25 years of refractive surgery needs

Refractive pioneer offers slant on proper patient selection

PRK, a refractive surgery option for 25 years. Here, post-PRK eye with minor epithelial separation
Source: Dajlit Singh, M.D.

For practitioners these days, there seem to be a plethora of refractive choices from various laser surgeries, such as PRK and LASIK with or without wavefront to options such as conductive keratoplasty (CK). Sometimes the challenge can be in determining which patients are best served by a given refractive procedure. One pioneering practitioner, Marguerite B. McDonald, M.D., clinical professor of ophthalmology, New York University, School of Medicine, New York, and adjunct professor of ophthalmology, Tulane University Health Sciences Center, New Orleans, has been at the forefront of many of these innovative refractive procedures.
It all began 25 years ago with the advent of PRK. Dr. McDonald reflects on these early days. “Initially, of course, we did plastics and then cadaver animal eyes then cadaver human eyes, then countless living rabbits and monkeys,” she said. “Then, finally there was the very first human eye.” This was one that was scheduled for removal due to a deadly conjunctival malignant melanoma. “The patient could see perfectly,” Dr. McDonald said. “Very incredibly she asked, ‘If I’m going to lose my eye and be massively disfigured in 11 days, would somebody like to do an experiment on that eye before it is removed?’ So, we did the first human eye.” This was followed by experiments with blind eyes, partially sighted ones, and then fully sighted patients.
Dr. McDonald made her own inroads with the LASIK procedure when she became the first practitioner in the United States to perform a wavefront-guided procedure. She also helped to add epi-LASIK to the equation as the first North American practitioner to perform the procedure. “Epi-LASIK was an attempt to do surface ablation but with less pain and speedier return of vision,” Dr. McDonald said. “It was actually designed to be the best of both worlds—the safety of PRK and the lack of pain and speedy return of vision that you find with LASIK.”

Waning procedures

While the custom wavefront approach continues to prevail, epi-LASIK has hit some bumps along the way. “It is still done in pockets here and there, but the popularity has waned because these mechanical devices can occasionally give you a stromal incursion,” Dr. McDonald said. “Also, peri-operative regimens with PRK have become so much better now, and pain and return of vision are almost equal with LASIK now.” In addition it can be difficult to secure the needed equipment for epi-LASIK. “Norwood Abbey [a company that made epi-LASIK equipment] got out of the business, so it’s hard to find an epi-keratome these days,” Dr. McDonald said.
Likewise, use of CK has declined a bit due to some company woes. “The original company that made it was Refractec [Irvine, Calif.]; ... they came up with a template which really makes CK easy and reproducible and safe,” Dr. McDonald said. “It[Refractec] was rescued [financially] ... so, CK lives even though you don’t see big marketing campaigns for it anymore.”

Patient selection

For many of these refractive procedures, there can be considerable overlap in desired results, leaving it to the practitioner to make a judgment call as to which is likely to best serve a specific patient. Deciding whether it is LASIK or PRK has the edge often rests on several factors. “First you look at the patient physically to see if they have a cornea that’s thicker,” Dr. McDonald said.
The actual shape of the cornea may also play a role. “With mechanical microkeratomes for LASIK, corneas that are too steep or too flat have to have PRK because they don’t do well with the microkeratome, and complications can occur,” Dr. McDonald said. “Now with the IntraLase [Advanced Medical Optics, Santa Ana, Calif.], it is said that very flat very steep corneas don’t matter so much, although these are considerations.”
Concerns about complications, particularly on retreatments, are another issue. “Most people are slowly but surely turning to surface ablation on top of LASIK flaps for enhancements because the incidence of epithelial ingrowth is so much higher on reoperation and relifting the flap,” Dr. McDonald said.
The patient’s own lifestyle can also be a factor. Sometimes a hobby or profession can tip the scales one way or the other. “If they’re a wrestler and they’re likely to get a thumb in their eye, perhaps LASIK is not a good choice for them, and they would be better having PRK because you don’t want that LASIK flap to be ripped up by a fingernail,” Dr. McDonald said.
Also important to consider are what ramifications the procedure might have for the patient. For example, some employers such as airlines or the military may still frown on LASIK but be perfectly fine with PRK in its stead. “If the patient wants to join United Airlines as a pilot, they have to check with United whether LASIK or PRK are acceptable,” Dr. McDonald said. “The onus is on the patient.”
Overall, Dr. McDonald sees a bright future for laser vision correction. “I think that laser vision correction on the cornea will be around for a very long time if not forever,” she said. One caveat that she does envision is that with the recent emergence of phakic IOLs, these will be of increasing importance for those with more severe myopia and hyperopia. “I think LASIK and PRK will be around for a long time and are improving, but the more extreme prescriptions will now be addressed with intraocular surgery,” Dr. McDonald said.

Editors’ note: Dr. McDonald has financial interests with Advanced Medical Optics (Santa Ana, Calif.), Allergan (Irvine, Calif.), Bausch & Lomb (Rochester, N.Y.), Inspire (Durham, N.C.), Oasis Medical (Glendora, Calif.), and Santen (Napa, Calif.).

Contact Information
McDonald: 516-593-7709, mbm2626@aol.com