Anyone, even more so an editor, who steps into the ring to discuss a controversial topic must expect to take a few hits, so here are some comments about a JCRS editorial1 from the surface ablation side.
The most important thing to remember is that the downsides to photorefractive keratectomy (PRK)—pain and haze—were a problem of old technology. By the time the technology improved, few surgeons were still doing surface ablation, so the myth persists. In reality, in a PRK practice today, pain occurs in only 4% of eyes (personal experience with more than 1000 PRK procedures per year for 10 years) and is easily managed with dilute topical anesthetic agents (now known to be less toxic than steroids to regenerating epithelial cells). Using a bandage contact lens and a nonsteroidal agent, the norm is mild to moderate discomfort and, yes, you can now have PRK and laser in situ keratomileusis (LASIK) postoperative patients in the same room.
Haze after surface ablation in patients with low and moderate myopia is symptomatic in fewer than 1% of patients.2 In those with high myopia, depending on the use of cold techniques and mitomycin-C, haze occurs in 2% to 5% (H.A. Lane, MD, P.A. Majmudar, MD, “Prophylactic Mitomycin-C for High-Risk PRK,” Cataract and Refractive Surgery Today, supplement to April 2002, pages 31–32; A.V. Zolotaryov, MD, presentation at the annual meeting of the American Academy of Ophthalmology [AAO], Orlando, Florida, USA, October 2002; F. Carones, MD, presentation at the AAO annual meeting, New Orleans, Louisiana, USA, November 2001; D.R. Edmison, MD, “Results of Intraoperative Mitomycin-C in 97 PRK Eyes Over 2 Years,” presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, Philadelphia, Pennsylvania, USA, June 2002). Most of these can be treated with steroids and in the few who need phototherapeutic keratectomy (PTK), haze can be eliminated. Contrary to the myth, haze does not get worse after retreatment with PTK if done properly. I would gladly trade grade 4 haze for a recalcitrant epithelial ingrowth under a flap.
Photorefractive keratectomy never stood a fighting change because of U.S. Food and Drug Administration regulations in the early 1990s. It was never abandoned, just bypassed by LASIK, which was the only refractive game in town. In many ways, this has not served the best interests of patients as LASIK has, in part, been driven by better marketing advantages and the safety issues have been overlooked. The safety advantages with surface ablation are well established and do not have to be elaborated. Retreatment rates for PRK are now only 1% to 4% (Bruce Jackson, MD, personal communication, January 2003)2 and wavefront-driven treatments appear better with surface ablation (without a flap covering the detail) (M.B. McDonald, MD, Binkhorst Lecture, presented at the AAO annual meeting, New Orleans, Louisiana, USA, November 2001).
For the high-altitude example, would you rather deal with a patient who developed steroid-responsive ultraviolet-induced haze a month after his or her trip or a patient who experienced significant vision loss on a mountain due to flap desiccation and instability?
David R. Edmison MD
Ottawa, Ontario, Canada
1. Kohnen T. Lamellar or surface? [editorial]. J Cataract Refract Surg 2002; 28:1305-1306
2. Stevens J, Giubilei M, Ficker L, Rosen P. Prospective study of photorefractive keratectomy for myopia using the Visx StarS2 excimer laser system. J Refract Surg 2002; 18:502-508