Special Considerations in Cataract Surgery: Five Cornea Challenges
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Clinical Update EXTRA CONTENT AVAILABLE CATARACT Special Considerations in Cataract Surgery: Five Cornea Challenges by linda roach, contributing writer interviewing preston h. blomquist, md, rosa a. braga-mele, md, kimberly a. drenser, md, phd, herbert e. kaufman, md, marguerite mcdonald, md, and roger f. steinert, md s the most common surgical choices, said Marguerite McDonald, IOL Selection procedure in ophthalmol- MD, of Lynbrook, N.Y. The device en- ogy, replacement of a cloudy ables the surgeon to directly measure 1 crystalline lens with an the eye’s aphakic refractive power in intraocular lens (IOL) usu- the operating room. Aally presents the ophthalmologist with Using intraoperative aberrometry is familiar sets of surgical routines. But becoming more commonplace, as “it what about those cases that involve may help in achieving more accuracy comorbidities or other complicating with IOL power selection,” Dr. Mc- factors? Donald said. Several experts shared their per- Tips on IOL selection. The chosen spectives on approaching out-of-the- IOL should be shaped to neutralize After an off-center LASIK procedure ordinary cataract surgeries in ways spherical aberrations, said Rosa A. such as this, the irregularity of the that offer the best chance at optimiz- Braga-Mele, MD, at the University of corneal topography indicates that a ing patient outcomes. This month, Toronto. “In anybody who has had multifocal IOL should be avoided. here’s a look at five challenges involv- myopic LASIK or PRK, I think it’s very ing the cornea. important to use a negatively aspheric prior to cataract surgery. 2) A dysfunc- IOL, because these patients have more tional, unstable tear film will affect the Challenge: Prior Refractive Surgery positively aberrant corneas. You don’t visual outcome by introducing error Two decades after the first corneal re- want to use a standard IOL, which will into the measurements on which the fractive surgeries in the United States, increase their aberrations.” IOL power calculations depend, Dr. many laser- or RK-sculpted eyes are Multifocal IOLs also should be Steinert noted. “Mild to moderate dry now developing cataracts. These ablat- avoided. “A multifocal IOL is usually eye can disrupt the tear film enough to ed or weakened corneas defy conven- not recommended for [most of] these affect the optics of the cornea.” tional formulas for determining IOL patients, because the cornea is already Diagnostic clues. “The first step power, said Roger F. Steinert, MD, at multifocal,” Dr. McDonald said. is recognition. It is easy to overlook a the University of California, Irvine. case of mild to moderate dry eye, par- Avoid IOL power errors. Dr. Stein- Challenge: ticularly if the patient is asymptom- ert recommends adjusting IOL power An Unhealthy Ocular Surface atic,” Dr. Steinert said. calculations for postrefractive surgery It’s essential to ensure that the ocular Stepwise use of standard diagnostic eyes with the aid of a free online tool.1 surface is as healthy as possible before tools, such as the Schirmer test of tear “You put in all the info you have about surgery, said Dr. Steinert, for two rea- production, has been proposed by two the eye, and it gives you IOL power sons. 1) Dry eye syndrome and related expert consensus panels.2,3 Dr. Steinert recommendations using as many for- surface-damaging disorders are likely favors corneal staining with lissamine mulas as it can.” It is then up to the to worsen if they are not addressed green or rose bengal, as these agents surgeon to choose from among them. Alternatively, many surgeons use Special Considerations in Cataract Surgery is an occasional series on challenging an intraoperative aberrometer, the situations in cataract surgery. Future installments will cover such topics as cataract Optiwave Refractive Analysis system, surgery in the settings of other comorbidities, such as age-related macular edema, courtesy of roger steinert, f. md to improve the accuracy of their IOL glaucoma, and diabetic retinopathy. eyenet 27 Cataract can reveal more subtle surface damage 2 alert to subtle clues that herpes simplex than fluorescein staining can. virus type 1 (HSV-1) infection of the For meibomian gland dysfunction cornea might be the real cause of a (MGD), the key signs are meibomian patient’s reduced acuity, said Kimberly gland dropout, abnormal secretions A. Drenser, MD, PhD, of Royal Oak, when the glands are expressed, and Mich. If this is the case, there will be a changes in lid morphology.3 To detect mismatch between the severity of the blepharitis, it is important to examine cataract and the patient’s visual com- the eyelids and exert mild pressure on plaints. the central third of the lower eyelid to A need for suspicion. When it look for signs of meibomian gland in- comes to HSV-1, cataract surgeons spissation, Dr. McDonald added. BACTERIAL RESISTANCE. MRSA kera- cannot afford to let down their guard. Postpone surgery as needed. Sur- titis with hypopyon in a health care If the virus progresses unnoticed, it gery should be postponed until any worker after sutureless cataract sur- can cause a necrotizing infection that surface damage has been treated and gery. “really wipes out the retina,” said Dr. resolved as much as possible, which Drenser. usually takes two to four weeks, Dr. it takes for the cornea to unmold, so In addition, researchers now sus- Steinert said. that preop biometry is accurate. This pect that most patients—although Make better use of artificial tears. means at least two consecutive visits they may seem uninfected at the Dr. Steinert said that his dry eye pa- where the manifest refraction and to- time—carry HSV-1 in their systems tients get the most benefit—both pre- pography maps are virtually the same,” that could become active if their im- and postoperatively—from artificial Dr. McDonald said. She added, “If the munity were sufficiently compromised tears if they instill preservative-free patient is wearing gas-permeable or by surgery, said Herbert E. Kaufman, tears both liberally and, importantly, soft toric lenses, they should be out MD, at Louisiana State University (see before they experience any discomfort of them for at least one month—and “More Online,” below). related to their dry eye disease. out of soft spherical lenses for three The prophylaxis problem. Periop- Intraoperative tips. Dr. McDonald weeks—before they return for the erative prophylaxis, sometimes with offered the following intraoperative first of at least two visits. I will wait as immunosuppression, in people with tips to help protect the surface from long as necessary to be sure that their prior HSV keratitis remains prudent, surgical stress and minimize the corneas have unmolded and are finally said Dr. Kaufman. However, there still chances of dry eye symptoms after stable.” are no good data on what works best surgery. Reduce astigmatism. The kerato- before cataract surgery. • Use a topical viscoelastic. “Many conic patient will have better pseudo- In general, Dr. Kaufman’s herpes surgeons use viscoelastic on the cornea phakic acuity if the keratome incision prophylaxis regimen is similar to the as a way to keep the eye moist during is placed on the steep axis to reduce one followed by many LASIK sur- cataract surgery,” she said. regular astigmatism, Dr. McDonald geons in patients with prior herpetic • Take care with the speculum. said. Manifest refractions and topo- infections.4 The intensity of the regi- “Opening the speculum only as much graphic maps should be obtained to men (outlined below) varies based on as is necessary, and not more, helps locate the axis accurately, she said. In the prior infection site in the eye, on to avoid lagophthalmos and exposure addition, a toric IOL also is appropri- whether active disease develops despite keratitis postoperatively. These flaccid ate for a keratoconic patient, because prophylaxis, and on the degree of ocu- older lids don’t recover so easily from it can improve postcataract acuity in lar inflammation, he said. the stretching and trauma they receive selected eyes, Dr. Braga-Mele said. He considers the most serious when the speculum is cranked open Rethink cross-linking. “Most kera- threats to vision from HSV-1 to be se- wide,” she said. toconus patients with cataracts are vere inflammation, iritis, and stromal older and their keratoconus is stable; keratitis. “I don’t want the immune re- Challenge: Keratoconus therefore, they will not need cross- sponse in the eye to be too severe, and The experts offered the following tips linking,” Dr. McDonald said. “If they I don’t want the inflammation to dam- for patients with keratoconus. are younger and the keratoconus is still age the endothelial cells of the cornea.” Discontinue contacts. Because of changing, it is best to do cross-linking Prevention and treatment tips. Dr. their highly aberrated corneas, many first, let the cornea stabilize, and then Kaufman offered the following tips patients with keratoconus use cus- do the cataract surgery.” on preventing recurrence and treating tomized, rigid gas-permeable contact new disease. lenses, which mold their corneas to Challenge: Herpes Infections • Preventing recurrence in cases of compensate for the optical distortions. When examining patients before cata- stromal disease or iritis. Before sur- “Stop contact lenses for as long as ract surgery, the clinician should be gery, Dr. Kaufman prescribes one or courtesy preston of md blomquist, h. 28 may 2014 Cataract two days of oral valacyclovir hydro- tant bacteria from entering the eye and 3 Invest Ophthalmol Vis Sci. 2011;52(4). Free chloride (Valtrex), typically given in causing endophthalmitis. download in multiple languages at www. doses of 500 mg, three times a day.5 A need for suspicion. Certain pa- tearfilm.org/tearfilm-reports.php. The medication is then continued for tients are at increased risk of carrying 4 de Rojas Silva V et al.