Eyeworld

EW CATARACT 28 June 2011 by Michelle Dalton EyeWorld Contributing Editor Combining cataract and keratoconus treatment Lens calculations are not as easy in this group of patients, but a carefully planned strategy can yield optimal visual results P atients who have both cataract and keratoconus present some unique chal- lenges for the surgeon, in- cluding lens choice and general IOL calculations. Oftentimes in these eyes, measured Ks are not as accurate as manual keratometry can be. Toric lenses may be helpful, but they, too, have limits in this patient group. "The best results from toric IOLs come from patients who have regu- lar, symmetric, and stable corneal astigmatism," said Uday Devgan, M.D., chief of ophthalmology, Olive View – University of California, Los Angeles Medical Center, Sylmar, Calif., and Devgan Eye Surgery, Los Angeles. "If the corneal astigmatism is irregular, asymmetric, or unstable, then the results will not be nearly as good or predictable." Robert M. Jaffee, M.D., Jaffee Eye Associates, Middletown, N.Y., re- cently saw a 50-year-old patient with both cataract and keratoconus. As he noted, "The patient is –9.50 OD [right eye], –14.50 OS [left eye]. The K readings are 44.50x46.50 OD and 44.25x50.00 OS. Further, he has a posterior subcapsular cataract OS but only trace OD and has 20/20 vision in the OD." Dr. Jaffee said this par- ticular patient used contact lenses (–8.00 on the OD). The first question to address in patients like this is whether or not to even use a toric lens, and if you do choose to use a toric lens what the post-op refractive error should be, Dr. Devgan said. For Stephen S. Lane, M.D., ad- junct clinical professor, University of Minnesota, Minneapolis, the funda- mental question is even more basic: "Is this a person who is going to have cataract surgery in both eyes? That determination alone will make a difference in how you approach treatment." Noting there are "several discus- sion points" in patients like these, Eric D. Donnenfeld, M.D., clinical professor of ophthalmology, New York University Medical School, New York, said determining what the true K value is and how to manage the patient's astigmatism have to be the primary concerns. "In this example, the Ks aren't too irregular—they're both below 50. In patients with more severe ker- atoconus, it can create a problem," he said. Dr. Devgan said if the patient can be refracted to good vision with a phoropter and "the central cornea is relatively symmetric and regular, the patient will likely do well with the toric IOL. But if the patient does- n't see well with glasses and requires hard contact lenses for best vision, then be very careful—these patients can have unpredictable results from a toric IOL." Another pearl for clinicians—if the cornea's irregularity is on the pe- riphery but the central cornea is symmetric and normal, likely the patient will do well in toric lenses, Dr. Devgan said. "Another way to look at it is, when patients are out of contacts, can they see sharply with glasses? Glasses can only fix regular, sym- metric astigmatism, which is the same as with a toric IOL. The only thing that can fix irregular or asym- metric astigmatism is hard contact lenses," he said. If both eyes are likely to un- dergo cataract surgery in the near fu- ture, Dr. Lane suggested "trying to shoot for the best uncorrected visual acuity you can get, a lot of which will depend on the state of the kera- toconus." If keratoconus is ad- vanced, surgeons should consider deep anterior lamellar keratoplasty or a full corneal replacement before the cataract removal. Dr. Lane ad- vised considering a toric IOL only if the keratoconus/topography has been stable over several years. "The problem with using a toric IOL is that when you correct corneal astigmatism with a lenticular solu- tion, if the cornea changes, you're trying to correct the corneal and lenticular astigmatism that you've induced with a toric lens. You'll need a bitoric contact lens to correct and compensate for this," he said. A conservative approach would be to treat with a monofocal IOL and cor- rect any residual cylinder with a contact lens, he said. Determining the axis and other pearls With K values that can "vary widely over a small area of the cornea," Dr. Donnenfeld tells patients their re- fractive results may be suboptimal. He does, however, recommend using the ORange (WaveTec, Aliso Viejo, Calif.), an intraoperative aberrome- ter that's been on the market for about a year. "The ORange takes an intraoper- ative reading in the patient's aphakic state and will tell you what IOL power is best," Dr. Donnenfeld said. For patients who previously under- went LASIK or who have kerato- conus, "an intraoperative reading is particularly helpful." He said some surgeons advocate performing an aphakic refraction on the day of sur- gery and then taking the patient back to the OR to place the IOL. Presbyopia continued from page 27 sual axis is not the center of the pupil." In order to ensure you're im- planting the ReSTOR in the right spot, Dr. Tipperman suggested using fixation glasses from Mastel (Rapid City, S.D.), which consist of a high- powered magnifying glass with an LED light attached to the center of the nose. During the pre-op exam, have the patient look at you and mark where the light reflects on the patient's cornea. "It allows the surgeon to see on the cornea where the true visual axis is," said Dr. Tipperman. "When I'm done with the surgery and I'm about to center the ReSTOR lens, I don't have to guess." No matter which IOL is your fa- vorite, it's important to choose the best one for the patient. Patients are more educated than ever these days and may come into the office with some preconceived notions. "The fact that the patient wants it is on the bottom of my list of rea- sons of why I would recommend a lens," said Dr. Tipperman. "Patients have to have a good biometry, a healthy eye, and a solid understand- ing of what's involved." EW Editors' note: Dr. Chu has a financial interest with Bausch & Lomb. Dr. Tipperman has a financial interest with Alcon. Dr. Trattler has a financial in- terest with AMO. Contact information Chu: 952-835-0965, yrchu@chuvision.com Tipperman: rtipperman@mindspring.com Trattler: 305-598-2020, wtrattler@gmail.com A patient with keratoconus An example of a patient with kerato- conus; the bulging cornea is obvious A patient with keratoconus, with the steep curvature identified Source: Uday Devgan, M.D.

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