THE LITERATURE s THERAPEUTIC REFRACTIVE SURGERY IN Investigators are expanding treatment options to improve and corneal stability in patients with keratoconus.

BY JASON R. MAYER, MD; AND RAVI H. PATEL, MD

FEMTOSECOND -ASSISTED STROMAL LENTICULE distance visual acuity (CDVA), manifest refraction, and ADDITION KERATOPLASTY FOR THE TREATMENT OF topography. ADVANCED KERATOCONUS: A PRELIMINARY STUDY Six months after surgery, UDVA had improved signifi- cantly from 1.58 ±0.36 to 1.22 ±0.37 logMAR (P = .024), and Mastropasqua L, Nubile M, Salgari N, Mastropasqua R1 CDVA had improved from 1.07 ±0.17 to 0.70 ±0.23 logMAR (P = .007). All study eyes showed generalized flattening at ABSTRACT SUMMARY 6 months, with a change in mean anterior keratometry When spectacles or contact lenses fail to provide useful values from 58.69º ±3.59º before surgery to 53.59º ±3.50º. visual function, surgical intervention may be the only means Central corneal thickness increased from a mean of by which to improve the visual acuity of a patient with ker- 406 ±42 µm preoperatively to 453 ±39 µm at 6 months. No atoconus.2-5 Procedures to correct keratoconus include pen- immediate perioperative or long-term complications related etrating or deep anterior lamellar keratoplasty, intrastromal to SLAK were observed. corneal ring segment implantation, and CXL combined with PRK or phototherapeutic keratectomy (PTK). DISCUSSION The introduction of small-incision lenticule extraction to Studies have validated the integration and survival correct led to a hypothesis that stromal len- of transplanted refractive lenticules in host .6-8 ticules could be preserved and implanted to reverse refrac- Ganesh and Brar expanded on this work when they tive treatment or to treat other forms of ametropia. The implanted a doughnut-shaped myopic lenticule around goal of a novel surgical technique called stromal lenticule the cone and midperiphery to induce a less hyperprolate addition keratoplasty (SLAK) is to improve stromal thickness and induce central cor- neal flattening by implanting stromal lenti- cules in the eyes of patients with advanced keratoconus. STUDY IN BRIEF Mastropasqua and colleagues’ noncom- s A small, noncomparative, interventional case series investigated the effect of a novel parative interventional case series included treatment for advanced keratoconus: femtosecond laser–assisted stromal lenticule 10 eyes of 10 patients with stable stage 3 or addition keratoplasty (SLAK). The researchers found SLAK to improve visual acuity stage 4 central keratoconus. The procedure and corneal shape. by which a femtosecond laser cuts a stromal flap was modified to instead produce an intrastromal pocket around the marked cen- WHY IT MATTERS Treatment options for keratoconus continue to expand as investigators search for safe ter of the . Investigators then implant- ed negative meniscus lenticules previously and effective ways to improve affected patients’ quality of life. The results of this study prepared from donor corneas. The research- suggest that SLAK is a safe and clinically efficient method of improving corneal shape and ers measured postoperative uncorrected visual acuity in patients with advanced keratoconus. distance visual acuity (UDVA), corrected

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15,16 cornea in this patient population. patient population. in this cornea transepithelial PTK combined with conventional PRK and with conventional PRK and combined transepithelial PTK plus) in patients with progressive CXL (Cretan protocol combined procedure keratoconus. The researchers found the stabilizing the effective in improving UCVA and BCVA and to be Investigators evaluated the safety and efficacy of and efficacy of Investigators evaluated the safety 

s standard algorithm for the treatment of irregular There is no The investigators chose conventional instead of of instead conventional chose investigators The 14 WHY IT MATTERS in keratoconus during or after CXL. This study improve which to by and effective method demonstrated a safe cornea. acuity and stabilize the visual STUDY IN BRIEF Recent studies have shown that combining CXL with with CXL combining that shown have studies Recent Grentzelos and colleagues showed that the combined combined the showedthat colleagues and Grentzelos stable keratoconus. The majority of keratoconus cases keratoconus of majority The keratoconus. stable determineto needed is investigation Further eccentric. are study, this in used profile lenticule the with SLAK, whether keratoconus.eccentric with patients in effective and safe is tissue- this with CXL combining that proposed been has It and acuity visual improve further can approach addition keratoconus. of treatment the in analysis topographic After stromal thickness is increased with SLAK, patientsSLAK, with increased isthickness stromal After arereadings pachymetry whose keratoconus advanced with receivethen could CXL for values recommended the below suggested colleagues and Mastropasqua treatment. CXL inbeneficial be also might CXL with SLAK combining that treatmentthe expand would this keratoconus; progressive population.patient this for options a secondary procedure (eg, topography-guided PRK, PRK, topography-guided (eg, procedure secondary a phakic or implantation, segment ring corneal intrastromal UCVA. and BCVA improve can implantation) IOL encourag described study Cretan the from report earlier degeneration marginal pellucid with patients in results ing and PRK, PTK, transepithelial combined underwent who CXL. acts PTK transepithelial because PRK topography-guided epithelium thinner the given treatment, customized a as PTK 50-µm A eyes. keratoconic in apex the at apex, corneal the at stroma of amount small a removes protocol), (Cretan surface regular more a in resulting UCVA, improve significantly to shown been has which readings. keratometry and BCVA, DISCUSSION procedure can not only stabilize but also improve the the improve also but stabilize only not can procedure

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total. 2 10 Grentzelos and colleagues stud colleagues and Grentzelos 11 | SEPTEMBER 2018

Mastropasqua and colleagues implanted a negative a implanted colleagues and Mastropasqua 9 Among the limitations of the study are a smalla are study the of limitations the Among Six months after surgery, they found a statistically sig statistically a found they surgery, after months Six One year after treatment, mean UCVA had improvedhad UCVA mean treatment, after year One This prospective case series included 53 eyes of 43 patients43 of eyes 53 included series case prospective This Although CXL has been shown to strengthen the corneathe strengthen to shown been has CXL Although a reduction in anterior corneal curvature, an increase in in increase an curvature, corneal anterior in reduction a corneal in improvement an and thickness, corneal central values. sphericity and central only of inclusion the and size sample meniscus-shaped stromal lenticule to evaluate SLAK for thefor SLAK evaluate to lenticule stromal meniscus-shaped keratoconus. stable advanced, of treatment spherical and CDVA, UDVA, in improvement nificant in increase an showing eyes 10 of nine with equivalent, demon eyes All lines. Snellen 3 to 1 from ranging CDVA including analysis, topographic on improvement strated corneal morphology and cause relative flattening in six in flattening relative cause and morphology corneal eyes. corresponding improvement in mean steep and flat keratom flat and steep mean in improvement corresponding (51%)eyes 28 months, 12 at conclusion study’s the At etry. eyesseven Specifically, BCVA. of line 1 least at gained had lines,2 gained (16%) eyes nine lines, more or 3 gained (13%) neither(47%) eyes Twenty-six line. 1 gained (22%) eyes 12 and vision. of lines 2 lost (2%) eye One vision. of lines lost nor gained with a 30-minute irradiance of 5.4 J/cm 5.4 of irradiance 30-minute a with hadBCVA mean and logMAR, ±0.35 0.39 to ±0.63 0.98 from Additionally,logMAR. ±0.16 0.08 to ±0.23 0.20 from improved fromsignificantly improved equivalent spherical mean awith year, 1 at D ±2.81 -2.24 to preoperatively D ±4.00 -4.67 underwent epithelial removal via PTK using the Allegrettothe using PTK via removal epithelial underwent optical 6.5-mm A (Alcon). system laser excimer WaveLight spatula,a with mm 9 and 8 between to extended was zone receivedthey Next, performed. was ablation 50-µm a and maximuma using laser excimer the with PRK conventional ofdepth ablation maximum a and mm 5.5 of zone optical CXLunderwent patients Finally, µm). ±10 22 (average, µm 50 patients undergoing combined transepithelial PTK, conven transepithelialPTK, combined undergoing patients CXL. and PRK, tional years±7.9 30.8 of was age mean women); 13 and men (30 thick corneal preoperative average and years) 18–39 (range, patientsAll µm). 410–526 (range, µm ±29 467 was ness ABSTRACT SUMMARY signifi not does procedure the ectasia, progressive halt and acuity. visual improve cantly inoutcomes topographic and refractive, visual, 1-year the ied COMBINED TRANSEPITHELIAL PHOTOTHERAPEUTIC COMBINED TRANSEPITHELIAL PHOTOTHERAPEUTIC KERATECTOMY AND CONVENTIONAL PHOTOREFRACTIVE BY CORNEAL KERATECTOMY FOLLOWED SIMULTANEOUSLY PROTOCOL PLUS CROSSLINKING FOR KERATOCONUS: CRETAN Grentzelos M, Kounis G, Diakonis VF, et al CATARACT & REFRACTIVE SURGERY TODAY

16 s THE LITERATURE - - . 2014;40(9):1439-1445. . 2014;30(8):566-576. . 2017;33(9):610-616. . 2014;30(4):272-276. J Cataract Refract Surg J Refract Surg . 2012;119(9):1777-1784. J Refract Surg J Refract Surg . 2014;33(10):1071-1079. Cornea EDWARD MANCHE, MD Eye Center of Northern Colorado, Fort Collins [email protected] Financial disclosure: None Eye Associates of Central Texas, Round Rock [email protected]; Twitter @The_EyeGuy_MD Director of Cornea and Refractive Surgery, Stanford Laser Eye Center, Surgery, Stanford Laser Eye Center, Director of Cornea and Refractive Stanford University School of Medicine, Professor of Ophthalmology, [email protected] (Avedro) Financial disclosure: Consultant and research support California California     Financial disclosure: None  n n n RAVI H. PATEL, MD n n n 11. Kymionis GD, Grentzelos MA, Liakopoulos DA, et al. Long-term follow-up of corneal collagen cross-linking for follow-up of corneal collagen cross-linking MA, Liakopoulos DA, et al. Long-term 11. Kymionis GD, Grentzelos study. keratoconus—the Cretan with refractive collagen cross-linking (CXL) combined MA, Portaliou DM, et al. Corneal 12. Kymionis GD, Grentzelos plus. of corneal ectatic disorders: CXL procedures for the treatment ring segments implan after sequential intracorneal El-Khoury S, Chelala E, et al. Toric ICL implantation 13. Abdelmassih Y, 2-year follow-up. tation and corneal cross-linking in keratoconus: et al. Simultaneous conventional photorefractive keratectomy and corneal 14. Kymionis GD, Grentzelos MA, Plaka AD, corneal degeneration. collagen cross-linking for pellucid marginal GA, et al. Combined transepithelial phototherapeutic keratectomy and corneal 15. Kymionis GD, Grentzelos MA, Kounis collagen cross-linking for progressive keratoconus. VP, et al. Long-term results of combined transepithelial phototherapeutic kera 16. Kymionis GD, Grentzelos MA, Kankariya for keratoconus: Cretan protocol. tectomy and corneal collagen crosslinking SECTION EDITOR n n n n JASON R. MAYER, MD - - . Surv Ophthalmol . 2013;8(6):e67058. . 2012;53(8):4975-4985. . 2018;34(1):36-44. PLoS One J Refract Surg . 2015;34(10):1331-1339. Cornea Invest Ophthalmol Vis Sci | SEPTEMBER 2018 . 2017;40(1):3-14.

. 2011;17:3437-3449. Mol Vis n Cont Lens Anterior Eye . 2015;2:19. . 2016;3:2. . 2017;43(10):1257-1262. Eye Vis (Lond) Eye Vis (Lond) 8. Mohamed-Noriega K, Toh KP, Poh R, et al. Cornea lenticule viability and structural integrity after refractive lenticule 8. Mohamed-Noriega K, Toh KP, Poh R, et al. Cornea lenticule viability and structural extraction (ReLEx) and cryopreservation. with accelerated collagen cross-linking for 9. Ganesh S, Brar S. Femtosecond intrastromal lenticular implantation combined the treatment of keratoconus—initial clinical result in 6 eyes. keratectomy and conventional 10. Grentzelos MA, Kounis GA, Diakonis VF, et al. Combined transepithelial phototherapeutic keratoconus: Cretan protocol plus. photorefractive keratectomy followed simultaneously by corneal crosslinking for J Cataract Refract Surg 3. Parker JS, van Dijk K, Melles GR. Treatment options for advanced keratoconus: a review. 3. Parker JS, van Dijk K, Melles GR. Treatment options for advanced keratoconus: 2015;60(5):459-480. and deep anterior lamellar keratoplasty 4. Henein C, Nanavaty MA. Systematic review comparing penetrating keratoplasty for management of keratoconus. of the art of the technique and new 5. Mastropasqua L. Collagen cross-linking: when and how? A review of the state perspectives. after myopic ReLEx: a feasibility study of 6. Angunawela RI, Riau AK, Chaurasia SS, et al. Refractive lenticule re-implantation stromal restoration after refractive surgery in a rabbit model. correction: a non-human 7. Riau AK, Angunawela RI, Chaurasia SS, et al. Reversible femtosecond laser-assisted primate study of lenticule re-implantation after refractive lenticule extraction. of laser platforms. Studies with longer follow-up intervals intervals follow-up longer with Studies platforms. laser of com the of outcomes long-term the assess to needed are procedure. bined Mastropasqua R. Femtosecond laser-assisted stromal lenticule addition kerato 1. Mastropasqua L, Nubile M, Salgari N, a preliminary study. plasty for the treatment of advanced keratoconus: which type, which technique, which 2. Arnalich-Montiel F, Alió Del Barrio JL, Alió JL. Corneal surgery in keratoconus: outcomes? 1 month after treatment remained significant at all all at significant remained treatment after month 1 seen were improvements Similar intervals. follow-up mean keratometry, steep and flat mean to regard with many Although equivalent. spherical and astigmatism, is it astigmatism, irregular treating for exist techniques with conjunction in PTK transepithelial that noting worth range broad a using performed be can PRK conventional BCVA of patients with keratoconus. The statistically statistically The keratoconus. with patients of BCVA observed UCVA and BCVA in improvement significant CATARACT & REFRACTIVE SURGERY TODAY

18 s THE LITERATURE