Eyeworld

EW CORNEA 26 November 2011 The problem here, Dr. Potter said, is that access to crosslinking is limited in the U.S. to clinical trials, but it is widely available in Europe, Mexico, and elsewhere. "Patients may be uncomfortable going to a doctor they have never seen before or traveling to another country," Dr. Potter said, adding that patients are often willing to make the journey because they unrealisti- cally believe that the procedure will be the cure. "Every patient I know who has had collagen crosslinking anticipates that the treated eye will get better, no matter how much the doctor tells the patient it's to stabilize it. Pa- tients all think that they're going to get better," Dr. Potter said. "We have to manage the patients' expectations in a humane way. We have to say, 'I know you want this to get better, but I would be remiss if I didn't tell you it's probably not going to.'" Dr. Hardten said follow-up might be the first compassionate step. "If it's the first time the patient hears that he has inferior steepen- ing, for example, he needs to process that information in his head and ab- sorb the fact that he has this specific diagnosis. That's where serial topog- raphy and tomography in 6 months or a year to see whether it's progres- sive might make sense," he said. But when? Another big dilemma for surgeons remains. When should the treat- ment be administered? A. John Kanellopoulos, M.D., associate clinical professor of oph- thalmology, New York University, New York, and director of laser vi- sion, GR Institute, Athens, Greece, is a leader in the field and agreed that there is no set measure for when a patient should be sent for treatment. "The indication for crosslinking is constantly evolving," Dr. Kanellopoulos said. "We started crosslinking cases that had 'danger- ous ectasia' as a desperate interven- tion to avoid penetrating keratoplasty. This dates back 10 years." Dr. Kanellopoulos said 10 years of study have established that crosslinking has the ability to in- crease the biomechanical stability of the cornea. "At the same time, once the level of efficacy has established it- self, we're looking at expanding the indications to, for instance, a 17- year-old with significant kerato- conus," he said. "Most clinicians in Europe would agree today that that patient would be a candidate for crosslinking, and we would not wait for the ectasia to become worse to employ crosslinking." Yaron S. Rabinowitz, M.D., clinical professor, University of Cali- fornia, Los Angeles, and Stephen D. Klyce, Ph.D., Mount Sinai School of Medicine, New York, have estab- lished traditional guidelines for the diagnosis of keratoconus, which in- volve symmetry between the eyes, inferior steepening, and taking data just over and under the center of the cornea and determining whether the inferior cornea is steeper, Dr. Kanellopoulos said. "Cornea tomography today of- fers much more data looking at the Belin/Ambrosio protocol on the Pentacam [Oculus, Lynnwood, Wash.]," Dr. Kanellopoulos said. "There are all these parameters that have evolved suggesting ectasia or progression of ectasia." There may be different types of ectasia in different populations, he added. "We know that in Greece, for in- stance, probably 1 in 100 young males has some form of kerato- conus, which is an astounding statis- tic considering that the western bibliography sets that number to about 1 in 10,000." Traditionally, intervention was withheld in these young patients if their visual acuity was good because younger keratoconic patients tend to see better because the optical system is flexible, which bypasses signifi- cant irregularities of the cornea, Dr. Kanellopoulos explained. "We pay more attention to the corneal thickness, the distribution of the corneal pachymetry going from the center of the cornea to the pe- riphery," he said. "If there is skewing of the way the cornea becomes thicker as we go from the center to the periphery, this is suggestive of keratoconus. Given all the data, there are still no concrete guidelines of what is keratoconus, what is ecta- sia, and what is the threshold that we should intervene. There's a Euro- pean consensus that we would offer crosslinking to a patient who is under 45 and has keratoconus, re- gardless of whether we had estab- lished that keratoconus was progressive or not. That's universal to everyone." Dr. Kanellopoulos said crosslink- ing also would be offered to post- LASIK ectasia patients because their disease may progress. He said the traditional Dresden protocol of a minimum of a 400-mi- crometer corneal thickness often should be used because someone who is under 400 micrometers risks endothelial toxicity from the proce- dure. "We've pushed that border to 350 micrometers or 300 micrometers as a compassionate use in some pa- tients where their only alternative was penetrating keratoplasty. We've shown some of those cases that crosslinking can be employed with caution in thinner corneas as a last- resort treatment," Dr. Kanellopoulos said. "Obviously, we would strongly encourage that if someone was to undergo crosslinking, it would be optimal of it was done with thick- nesses over 400 micrometers." Finally, the hardest part of the decision-making process is deciding what to do with the patient's better eye, Dr. Potter said. "The theory I like to work from is how can I make patients' lives bet- ter? If I can make their lives better by reducing the risk that they get worse, that's not a bad thing," he said. EW Editors' note: Dr. Hardten has financial interests with Avedro and TopCon Corp. Dr. Kanellopoulos has financial inter- ests with Alcon (Fort Worth, Texas). Dr. Potter has no financial interests related to this article. Dr. Probst has no finan- cial interests related to this article. Contact information Hardten: 612-813-3632, drhardten@mneye.com Kanellopoulos: +30-210-74-7277, ajk@laservision.gr Potter: 636-534-2300, john.potter@tlcvision.com Probst: 708-562-2020, leprobst@gmail.com How continued from page 25 O n Sept. 23, as a follow-up to a May 2009 letter, the FDA issued another letter to eyecare professionals regarding the advertis- ing and promotion of FDA-approved lasers used in refractive procedures. Both letters are in response to "information" re- ceived at an April 2008 Ophthalmic Devices Panel public meeting that "eyecare professionals' advertising and promotion often failed to properly inform consumers of the indications, limitations, and risks of refractive procedures and the lasers used for those procedures." The FDA noted that any corrections should be made within 90 days to avoid regulatory action. The FDA's LASIK website, www.fda.gov/ Med- icalDevices/ProductsandMedicalProcedures/SurgeryandLifeSupport/LASI K/default.htm, contains a list of all FDA-approved lasers for refractive procedures, the intended uses, and any associated risks of each approved laser. FDA issues letter on promotion and advertising of lasers used in refractive procedures Corneal riboflavin (stromal fluorescence) penetration through intact epithelium Source: Brian S. Boxer Wachler, M.D.

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