated with ribofl avin Response Analyzer (Reichert) for 30 minutes, then irradiated measures the difference in tissue with 365µm UVA at 3mW/cm2 response between in- and outgoing for another 30 minutes for a total applanation pressures to provide UVA dose of 5.4J/cm2 (Figure 2). a measurement of energy loss due Additional ribofl avin drops are to viscous damping. This clinical instilled at fi ve-minute intervals Fig. 1. Peter Hersh, MD, of the Cornea parameter is represented as corneal during the irradiation phase.15 and Laser Eye Institute performing hysteresis (CH). Another device, Several randomized, controlled the conventional (i.e., Dresden) corneal crosslinking procedure. the CorvisST (Oculus), uses a high- trials have demonstrated statisti- speed Scheimpfl ug camera to eval- cally signifi cant improvement in

of keratoconic corneas relative to uate the deformation of the cornea maximum keratometry (Kmax) or normal eyes, more recent work in response to these pressures.14 cone apex power in CXL-treated based on biomechanical modeling Though both of these systems eyes compared with the untreated 16,17 and Brillouin optical microscopy provide information about the controls. Progression of Kmax further demonstrates that these overall biomechanical properties of of 2D or more has been observed abnormalities may be attributed the cornea, neither is able to map in 0% to 4.3% of CXL-treated to focal weakening over the region the regional differences in these eyes.16-18 A long-term study of of the cone, rather than across the properties. As such, the sensitivity patients treated with the conven- entire cornea.11-13 of the devices may be insuffi cient tional protocol reveals persistence The focalized reduction in elastic to diagnose early or forme fruste of the treatment effect through a modulus within the affected cor- keratoconus, due to the overlap in 10-year follow-up period.19 neal region deforms to a greater the range of values for normal and extent than the surrounding tissue weakened corneas. Additionally, when subjected to the strain of the the absence of spatial information normal intraocular pressure, mani- limits the applications of these festing in the conical protrusion. systems in determining focal weak- A proposed biomechanical cycle ening of the cornea or measuring of decompensation suggests that regional effects of corneal cross- the initial pathological changes linking within a treated cornea.14 triggered by genetic predisposition Several techniques are in devel- and environmental factors result in opment to address the potential this focal weakening of the cornea. benefi t of spatial measurement of The initial asymmetry in elastic corneal tissue properties, including modulus is thought to initiate a supersonic shear imaging, Brillouin cycle of stress redistribution in optical microscopy and optical which the focal thinning results coherence elastography. All hold in increased biomechanical stress, promise to aid in the development leading to deformation and a fur- of patient-specifi c corneal cross- ther increase in stress, driving dis- linking procedures through im- Fig. 2. Slit lamp photograph ease progression.11 If such theories proved understanding of regional illustrating ribofl avin in the corneal are borne out by future research, differences in corneal stiffness. stroma following the loading phase.

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020_RCCL0516_F3_CXL-Update.indd 21 4/25/16 2:02 PM CORNEAL CROSSLINKING: RESHAPING KERATOCONUS MANAGEMENT

en the amount of time necessary to deliver the equivalent total energy dose (Figure 3). Clinical studies evaluating the effi cacy of acceler- ated CXL demonstrate stability or

fl attening of Kmax comparable to results achieved with the Dresden protocol.27,28 However, some inves- tigators have examined the stromal demarcation lines following accelerated CXL—interpreted as an indirect indicator of the relative CXL treatment depth, commonly observed in the fi rst one to three months post-op—and reported a trend towards shallower depth of the line following accelerated vs. conventional techniques.27,29-32 This difference in the demarca- Fig. 3. The laser crosshairs of the KXL crosslinking system (Avedro) tion line depth may be modulated positioned to align the optical head of the system with the patient’s eye. by oxygen bioavailability within the stroma. Oxygen levels in the Though further investigation is intra- and postoperative comfort, cornea are depleted by the photo- still necessary, signifi cant advance- and improve effi cacy, which could chemical reactions of CXL, with ments have been made in the last result in more meaningful corneal rapid oxygen replenishment once decade in regards to understanding reshaping in addition to disease the UVA source is removed.33 the photochemical mechanisms stabilization. One method to increase oxygen that result in the formation of new One such modifi cation is the concentration in the cornea during crosslinks in the cornea. Under the introduction of transepithelial accelerated CXL is to program right conditions, the interaction crosslinking, which is intended the UVA emission to turn on and of UVA and ribofl avin sets off a to improve patient comfort and off at repeated time intervals to complex chain of photochemical minimize infection risk.20 While allow for diffusion of oxygen into reactions, resulting in the forma- standard formulations containing the stroma during pauses in UV tion of covalent bonds within the 0.1% ribofl avin and 20% dextran exposure.34 Hence, pulsed irra- intracellular matrix of the collagen show minimal penetration through diation may have the potential lamellae, which effectively stiffens an intact epithelium, new ribo- to increase the corneal stiffening the cornea in the treated zone.5 fl avin formulations with added effect obtained with the same UVA This increase in stiffness may corneal-enhancing compounds like dose, and may potentially lead to a break the cycle of biomechanical BAC and/or EDTA, can improve reduction in procedure time by in- weakening that results in ectasia, ribofl avin diffusion despite epi- creasing the treatment effi ciency of further limiting progression of the thelial presence.21-23 Attempts to high irradiance CXL. Preliminary disease.11 disrupt the epithelial tight junc- results with pulsed irradiation With an improved understand- tions without debriding the epi- are promising, indicating safety ing of corneal biomechanical thelium have also been carried out equivalent to the continuous UV behavior and the mechanisms of using disruptive devices, surgical exposure protocols, albeit with CXL comes a wave of new clinical sponges or iontophoretic delivery greater demarcation line depth.35,36 efforts aimed at optimizing the through the use of a mild electrical However, longer follow-up is procedure’s treatment parameters. current.24-26 necessary to determine whether Namely, this ongoing research Another procedural modifi ca- demarcation line depth signifi cant- will focus on deriving new CXL tion is the use of accelerated CXL, ly impacts clinical outcomes. delivery protocols to decrease which uses higher irradiance UVA Interestingly, this correlation treatment time, increase both (7mW/cm2 to 45mW/cm2) to short- between the depth of the de-

22 REVIEW OF CORNEA & CONTACT LENSES | MAY 2016

020_RCCL0516_F3_CXL-Update.indd 22 4/25/16 2:02 PM corneal crosslinking (PiXL) is the clinical product of this theoretical approach. PiXL uses a topographically customized UVA pattern to induce a variable distribution of cross- linking in the stroma (Figure 5). The CXL treatment depth (Z-axis) is controlled by the UVA energy Fig 4. A case example of topographic fl attening after corneal crosslinking. Preoperative axial topography is shown at left, three-month postoperative parameters, while the lateral aspect topography at center, and a diff erence map revealing the change between the (X-axis and Y-axis) is controlled two time points is shown at right. by the specifi c UVA pattern ap- plied using a crosslinking system marcation line and the different patterns that would allow sur- containing a digital micromirror CXL protocols applied suggests a geons to focally stiffen the weakest device (a semiconductor comprised possible opportunity to customize region of the cornea rather than of adjustable microscopic mirrors CXL treatment parameters to tar- the conventional approach of uni- that can create a desired beam pro- get a specifi c depth—for example, formly stiffening the entire central fi le).38 The fi rst clinical case report to accomplish a shallower CXL cornea.12 Three-dimensional mod- of PiXL application in a kerato- effect in cases of thinner corneas eling of this concept suggests a po- conus patient used the KXL II by varying irradiance, total dose or tential for greater normalization of System (Avedro) and demonstrated pulse interval.37 the cornea (inferior fl attening and improvement in uncorrected visual superior steepening), presenting acuity from 20/40 to 20/25 and CUSTOMIZED CROSSLINKING the opportunity to combine visual reduction in corneal astigmatism TO RESHAPE THE CORNEA rehabilitation and biomechanical of 0.8D at six months post-op.39 Though corneal fl attening and stabilization into a single proce- Though PiXL is not yet available visual improvement have been dure. Photorefractive intrastromal in the United States, a number reported, the primary goal of con- ventional CXL protocols is in fact to stabilize the cornea against pro- gression and prevent further visual loss (Figure 4). Conventional CXL achieves this effect by uniformly stiffening the central 9mm of the anterior stroma. With the new understanding of the distribution of biomechanical forces within the keratoconic cornea comes the potential to customize crosslinking treatment plans based on an indi- vidual patient’s characteristics and corneal topography to achieve not just stabilization but also improve- ment in corneal shape. In addition to varying the depth of crosslinking by modifying pa- rameters like UVA irradiance, total energy dose and/or pulse interval, the lateral distribution of crosslink formation in the cornea may be better controlled through the use Fig. 5. Customized, dual-arc UVA treatment pattern applied to the central of customized UVA illumination cornea of a patient with intracorneal ring segments, using the KXL II system.

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020_RCCL0516_F3_CXL-Update.indd 23 4/25/16 2:02 PM CORNEAL CROSSLINKING: RESHAPING KERATOCONUS MANAGEMENT

Clin Exp Optom. 2013;17(Figure 2):1-10. 24. Rechichi M, Mazzotta C, Daya S, et al. Epithelial of ongoing studies in Europe are 4. Ashwin PT, McDonnell PJ. Collagen cross-link- disruption pulsed accelerated cross-linking : one evaluating its potential. Several age: a comprehensive review and directions for year results. In: 10th CXL Congress 2014 Zurich; future research. Br J Ophthalmol. 2009. 2014. groups presented preliminary 5. Meek KM, Hayes S. Corneal cross-linking - a 25. Stojanovic A, Chen X, Jin N, et al. Safety review. Ophthalmic Physiol Opt. 2013;33(2):78-93. and effi cacy of epithelium-on corneal collagen results at the 11th International cross-linking using a multifactorial approach to Congress of Corneal Cross-linking 6. Raiskup F, Spoerl E. Corneal crosslinking with achieve proper stromal ribofl avin saturation. J ribofl avin and ultraviolet A. I. Principles. Ocul Surf. Ophthalmol. 2012;2012:498435. 2013;11(2):65-74. in December 2015. Mazzotta used 26. Cassagne M, Laurent C, Rodrigues M, et al. confocal microscopy to demon- 7. Gomes JAP, Tan D, Rapuano CJ, et al. Global Iontophoresis transcorneal delivery technique for Consensus on Keratoconus and Ectatic Diseases. transepithelial corneal collagen crosslinking with strate the spatial distribution of the Cornea. 2015;34(4):359-369. ribofl avin in a rabbit model. Invest Ophthalmol Vis crosslinking treatment effect in re- 8. Lewis PN, Pinali C, Young RD, et al. Structural Sci. 2014;33(0):1-6. interactions between collagen and proteo- 27. Tomita M, Mita M, Huseynova T. Accelerated sponse to various treatment proto- glycans are elucidated by three-dimensional versus conventional corneal collagen crosslinking. cols, while Cassange and Behndig electron tomography of bovine cornea. Structure. J Cataract Refract Surg. 2014;40(6):1013-1020. 2010;18(2):239-245. 28. Mita M, Waring GO, Tomita M. High-irradiance presented the preliminary results 9. Meek KM, Tuft SJ, Huang Y, et al. Chang- accelerated collagen crosslinking for the treat- es in collagen orientation and distribution in ment of keratoconus: Six-month results. J Cataract of two prospective evaluations of keratoconus corneas. Invest Ophthalmol Vis Sci. Refract Surg. 2014;40(6):1032-1040. PiXL compared to conventional 2005;46(6):1948-1956. 29. Seiler T, Hafezi F. Corneal cross-linking-in- 10. Meek KM, Boote C. The use of X-ray scattering duced stromal demarcation line. Cornea. CXL that demonstrated statisti- techniques to quantify the orientation and dis- 2006;25(9):1057-1059. cally signifi cant improvement in tribution of collagen in the corneal stroma. Prog 30. Mazzotta C, Caporossi T, Denaro R, et al. Mor- Retin Eye Res. 2009;28(5):369-392. phological and functional correlations in ribofl avin keratometric parameters and vi- 11. Roberts CJ, Dupps WJ. Biomechanics of corneal UV A corneal collagen cross-linking for keratoco- sual acuity with PiXL.40-42 Further ectasia and biomechanical treatments. J Cataract nus. Acta Ophthalmol. April 2010:1-7. Refract Surg. 2014;40(6):991-998. 31. Touboul D, Efron N, Smadja D, et al. Corneal evaluations and longer follow-up 12. Roy AS, Dupps WJ. Patient-specifi c computa- Confocal Microscopy Following Conventional, will be needed to determine the tional modeling of keratoconus progression and Transepithelial, and Accelerated Corneal Collagen diff erential responses to collagen cross-linking. Cross-linking Procedures for Keratoconus. J Re- optimum parameters for custom- Invest Ophthalmol Vis Sci. 2011;52(12):9174-9187. fract Surg. 2012;28(11):769-776. ized corneal crosslinking using the 13. Scarcelli G, Besner S, Pineda R, Yun SH. Biome- 32. Kymionis G, Tsoulnaras K. Corneal Stromal chanical characterization of keratoconus corneas Demarcation Line Determined With Anterior Seg- PiXL technique, however. ex vivo with brillouin microscopy. Invest Ophthal- ment Optical Coherence Tomography Following mol Vis Sci. 2014;55(7):4490-4495. a Very High Intensity Corneal Collagen Cross-. 14. Girard MJA, Dupps WJ, Baskaran M, et al. Cornea. 2015:664-667. XL has revolutionized ker- Translating Ocular Biomechanics into Clinical 33. Kamaev P, Friedman MD, Sherr E, Muller D. Practice: Current State and Future Prospects. Photochemical kinetics of corneal cross-link- Catoconus management by Current eye research. 2015;40(1):1-18. ing with ribofl avin. Invest Ophthalmol Vis Sci. targeting underlying corneal insta- 15. Wollensak G, Spoerl E, Seiler T. Ribofl avin/ 2012;53(4):2360-2367. doi:10.1167/iovs.11-9385. ultraviolet-a–induced collagen crosslinking for 34. Kamaev P, Eddington W, Rood-Ojalvo S, et bility and successfully stopping or the treatment of keratoconus. Am J Ophthalmol. al. Accelerated corneal cross-linking with pulsed 2003;135(5):620-627. light. Invest Ophthalmol Vis Sci. 2013;54(E-Ab- slowing down disease progression. stract 5288). 16. Wittig-Silva C, Chan E, Islam FM et al. A This innovation has energized re- randomized, controlled trial of corneal collagen 35. Mazzotta C, Traversi C, Caragiuli S, Rechichi search efforts to better understand cross-linking in progressive keratoconus: three- M. Pulsed vs continuous light accelerated corneal year results. Ophthalmology. 2014;121(4):812-821. collagen crosslinking: in vivo qualitative investiga- the mechanisms driving kerato- tion by confocal microscopy and corneal OCT. Eye 17. O’Brart DPS, Kwong TQ, Patel P, et al. Long- (Lond). 2014;28(10):1179-1183. conus progression and to develop term follow-up of ribofl avin/ultraviolet A (370 nm) corneal collagen cross-linking to halt the 36. Mazzotta C, Traversi C, Paradiso AL, et al. new diagnostic instrumentations to progression of keratoconus. Br J Ophthalmol. Pulsed Light Accelerated Crosslinking vs Contin- February 2013. uous Light Accelerated Crosslinking: One-Year allow for earlier diagnosis. In ad- Results. J Ophthalmol. 2014:1-15. 18. Chang CY, Hersh PS. Corneal collagen dition, the next generation of CXL cross-linking: a review of 1-year outcomes. Eye 37. Friedman MF, Smirnov M, Kamaev P, Mrochen Contact Lens. 2014;40(6):345-352. M, Lytle G, Muller D. Can we safely cross-link protocols is expected to attempt thinner corneas: Pathways for optimized CXL 19. Raiskup F, Theuring A, Pillunat LE, Spoerl E. treatment planning. European Society of Cataract to further normalize the irregular Corneal collagen crosslinking with ribofl avin and & Refractive Surgery Annual Meeting, Barcelona, ultraviolet-A light in progressive keratoconus: Ten- Spain, September 3, 2015. Poster.) contour of treated corneas and year results. J Cataract Refract Surg. 2015;41(1):41- 46. 38. Lytle G. Advances in the Technology of Cor- potentially improve patients’ visual neal Cross-Linking for Keratoconus. Eye Contact 20. Koppen C, Wouters K, Mathysen D, Rozema RCCL Lens. 2014;0(0):1-7. function. J, Tassignon M-J. Refractive and topographic The author thanks Grace Lytle, results of benzalkonium chloride-assisted tran- 39. Kanellopoulos AJ, Dupps WJ, Seven I, Asimel- sepithelial crosslinking. J Cataract Refract Surg. lis G. Toric topographically customized transep- OD, for her contributions to this 2012;38(6):1000-1005. ithelial, pulsed, very high-fl uence, higher energy and higher ribofl avin concentration collagen article. Dr. Lytle is employed by 21. Hayes S, O’Brart DP, Lamdin LS, et al. Eff ect of complete epithelial debridement before ribo- cross-linking in keratoconus. Case Rep Ophthal- Avedro, the manufacturer of the fl avin-ultraviolet-A corneal collagen crosslinking mol. 2014;5(2):172-180. KXL crosslinking system. therapy. J Cataract Refract Surg. 2008;34(4):657- 40. Mazzota C. Biological reations after CXL.Paper 661. doi:10.1016/j.jcrs.2008.02.002. Presented at: 11th International Congress of Cor- 22. Baiocchi S, Mazzotta C, Cerretani D, Caporossi neal Cross-Linking; 2015 Dec 4-5; Boston, MA. 1. Rebenitsch RL, Kymes SM, Walline JJ, Gordon T, Caporossi A. Corneal crosslinking: ribofl avin 41. Behndig A. Clinical results with PiXL in kerato- MO. The lifetime economic burden of keratoconus: concentration in corneal stroma exposed with conus Eyes. Paper Presented at: 11th International a decision analysis using a markov model. Am J and without epithelium. J Cataract Refract Surg. Congress of Corneal Cross-Linking; 2015 Dec 4-5; Ophthalmol. 2011;151(5):768-773.e2. 2009;35(5):893-899. Boston, MA. 2. Rabinowitz YS. Keratoconus. Surv Ophthalmol. 23. Raiskup F, Pinelli R, Spoerl E. Ribofl avin 42. Cassagne M. Clinical results with PiXL in 1998;42(4):297-319. Osmolar Modifi cation for Transepithelial Corneal keratoconus Eyes. Paper Presented at: 11th Inter- 3. Chan E, Snibson GR. Current status of corneal Cross-Linking. 2012;37(September 2010):234-238. national Congress of Conreal Cross-Linking; 2015 collagen cross-linking for keratoconus: a review. doi:10.3109/02713683.2011.637656. Dec 4-5; Boston, MA.

24 REVIEW OF CORNEA & CONTACT LENSES | MAY 2016

020_RCCL0516_F3_CXL-Update.indd 24 4/25/16 2:02 PM Up to 18 CE Credits BERMUDA (COPE approval pending)

ies a log nd o T r Image courtesy of Hamilton Princess & Beach Club, A Fairmont Managed Hotel n e h a c t

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2016_Bermuda_spread.indd 1 3/24/16 10:56 AM Surgical Management of Keratoconus: BATTLEof the BULGE

he structural instability fi bers of the cornea by increasing demonstrated improvements in brought on by corneal the collagen crosslinks. Evidence corrected distance visual acuity ectasia and thinning for its effi cacy and safety contin- (CDVA) and spherical equivalent makes keratoconus ues to be reviewed.4,5 Available and a reduction of topometric Tnotoriously diffi cult to globally since the late 1990s, the astigmatism over the fi rst few years manage long-term, as the cornea procedure has just received FDA in 60% of patients. Note, there becomes—literally—a moving clearance for use in the US. does exist a possibility for clinical target. Visual fl uctuations and Rx Other surgical interventions regression over the long term, as changes in response to corneal should be considered when corneal this treatment modality does noth- shape change are common. irregularity is so great that spec- ing to blunt the progression of the Treatments for keratoconus have tacle or contact lens wear is no disease, based on patients followed signifi cantly advanced and diver- longer tolerated, when central over fi ve years.7 Currently, ongoing sifi ed since the disease was fi rst scarring is limiting vision, or when studies are evaluating the potential called to attention by Burchard signifi cant corneal thinning may benefi t of combining ICRS with Mauchart in 1748.1 First-line preface a possibility of traumatic corneal crosslinking as ultimate- solutions include spectacles and perforation (a rare but devastating ly—even after ICRS implanta- contact lenses, with one caveat: potential consequence of steroid tion—the patient’s disease may soft lenses may be adequate to cor- use). Other FDA-approved surgi- continue to progress and eventual- rect both myopic and astigmatic cal options include intrastromal ly require corneal transplantation.8 errors early in the disease process, corneal ring segments (ICRS) and but rigid gas permeable lenses corneal transplantation. ABOUT THE AUTHORS will often become necessary as it ICRS are minimally invasive Dr. Behshad is a clinical progresses and corneal irregularity plastic polymer arc-shaped seg- instructor at the Gavin increases. Newer customizable ments inserted into the cornea of Herbert Eye Institute at UC Irvine California. His lenses—such as sclerals, Rose K or keratoconus patients with mild research interests include Boston lenses—offer higher oxygen cases of irregular astigmatism the use of the femtosecond laser for corneal surgery as a permeability and better comfort and preserved corneal thickness. method to improve endothelial for these patients.2,3 However, in Successful implantation requires transplantation techniques. some cases, simple vision correc- a 6mm diameter zone of central Dr. Vu is a fourth-year medical student at the UC Irvine tion methods may not always be cornea that measures more than School of Medicine. She adequate. What other choices do 450µm in thickness. The ring matched into UC Irvine’s Ophthalmology Residency patients have then? segments are inserted into a pocket Program and is looking that can either be made manually forward to diagnosing, treating and managing CURTAILING PROGRESSION or with a femtosecond laser. The ophthalmic diseases. Ultraviolet A ribofl avin-mediat- incision is made based on the steep Dr. Farid is director of the cornea, ed corneal collagen crosslinking axis, as determined by corneal cataract and refractive surgery department and vice-chair (CXL) may help prevent kera- topography. of ophthalmic faculty at the toconic disease progression in The goal of ICRS is to reduce Gavin Herbert Eye Institute at UC Irvine, where she also patients who exhibit a clear central corneal steepening as well as serves on the residency cornea and minimum corneal irregular astigmatism, so that education committee and is director of the cornea thickness of 400µm. This surgical patients can use contact lenses or fellowship program. She also technique involves the biomechan- spectacles with improved toler- serves as an associate medical director for Sight Life Eye Bank. ical strengthening of the collagen ability.6 Long-term research has

26 REVIEW OF CORNEA & CONTACT LENSES | MAY 2016

026_RCCL0516_F4_KCN-Surgical-Management.indd 26 4/25/16 2:01 PM Corrective lenses can serve patients well for years, but a lasting solution may require a trip to the OR. By Soroosh Behshad, MD, Priscilla Q. Vu, and Marjan Farid, MD

ADVANCED STAGE OPTIONS The advent of the femtosecond Top-Hat Patients with more pronounced laser has allowed for greater preci- presentations of keratoconus who sion of wound architecture in both are unable to tolerate contact lens- the host and donor tissue, allowing es, who have signifi cant scarring for quicker healing of the incision, on the central visual axis or who improved approximation of tissue Mushroom fail to improve in visual acuity and quicker visual recovery with with corneal crosslinking or ICRS FLEK.10 During the procedure, the may require keratoplasty. femtosecond laser pushes micro- The choice of employing lamel- cavitation bubbles to a precise lar vs. full-thickness keratoplas- corneal depth through photodis- Zig-Zag ty will depend on the extent of ruption. These bubbles combine corneal scarring. Types of corneal in a manner that results in planar transplantation techniques include cuts of tissue, a technique that was conventional full-thickness pene- originally pioneered for use in laser Fig. 1. From top to bottom: schematic of “top-hat” incision; schematic of trating keratoplasty (PKP), deep in-situ keratomileusis (LASIK) fl ap “mushroom” incision; and schematic anterior lamellar keratoplasty creation.9 Various confi gurations of “zig-zag” incision. (DALK) and femtosecond-enabled for keratoplasty incisions have keratoplasty (FLEK), which can be been designed with the femtosec- Although no head-to-head performed as either a full-thickness ond laser, including but not limited comparisons have been conducted graft procedure or in combination to “top hat,” “mushroom” and between the various confi gurations with the DALK procedure (known “zig-zag” (Figure 1). of wound architecture, the zig-zag- as fs-DALK). Evidence has demonstrated these shaped incision appears to have In conventional full-thickness wound confi gurations allow more some advantage over the others, PKP, manual trephination can lead surface area for tissue healing— as it leaves room for a smoother to misalignment of host and donor thus decreasing rates of wound graft/host interface transition as tissue, which may ultimately heal leakage and enabling faster visual well as decreased vertical and in such a way as to limit visual recovery—lower levels of post- torsional misalignments due to its outcome.9 Patients most likely to operative astigmatism and earlier ability to create a hermetic wound benefi t from a conventional PKP removal of sutures (Figure 2).11-17 seal (Figure 3).10 rather than a FLEK operation in- clude those who possess a mechan- ical issue like a history of glauco- ma implant surgery with bleb, or anterior staphyloma that prevents the laser interface from having direct contact with the corneal limbus due to the irregular ocular surface. As such, contraindications to FLEK include a history of glau- coma fi ltering surgery, the presence Fig. 2. Left: A one-month postoperative slit lamp photo demonstrating a 24-bite running 10-0 nylon suture technique with zig-zag incision. Right: of an aqueous drainage device or High magnifi cation of graft/host interface with running suture demonstrating narrow palpebral fi ssures. smooth surface transition at one month following zig-zag incision.

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026_RCCL0516_F4_KCN-Surgical-Management.indd 27 4/25/16 2:01 PM SURGICAL MANAGEMENT OF KERATOCONUS: BATTLE OF THE BULGE

not good candidates for DALK; instead, full-thickness grafts are recommended in these cases. Additionally, extreme corneal thinning increases the risk for Descemet’s membrane perforation, requiring intraoperative conversion of fs-DALK to a full-thickness keratoplasty. Fortunately, doing so maintains the advantages of femto- 19 Fig. 3. OCT scan of a zig-zag incision taken one month post-op shows good second laser incision. alignment of donor and host tissue at both the anterior and posterior surfaces. here is a lack of reported data Regarding FLEK—an alternative Additionally, fs-DALK is easier Ton the best surgical option at to conventional PKP—some stud- to perform than manual DALK any given stage of keratoconus; as ies have demonstrated an improve- because surgeons have the ability such, ultimately, the clinician must ment in CDVA, spherical equiva- to customize the posterior ab- decide based on exam fi ndings, lent and topographic astigmatism. lation depth, allowing for more patient symptoms and disease state Additionally, the advanced preci- accurate dissection just anterior (Figure 5). As always, initial man- sion provided by the femtosecond to Descemet’s membrane and agement should fi rst involve spec- laser allows for adequate scarring reducing risk for perforation. Since tacles and/or contact lens wear. at four months post-op, creating a presentation of corneal hy- Corneal crosslinking may play a the opportunity for possible early drops can involve the Descemet’s role in stabilizing disease progres- suture removal and topical steroid membrane, keratoconus patients sion, but further research is needed tapering.8 with a history of hydrops are to determine effi cacy and safety. The deep anterior lamellar ICRS can decrease refractive error keratoplasty surgical approach to and irregular astigmatism. Corneal anterior corneal disease allows for transplantation is reserved for selective replacement of diseased A more advanced disease; however, corneal epithelium and stroma patient outcomes have been vastly after separation from healthy host improved by recent improvements Descemet’s membrane and endo- in technology and technique. The thelium. DALK is benefi cial for B advent of the femtosecond laser keratoconus in that it provides the has given surgeons a new tool for safety of extraocular surgery, the achieving better and faster visual elimination of endothelial rejec- recovery. Future options may also tion, the potential for shorter post- C include novel artifi cial or engi- op steroid regimens and increased neered corneas for keratoplasty. RCCL graft longevity.18 Of note, stromal 1. Rabinowitz YS. Keratoconus. Surv Ophthalmol rejection is still a risk and should D 1998;42:297-319. be routinely monitored for. 2. Rathi VM, Mandathara PS, Dumpati S. Indian J The DALK “big bubble” tech- Fig. 4. The fs-DALK graft technique. Ophthalmol. 2014 Aug;61(8):410-5. 3. Barnett M, Mannis MJ. Contact lenses in the nique, combined with the femto- (a) Baring of Descemet’s (highlighted management of Keratoconus. Cornea. 2011 second laser, was fi rst described in red) using “big bubble” technique Dec;30(12):1510-6. in 2009.19,20 Femtosecond DALK after standard non-penetrating 4. Hafezi F, Mrochen M, Iseli HP, Seiler T. Collagen femtosecond laser zig-zag incision. crosslinking with ultraviolet-A and hypoosmolar offers the advantages of FLEK, ribofl avin solution in thin corneas. J Cataract (b) “Big bubble” technique with Refract Surg. 2009;35:621–4. including better donor/host fi t, bubble dissecting tissue anterior to 5. Raiskup-Wolf F, Hoyer A, Spoerl E, Pillunat LE. increased surface area apposition Descemet’s membrane. Collagen crosslinking with ribofl avin and ultravio- let – A light in keratoconus: Long-term results. J and faster wound healing, as well (c) Removal of entire stroma, Cataract Refract Surg. 2008;34:796–801. as the inherent benefi ts of DALK preserving host DM and endothelium. 6. Torquetti L, Berbel RF, Ferrara P. Long-term follow-up of intrastromal corneal ring seg- in treating stromal and anterior (d) Suturing of donor tissue after donor ments in keratoconus. J Cataract Refract Surg corneal disease (Figure 4).21-23 endothelium has been removed. 2009;35:1768-73.

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0026_RCCL0516_F4_KCN-Surgical-Management.indd26_RCCL0516_F4_KCN-Surgical-Management.indd 2828 44/25/16/25/16 2:322:32 PMPM ies a log nd o T r n e h a c t

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IN VISION CARE MEETINGS 2016

REVIEW OF OPTOMETRY® EDUCATIONAL MEETINGS OF CLINICAL EXCELLENCE SAVE THESE DATES! 3 WAYS TO REGISTER www.reviewofoptometry.com/conferences Email Lois DiDomenico: [email protected] Call: 866-658-1772 REGISTER EARLY Program Chair: Paul Karpecki, OD

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Fig. 5. Surgical management of keratoconus decision tree.

7. Vega-Estraga, A Alio, JL Plaza-Puche AB. 16. Cheng YY, Tahzib NG, van Rij G, et al. Fem- Bermuda Keratoconus progression after intrastromal ring tosecond laser-assisted inverted mushroom The Fairmont segment implantation in you patients: Five-Year keratoplasty. Cornea. 2008; 27(6):679-85. Hamilton Princess follow-up. J Cataract Refract Surg 2015;41:1145- 17. Bahar I, Kaiserman I, Lange AP, et al. Femto- June 9 - 12, 2016 52. second laser versus manual dissection for top- 8. Shetty R, Kaweri L, Pahuja N, et al. Current hat penetrating keratoplasty. Br J Ophthalmol. review and a simplifi ed “fi ve-point management 2009; 93(1):73-8. algorithm” for keratoconus. Indian J Ophthalmol. 2015 Jan;63(1):46-53. 18. Reinhart WJ, Musch DC, Jacobs DS, et al. Deep anterior lamellar keratoplasty as an alterna- 9. Farid M, Steinert R, Garg S, Wade M, et al. Cor- tive to penetrating keratoplasty a report by the nea: Fundamentals, Diagnosis, and Management. american academy of ophthalmology. Ophthal- Vol 2. 4th ed. Philadelphia: Elsevier Mosby. mology. Jan 2011;118(1):209-18. Image courtesy of Hamilton Princess & Beach Club, A Fairmont Managed Hotel 10. Farid M, Steinert RF, Gaster RN, et al. Com- 19. Farid M, Steinert RF. Deep anterior lamellar parison of penetrating keratoplasty performed keratoplasty performed with the femtosecond with a femtosecond laser zig-zag incision versus laser zigzag incision for the treatment of stromal conventional blade trephination. Ophthalmology. 2009 Sept;116(9):1638-43. corneal pathology and ectatic disease. J Cata- ract Refract Surg. 2009;35:809-13. 11. Ignacio TS, Nguyen TB, Chuck RS, et al. Top- hat wound confi guration for penetrating kerato- 20. Price FW, Price MO, Grandin JC, et al. Deep plasty using the femtosecond laser: a laboratory anterior lamellar keratoplasty with femtosec- model. Cornea 2006 Apr; 25: 336-340. ond-laser zigzag incisions. J Cataract Refract Surg. 2009;35:804-8. 12. Steinert RF, Ignacio TS, Sarayba MA. Top-hat shaped penetrating keratoplasty using the 21. Lu Y, Shi YH, Yang LP, et al. Femtosecond femtosecond laser. Am J Ophthalmol 2007; laser-assisted deep anterior lamellar keratoplasty 143(4):689-91. for keratoconus and keratectasia. International journal of Ophthalmology. 2014;7(4):638-43. Philadelphia 13. Farid M, Kim M, Steinert RF. Results of Philadelphia Marriott 22. Buzzonetti L, Petrocelli G, Valente P. Fem- penetrating keratoplasty performed with a Downtown femtosecond laser zigzag incision: initial report. tosecond laser and big-bubble deep anterior Ophthalmology. 2007;114(12):2208-12. lamellar keratoplasty: a new chance. Ophthalmol- October 7 - 9, 2016 14. Buratto L, Bohm E. The use of the femto- ogy. 2012;2012:264590. second laser in penetrating keratoplasty. Am J 23. Shehadeh-Mashor R, Chan CC, Bahar I, et Ophthalmol. 2007;143(5):737-42. al. Comparison between femtosecond laser 15. Price FW, Price MO. Femtosecond laser mushroom confi guration and manual trephine Interactive shaped penetrating keratoplasty: one-year straight-edge confi guration deep anterior lamel- CE Workshops results utilizing a top-hat confi guration. Am J lar keratoplasty. British Journal of Ophthalmolo- Ophthalmol. 2008; 145(2):210-14. gy. Jan 2014;98(1):35-9. *Approval pending Administered by Review of Optometry® 16-19 CE Stock Images: * ©iStock.com/JobsonHealthcare Credits

026_RCCL0516_F4_KCN-Surgical-Management.indd 29 4/25/16 2:01 PM 1 CE Credit (COPE Approval Pending) What CORNEAL SHAPE About CORNEAL

ne of the most sensi- both the experienced and neophyte if a particular cornea is normal tive yet underused in- user when properly armed with an or abnormal, one of the simplest struments in practice understanding of the fundamentals. analyses possible is to assess the today for identifying This article will discuss the var- range of power distributed across Oand characterizing ious capabilities and functions of the corneal surface.5 Using an corneal disorders is the corneal the technology in disease screening, “axial” interpretation, determine topographer. This device provides particularly as it relates to keratoco- the fl attest dioptric power that us with an array of analysis options nus and corneal thinning disorders. the topographer can read on the that can accurately reveal condi- selected cornea. Then, fi nd the tions that warrant our attention or TYPES OF UNITS steepest reading on the surface. The treatment. However, as with most Though dozens of corneal mapping dioptric difference between the two advanced instrumentation available systems exist, all can be categorized is the scale range of power (Figure to practitioners today, understand- as either refl ection or projection 1). Normal corneas distribute less ing and keeping track of the wide units.1 Refl ection systems map than 10D of power from the fl attest range of options for interpreting the anterior surface of the cornea to steepest readings on the axial results can be overwhelming. For and provide noninvasive tear fi lm display. This analysis option may example, which analysis display is breakup and stability testing as be described by some units as the best at uncovering the earliest signs added features.1,2 Newer refl ec- power or sagittal display. of a given disease? How should we tive-based topographers are capable Another analysis option of differentiate one condition from of measuring beyond the cornea diagnostic value is the tangential another? Which functions of the to provide information on scleral display, which is known in some technology help to monitor patients shape and sagittal depth, which instruments as the instantaneous or if long-term changes are occurring? can be benefi cial when fi tting large true curvature map.1 This inter- The corneal topographer can diameter contact lenses.3,4 However, pretation is more sensitive to fi nite be a powerful tool in the hands of regardless of additional features, all refl ective-based systems are only ABOUT THE AUTHORS capable of measuring the anteri- Mr. Kojima is a research or surface and therefore cannot scientist and clinical describe the posterior cornea or its instructor at the Pacifi c University College of thickness. Optometry. He is also By comparison, projection-based the clinical research and development director for instruments measure both the ante- Precision Technology and a rior and posterior corneal surface.1 fellow of the American Academy of Optometry, the British Contact This also allows for pachymetry Lens Association, the Scleral Lens Association and the International Orthokeratology measurement of the cornea’s Academy. thickness. Projection topography Dr. Eiden is the president provides a more comprehensive and medical director of Fig. 1. Analyze the scale range picture of the cornea as a whole and North Suburban Vision of power distributed across the Consultants. He is also the corneal surface on the axial map. is generally favored by surgical sites president and cofounder Distributions of less than 10D of when considering LASIK candidacy. of the International Keratoconus Academy. power are typical of normal eyes. When attempting to determine

30 REVIEW OF CORNEA & CONTACT LENSES | MAY 2016

030_RCCL0516_F5_CE-Keratoconus-Topography.indd 30 4/25/16 2:00 PM By Randy Kojima and Reveals S. Barry Eiden, OD Mapping the irregular cornea reveals much about disease status and its amenability to treatment. HEALTH Here’s a review.

Fig. 2. From left to right: (a) displays central keratoconus, also known as “nipple cones,” present within or near to the pupil, while (b) demonstrates oval keratoconus, which is usually larger in size than central cones and typically presents inferior to the corneal apex. It is also the most common cone presentation. (C) globic keratoconus involves the largest surface area of the cornea compared with central or over cones, while (d) pellucid marginal degeneration presents as thinning nearer to the peripheral cornea and can appear as “kissing doves” or “butterfl y wings” on the axial map.

surface changes in the eye, which er to the limbus than keratoconus jective appearance of topography the axial display can miss due to typically does (Figure 2d).6 contours and instead provide results the smoothing effects inherent in its using a mathematical analysis of the formula. A tangential map clearly DISEASE INDEXING corneal shape. defi nes the size, shape and position Though corneal topography axial The fi rst and possibly most of the anomaly or diseased tissue. and tangential maps can be used relied-upon technique for assess- This may be helpful when char- to identify when the condition is ing possible signs of disease is acterizing the presentation of one moderate or severe, neither inter- the inferior-superior (I-S) value condition over another. pretation can provide a defi nitive (Figure 3).7 This is a comparison of To help us simply and effi ciently diagnosis when the disease is mild the average power of the inferior classify the various types, one study or in the early-onset stage. For this cornea against the average of the identifi ed the following criteria: nip- reason, a series of disease detection superior cornea: if one hemisphere ple cones measure less than 3mm in indices have been developed; these is signifi cantly different from the diameter and generally are located eliminate the need for operator ex- other, this is a strong indicator of an more central to the pupil, while perience in comprehending the sub- abnormal and possibly diseased eye. oval keratoconic presentations had diameters of 3.0mm to 5.5mm and Release Date: May 2016 tinuing education course is joint-sponsored are usually present inferior to the vi- Expiration Date: May 1, 2019 by the Pennsylvania College of Optometry. Disclosure Statement: Mr. Kojima is the 6 Goal Statement: This course discusses the sual axis (Figure 2a and 2b). Cones clinical research and development direc- types and use of corneal topographers for greater than 5.5mm are considered tor for Precision Technology Services keratoconus evaluation. as well as a shareholder in KATT Design globic and involve much more of Faculty/Editorial Board: Randy Kojima and Group and clinical advisor to Medmont the corneal surface, but present in a S. Barry Eiden, OD International. Dr. Eiden has consulting, Credit Statement: COPE approval for 1 hour research and/or financial interest in the fol- smaller percentage of cases (Figure lowing: Alcon, Alden Labs, Bausch + Lomb, of continuing education credit is pending for 2c).6 Lastly, pellucid and Terrien’s CooperVision, Oculus, Oasis, Optovue, this course. Check with your state licensing Special Eyes, SynergEyes, Visionary Optics, marginal degenerations are other board to see if this counts toward your CE Vistakon, EyeVis Eye & Vision Research forms of corneal thinning disorders requirements for relicensure. Institute and the International Keratoconus that are rare and involve tissue clos- Joint-Sponsorship Statement: This con- Academy of Eye Care Professionals.

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steepest curvature, or apex, can also provide insight when diagnosing disease.6 For example, a normal, healthy eye typically exhibits an axial or tangential topography, with the steepest curvature near the center and a gradual rate of fl atten- ing towards the periphery (Figure 5a). By comparison, a keratoconic patient typically exhibits an apex inferior of center, with a higher Fig. 3. The I-S value measures Fig. 4. The surface asymmetry rate of curvature change within a the average power of the inferior index (SAI) compares the oblique smaller surface area of the topogra- and superior hemispheres and meridians. When one radial is a determines the diff erential. I-S mirror of its opposing radial, the eye phy (Figure 5b). In central or nipple values of greater than 1.5D are is considered symmetric. Higher SAI keratoconus, the apex might present indicative of an abnormal eye. values indicate more asymmetry. central to the pupil, but regardless of the position of the apex, it’s com- Considering approximately 90% of of an irregular cornea: though a mon in diseased and irregular eyes the corneal thinning disorders pres- normal, healthy eye would have a to see radical power changes within ent in the inferior hemisphere, it’s smooth central cornea to allow for tighter distances as compared with logical for the inferior cornea to be high quality visual acuity, a diseased normal, healthy eyes. signifi cantly steeper than the superi- eye with radical surface power Another interpretation that or. As such, I-S values greater than changes within the pupil is more topography software allows is the 1.5D are indicative of a diseased or likely to degrade vision. SRI values elevation display. This map overlays abnormal eye. greater than 0.80 are considered a best-fi t spherical surface on the an- Another commonly employed dis- abnormal; suspect corneal disease terior surface and defi nes where the ease detection index is the surface in such eyes. Simply put, the higher tissue is above the surface (red) and asymmetry index (SAI), which the value, the more abnormal the below (in blue) in microns.8 This compares the principal oblique surface. The scale range, I-S, SAI can be helpful in determining how meridians for symmetry (Figure 4).7 and SRI would indicate a symmet- high the elevation changes in the eye For example, the curvature from rical or normal eye is closer to zero surface are. Projection topographers the apex along axis 45° is compared values while a more irregular or dis- have the added benefi t of also being to the opposing curvature from the eased eye would be a higher value. able to image both the posterior center along axis 225°. Then, the The position and size of the and anterior surfaces (Figure 6). same hemi-chord comparison is completed between axis 135° and 315°. A completely symmetric eye would have an SAI value of zero, but if the oblique meridians are sig- nifi cantly different from each other, this indicates an asymmetric surface instead. SAI values greater than 1.0D are indicative of a diseased or irregular eye. The last disease detection index typically employed is the surface regularity index (SRI), a cen- ter-weighted analysis that deter- Fig. 5. Left to right: (a) displays a normal cornea with a displaced apex, while (b) displays an oval keratoconus cornea with an inferior cone. Note mines the relative smoothness of the the gradual rate of fl attening from the steepest central curvature to fl atter cornea.7 High power distributions peripheral shape in the former, and the signifi cant change in contour or within the pupil may be indicative shape within an acute area compared with the normal cornea in the latter.

32 REVIEW OF CORNEA & CONTACT LENSES | MAY 2016

030_RCCL0516_F5_CE-Keratoconus-Topography.indd 32 4/25/16 2:00 PM Research has suggested that the steepening over posterior elevation analysis may the cone, this be more accurate in identifying the likely indicates earliest signs of thinning disorders, disease progres- where at times the anterior surface sion, though may not reveal irregularity.9,10 it can also Often, characterizing the differ- be the result ence between keratoconus, pellucid of contact (PMD) and Terrien’s marginal lens molding. degeneration (TMD) can be diffi - Conversely, we cult. Corneal topography can help may often see to make distinguishing between more blue over the conditions relatively easier. For the cone on example, keratoconus appears on the subtractive the axial or tangential map (in red) map follow- as a round or oval acute area of ing corneal steep curvature, generally within crosslinking. the central or paracentral cornea.11 By comparison, PMD or TMD CONTACT present with red curvature more LENS Fig. 6. A typical projection topographer screen displaying anterior surface shape, anterior surface peripheral and closer to the lim- FITTING elevation, posterior surface elevation and corneal bus.12 Additionally, PMD takes on a Ultimately, if thickness (pachymetry). “kissing doves” or “butterfl y wing” we are diag- appearance on the axial map, while nosing corneal thinning disorders est point of elevation in microns TMD presents in various other pat- in our patients, there is a high (red area) and the lowest point of terns. Both PMD and TMD, how- likelihood we will be fi tting spe- depression (blue area) on each eye ever, are more typically associated cialty contact lenses to improve in a topographical elevation map. with lower fl at K (Kf) readings than the patient’s visual quality of life. The difference in height between keratoconus is. Using PMD as an Though many time-tested custom the two was considered to be the example, the Kf value is usually less soft lens options exist for keratoco- elevation differential (Figure 8). than or equal to 40D, whereas in nus today, the axial map can help The study determined that patients keratoconus the Kf value is usually us better understand the power of with less than or equal to 350µm greater than or equal to 45D. the anterior surface and whether of elevation change could achieve a When monitoring corneal disease a soft lens is the right choice for a successful corneal GP lens fi t 88% cases, the subtractive or difference particular patient. For example, if of the time, while those with greater maps can be helpful in defi ning the distributed power within the than 350µm of elevation change the smallest changes over time. pupil shows a range greater than required a scleral lens to fi t over the Typically, this analysis function is 10D, this could result in too much high asymmetry of the eye.13 used mostly in orthokeratology aberration for a custom soft lens In addition to steering us toward cases to assess the corneal chang- to mask. Additionally, the presence the right modality, corneal topog- es produced following overnight or absence of symmetry within raphers also come with contact lens wear. However, the subtractive the pupil can be telling: the more fi tting modules. These programs map—when employed in a diseased extreme the power distribution, the allow for simulated fl uorescein eye—can determine if the condition less likely a conventional or custom modeling of specifi c lens designs is stable or advancing. Comparing soft lens will be able to mask the to accurately determine the initial two scans, a subtractive map asymmetry. trial or custom parameters that are demonstrating all green indicates Another question we face is best suited to the eye (Figure 9). no changes over time, but red and whether to fi t a particular eye with Research demonstrates that corneal blue areas on the same map indicate a corneal GP or scleral lens. One topography fi tting software can steepening and fl attening, respec- study attempted to answer this predict the fl uorescein pattern 74% tively (Figures 7a and 7b). If there is question by identifying the high- of the time, regardless of the map

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Fig. 7. Left to right: (a) using the subtractive map, consecutive visits can be compared to determine if there is disease progression. The subtractive analysis on the right shows virtually all green, indicating little if any change in the corneal shape between visits. (b) The subtractive analysis on the right shows a signifi cant steepening (in red) between the two visits, indicating disease progression or contact lens molding that can also cause shape change.

quality.14 However, with good qual- tion of the surface characteristics (Zeimer) to measure the anterior ity images—which can be depen- of a structure. Corneal topography and posterior corneal surface, as dent on the eye’s surface and fi ssure is typically performed with Placido well as other anterior segment size—this fi tting accuracy can be ring technology that provides curva- structures. A rotating Scheimpfl ug improved to 95%. These modules ture data of the anterior corneal camera (single in Pentacam; dual can help reduce chair time and lab surface. In contrast, tomography is cameras in Galilei) creates a 360° costs by improving the effi ciency of the process of generating a two-di- representation of the anterior the trial process and accuracy of the mensional cross-sectional image of segment. initial custom parameters. a slice through a three-dimensional Scheimpfl ug tomography of the object. One method to achieve this anterior segment provides true TOMOGRAPHY VS. is through the use of Scheimpfl ug elevation-based data that allows for TOPOGRAPHY imaging (Figure 10). This tech- measurements of anterior corneal The term topography refers to a nology is used by instruments like elevation, posterior corneal eleva- detailed representation or descrip- Pentacam (Oculus) and Galilei tion, full corneal thickness (global pachymetry) and high quality imag- ing and structural measurements of the anterior segment. Elevation data can also be used to derive corneal curvature measurements analogous to the curvature data obtained by Placido-based corneal topography. True elevation corneal measure- ments and data of both the anterior and posterior cornea, along with global pachymetry data, allows for highly accurate detection of corneal Fig. 8. Using the elevation map, fi nd ectatic diseases like keratoconus. the highest point of curvature in Specifi cally, posterior corneal ele- microns in the red area. Then vation anomalies will precede and fi nd the opposing lowest point of Fig. 9. The contact lens modules in elevation in the blue area. When the some corneal topographers create be more advanced than anterior elevation diff erential is less than simulated fl uorescein patterns and corneal elevation and curvature 350µm, corneal GPs are frequently can be helpful tools in selecting anomalies in keratoconus. the fi rst diagnostic lens to try, or successful. When the diff erential There are many cases in which is greater than 350µm, consider a determining whether a specifi c lens scleral lens. might achieve a desired fi t. the anterior corneal surface is found

34 REVIEW OF CORNEA & CONTACT LENSES | MAY 2016

030_RCCL0516_F5_CE-Keratoconus-Topography.indd 34 4/25/16 2:00 PM to be normal—both in terms of ized by the thin point of the cornea hough we cannot rely on curvature and elevation—but a being below that normal range of Tjust one instrument, corneal posterior corneal elevation anom- minimum corneal thickness, it is the topography itself can be sensitive to aly still exists. This can result in rate of change of corneal thickness the earliest presentation of corneal what would be a false negative for from the thin point out peripherally thinning disorders, and can provide keratoconus detection, if only the that is the most sensitively diagnos- us with the ability to categorize anterior corneal surface were ana- tic, even in cases where the thick- the type of condition its severity. lyzed (such as with Placido-based ness of all points in the cornea are Understanding its functions can corneal topography). Conversely, statistically normal.17 greatly aid practitioners both in the some conditions or situations can Scheimpfl ug tomography can also characterization of the condition result in what would appear to aid in the differential diagnosis of and the selection of a contact lens suggest keratoconus, when, in true pellucid marginal corneal de- modality to best suit the patient. RCCL fact, the cornea is quite normal. generation. Traditionally, the classic 1. Mountford J, Ruston D, Dave T. Orthokeratology Displaced corneal apices and large “kissing dove” or “crab claw” pat- – Principles and Practice. New York: Butterworth deviations of the visual axis (large tern seen on curvature topography Heinemann; 2004:17-47. 2. Goto T, Zheng X, Klyce SD, et al. A new method angle Kappa) are two instances in maps is considered characteristic of for tear fi lm stability analysis using videokera- tography; Investigative Ophthalmology, Am J which Placido topography, or any PMD; however, because true PMD Ophthalmol. 2003 May; 135(5):607-12. representations of anterior corneal exhibits localized peripheral cor- 3. Eye surface profi ler (ESP), Eaglet Eye b.v., Lange surface curvature, would suggest neal thinning inferiorly 1mm from Schaft 7 G-II, 3991 AP Houten, The Netherlands. 4. Precision Ocular Metrology, USA. sMap 3D. keratoconus while elevation-based the limbus, in the majority of cases 5. Maeda N, Klyce SD, Smolek MK. Automated Scheimpfl ug would suggest an oth- the corneal thin point on global keratoconus screening with corneal topogra- phy analysis. Invest Ophthalmol Vis Sci. 1994 erwise normal cornea.16 pachymetry and corneal elevation May;35(6):2749-57. 6. McMahon T. Global Specialty Lens Symposium. Additionally, anomalies of global maps is actually signifi cantly more Las Vegas, Nev. January 2009. pachymetry are also highly diagnos- central in regular PMD than in true 7. Rabinowitz YS. Videokeratographic indices to aid in screening for keratoconus. J Refract Surg tic for keratoconus. Though many PMD. In fact, the global pachyme- 1995;11:371–379. cases of keratoconus are character- try maps and both the anterior and 8. Caroline P, Andre M. Elevating your knowledge of corneal topography. Contact Lens Spectrum. posterior corneal 2012 Feb. elevation maps are 9. Rabinowitz YS, Li X, Canedo AL, et al. OCT combined with videokeratography to diff erentiate quite typical of true mild keratoconus subtypes, J Refract Surg. 2014 keratoconus rather Feb;30(2):80-7. 18 10. Kollbaum P, Springs C. The psychometric prop- than pellucid. erties of Orbscan keratoconus detection indices. American Academy of Optometry Annual Meeting. One of the newest December 2006. developments in 11. Zadnik K, Barr JT, Edrington TB, et al. Baseline fi ndings in the collaborative longitudinal evalu- Scheimpfl ug tomog- ation of keratoconus (CLEK) study. 1998 Invest raphy is the tech- Ophthalmol Vis Sci. 1998 Dec;39(13):2537-46. 12. Wilson SE, Lin DTC, Klyce SD. Corneal topogra- nology’s ability to phy of keratoconus. Cornea 1991 Jan;10(1):2-8. image and measure 13. Zheng F, et al. Corneal Elevation Diff erences Fig. 10. Scheimpfl ug image of a case of advanced and the Initial Selection of Corneal and Scleral keratoconus along an oblique meridian. corneo-scleral pro- Contact Lens. Poster. Global Specialty Lens Sym- fi les. These measure- posium. Las Vegas, Nev. 2015. Photo: Oculus 14. Sindt SW, Grout TK, Kojima R. Evaluating Virtu- ments can be used to al Fitting for Keratoconus. Contact Lens Spectum. detect and quantify May 2011. 15. Tomidokoro A, Oshika T, Amano S, et al. Chang- asymmetries of es in anterior and posterior corneal curvatures in scleral shape when keratoconus. Ophthalmology. 2000;107: 1328–1332. 16. Dharwadkar S, BK Nayak. Corneal topography performed in 360°. and tomography. Jour of Clin Ophthalmol and Software is under de- Research. 2015;3(1):45-62. 17. Villavicencio OF, Gilani F, Henriquez MA, et al. velopment to enable Independent population validation of the belin/ ambrósio enhanced ectasia display: implications this data to be used for keratoconus studies and screening. Interna- in the virtual design tional Journal of Keratoconus and Ectatic Corneal Diseases, 2014 Jan-Apr;3(1):1-8. of both corneal and 18. Belin MW, Asota IM, Ambrosio R, Khachikian SS. What’s in a name: keratoconus, pellucid marginal scleral contact lenses degeneration and related thinning disorders. Oph- Fig. 11. Pentacam corneo-scleral profi le software. (Figure 11). thalmology. 2011 Aug;152(2):157-161.

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030_RCCL0516_F5_CE-Keratoconus-Topography.indd 35 4/25/16 2:00 PM WHAT CORNEAL SHAPE REVEALS ABOUT CORNEAL HEALTH

CE TEST ~ MAY 2016 EXAMINATION ANSWER SHEET

1. Reflection-based topography systems: What Corneal Shape Reveals About Corneal Health a. Map the anterior surface of the cornea and, in some cases, provide non- Valid for credit through May 1, 2019 invasive tear film break-up and stability testing. Online: This exam can also be taken online at www.reviewofcontactlenses.com. b. Measure both the anterior and posterior corneal surface to allow for Upon passing the exam, you can view your results immediately. You can also pachymetry measurement of the cornea’s thickness. view your test history at any time from the website. c. Can definitively determine whether the disease is mild or in the early-onset stage. Directions: Select one answer for each question in the exam and completely d. Are favored by surgical sites when considering patients for LASIK. darken the appropriate circle. A minimum score of 70% is required to earn credit. Mail to: Jobson Optometric CE, Canal Street Station, PO Box 488 New York, NY 10013 2. The inferior-superior value: a. Compares the principal oblique meridians for symmetry. Payment: Remit $20 with this exam. Make check payable to Jobson Medical b. Determines the relative smoothness of the cornea. Information LLC. c. Is a comparison of the average power of the inferior cornea against the Credit: COPE approval for 1 hour of CE credit is pending for this course. average of the superior cornea. d. Denotes a more abnormal corneal surface if higher in value. Sponsorship: Joint-sponsored by the Pennsylvania College of Optometry Processing: There is an eight-to-10 week processing time for this exam. 3. Keratoconic patients typically exhibit which of the following? a. Peripheral curvature closer to the limbus and a kissing doves appearance Answers to CE exam: on the axial map. 1. A B C D 6. A B C D b. Flattening over the peripheral cornea area of thinning and steepening 2. A B C D 7. A B C D opposite to the mid-point of thinning, resulting in against-the-rule or oblique astigmatism. 3. A B C D 8. A B C D c. Axial or tangential topography with the steepest curvature near the center 4. A B C D 9. A B C D and a gradual rate of flattening toward the periphery. 5. A B C D 10. A B C D d. An apex inferior of the center with a higher rate of curvature change within a smaller surface area of the topography. Evaluation questions (1 = Excellent, 2 = Very Good, 3 = Good, 4 = Fair, 5 = Poor) Rate the effectiveness of how well the activity: 4. When monitoring corneal disease, which topography map demonstrates if 11. Met the goal statement: 1 2 3 4 5 the condition is stable or advancing? a. Difference map. 12. Related to your practice needs: 1 2 3 4 5 b. Subtractive map. 13. Will help improve patient care: 1 2 3 4 5 c. Axial map. 14. Avoided commercial bias/influence: 1 2 3 4 5 d. Tangential map. 15. How do you rate the overall quality of the material? 1 2 3 4 5 5. The elevation display defines where the tissue is above and below the 16. Your knowledge of the subject increased: Greatly Somewhat Little surface in what colors, respectively? 17. The difficulty of the course was: Complex Appropriate Basic a. Red and green. b. Red and blue. 18. How long did it take to complete this course? ______c. Red and purple. d. Green and red. 19. Comments on this course: ______6. Which of the following conditions is Scheimpflug tomography best suited to identify? 20. Suggested topics for future CE articles: ______a. Keratoconus. b. Terrien’s marginal degeneration. ______c. Pellucid marginal degeneration. d. Keratoglobus. Identifying information (please print clearly):

7. What is the measurement criteria for distinguishing between the cones of First Name nipple, oval and globic keratoconus? a. Less than 4mm/4mm to 5mm/greater than 5mm. Last Name b. Less than 2mm/2mm to 6mm/greater than 6mm. c. Less than 5mm/5mm to 5.5mm/greater than 5.5mm. Email d. Less than 3mm/3mm to 5.5mm/greater than 5.5mm. The following is your: Home Address Business Address

8. SRI values greater than what are considered abnormal? Business Name a. 0.60. b. 0.70. Address c. 0.80. d. 0.90. City State

9. One of the newest developments in Scheimpflug tomography is its ability ZIP to: a. Create simulated fluorescein patterns. Telephone # - - b. Image and measure corneo-scleral profiles. c. Use displaced corneal apices and large deviations of the visual axis to Fax # - - identify keratoconus. d. Track corneal disease progression. By submitting this answer sheet, I certify that I have read the lesson in its entirety and completed the self-assessment exam personally based on the material present- 10. Approximately what percentage of corneal thinning disorders present in ed. I have not obtained the answers to this exam by fraudulent or improper means. the inferior hemisphere? a. 10%. b. 50% Signature: ______Date: ______c. 70%. d. 90% Please retain a copy for your records. LESSON 112914, RO-RCCL-0516

36 REVIEW OF CORNEA & CONTACT LENSES | MAY 2016

030_RCCL0516_F5_CE-Keratoconus-Topography.indd 36 4/25/16 2:00 PM Practice Progress By Mile Brujic, OD, and Jason Miller, OD, MBA

Boost Your Contact Lens Fits With Help from Your Staff A group eff ort can mean a stronger, more informed choice.

he typical contact lens smoothing the patient exam pro- exams, also check which diagnostic business may be missing cess enough to allow for an extra lenses you have on hand and order a substantial oppor- exam or two. the missing ones. tunity to grow if its 3. Spread the knowledge. Make Tstaff members are not THE HISTORY sure that multiple staff members adequately informed of the value Start by making an effort to have the capacity to help with that contact lens wearers bring to understand how the patient uses contact lens insertion and removal. an eye care practice. Totaled up their eyes throughout the day. This ensures someone is always over their lifetime, this population Proper questioning should include there to jump in and help with this represents a considerable source asking how many hours per day sometimes time-consuming process. of potential revenue.1 As such, it they spend on a digital device, as is important for practitioners to technology is now an integral part TIPS FOR TRAINING consider how they currently in- of our daily life. Next determine First and foremost, all staff mem- corporate contact lenses into their the number of hours each patient bers should know how to talk to repertoire and what steps should wears their contact lenses per day, patients about their contact lenses. be taken to continue moving including how many of those are This starts in the front offi ce with forward—whether it’s securing “comfortable” hours. Inquire spe- the answering of a patient’s phone new wearers or upgrading existing cifi cally about their “end of day” call. Have them mention contact ones. This strategic plan can’t be comfort. lenses at some point during this implemented by the doctor alone, Other small steps that may im- call: whether it’s to remind the pa- however. Instead, it all starts and prove effi ciency with contact lens tient to bring in their old prescrip- ends with the practice’s staff. wearers include: tion or to consider the possibility 1. Institute in-offi ce messaging. of trying lens wear, introduce them DELEGATION Whether to help with diagnostic to the concept of exploring contact Ensuring each patient receives lens fi tting or fi rst-time contact lenses during their next visit. enough attention from the doctor lens training courses, the ability to This conversation then continues during the overall encounter is communicate with staff members with the technician, so get them on key to a successful visit. As in any makes the adoption of any chang- board to discuss new opportunities business, adequate preparation es smoother and more effective. specifi c to the patient’s prescription and reliance on support from your For example, the use of signaling or introduce other lens possibilities staff can help make this happen. systems, texting or computer pro- to them. For example, if the pa- Though some practitioners may grams can help improve the fl ow of tient is a current wearer who uses fi nd it challenging to allow others information. Additionally, having monthly disposables and complains to help with the contact lens exam, a point person outside the exam of discomfort towards the end of it can free the doctor up to inves- room ready to relay any necessary their wear cycle, daily disposables tigate another concern, interpret directions can ensure clarity. or lenses made from more oxygen data from scans or even move on 2. Keep diagnostic lens banks up permeable materials are alterna- to the next patient. Encouraging to date. Not having the necessary tives the technician could suggest. your contact lens technicians to diagnostic lens in your stock means On the other hand, if the patient gain further education with contact that certain patients cannot be has never worn contact lenses be- lenses and achieve certifi cation fi t—and if they’re already waiting fore, the technician can ask them allows them to record patient in the exam chair, this constitutes a the during the pre-test if they’ve history, assess lens fi ts and perform serious problem. Thus, when train- ever considered trying them, and overrefractions, potentially even ing staff members on contact lens to talk to the practitioner if they’re

REVIEW OF CORNEA & CONTACT LENSES | MAY 2016 37

037_RCCL0516_PP.indd 37 4/25/16 2:06 PM Practice Progress By Mile Brujic, OD, and Jason Miller, OD, MBA

Boost Your Contact Lens Fits with Help from Your Staff

(Continued from page 37.) Source: QuickMBA.com Product Life Cycle Graph interested. Ask the technician to make a note in the patient’s chart if this is the case, so that the desire can be followed up on. The techni- cian may also be the ideal person to provide the patient with contact lens fi tting fees and annual wear cost estimations. For the practitioner, the key to a successful visit is for them to Sales Product listen to the patient’s concerns, their needs and desires for a contact lens. Always offer them the best lens choice to meet those Introduction Growth Maturity Decline requirements, but also consider individualizing prescribing habits When promoting contact lenses, be cognizant of where each falls on the to meet a patient’s lifestyle, even product life cycle to position it appropriately to patients. Is the lens new and innovative, or established and tried-and-true? Both have appeal, but should if they don’t explicitly ask for it. be presented diff erently. All products, including contact lenses, follow a Let them know you wish to ensure typical growth pattern. When fi rst introduced, sales initially grow at fairly their lenses are the clearest and standard, projected rate before exponentially taking off (the growth phase), most comfortable option for their as the product’s design continues to be fi nessed. Upon reaching maturity— characterized by the product’s achievement of a solid design and consumer circumstances and, above all, state base—sales then start to decline as consumers fi nd new alternatives. In time, the expectations for success up however, consumers will become reinterested, and the cycle will begin again. front. They may thank you. If the patient does not opt to cooperation towards the end goal of CONSIDERING move forward with contact lens growing the contact lens business. THE ENVIRONMENT wear, have your opticians make Each staff member should extend In addition to strengthening your one fi nal offer. Consider quickly the offi ce philosophy in each patient staff’s education, offer them the re-evaluating your protocol and encounter, delivering a consistent chance to work with the most make that offer while they are message. Take note: this does not innovative products. Though some choosing frames. A study ana- mean that everyone in the offi ce diagnostic equipment may be re- lyzing the fi tting process with needs to be an expert in contact served for those patients who are non-contact lens wearers found lenses; rather, they should simply complaining of symptoms, many that fi tting all suitable patients be kept aware of the fi tting process who present simply looking to with contact lenses prior to specta- and the newest lens technologies refi ll their old prescription can also cle dispensing not only makes the available. This approach may help benefi t. Patients are often busy frame selection process easier, but you own the contact lens market in in their own world and are not also is a good way to get patients your area. RCCL up to date on events or develop- interested in contact lenses.2 1. Rumpakis, John MB. New Data on Contact Lens ments in contact lens technology. Dropouts: An International Perspective. Review of This allows for an opportunity to n conclusion, communication is Optometry, 2010 Jan. not only demonstrate the newest vital. Constant communication 2. Atkins NP, Morgan SL, Morgan PB. Enhancing I the approach to selecting eyewear (EASE): a advancements to the patient, but between all members of the offi ce multi-centre, practice-based study into the eff ect also for staff members to use these staff—from the receptionist to the of applying contact lenses prior to specta- cle dispensing. Cont Lens Anterior Eye. 2009 pieces of equipment. practitioner—will enable better Jun;32(3):103-7.

38 REVIEW OF CORNEA & CONTACT LENSES | MAY 2016

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