LASEK, PRK debate continues

February 15, 2005

New Orleans—LASEK, in contrast to PRK, provides a good, stable flap, and as a result of that difference, LASEK has important advantages that include less pain, less regression, and less risk of haze, said Massimo Camellin, MD, at a refractive surgery lecture during the International Society of Refractive Surgery of the American Academy of Ophthalmology annual meeting.

New Orleans-LASEK, in contrast to PRK, provides a good, stable flap, and as a result of that difference, LASEK has important advantages that include less pain, less regression, and less risk of haze, said Massimo Camellin, MD, at a refractive surgery lecture during the International Society of Refractive Surgery of the American Academy of Ophthalmology annual meeting.

"A good, stable flap means less pain, and less pain means less epiphora, which can lead to contamination and an increased risk of haze," said Dr. Camellin, inventor of LASEK, and health director of SEKAL Rovigo Micro Surgery in Rovigo, Italy. "In addition, with a good, stable flap, there is less keratocyte apoptosis, which is an early event in the pathway to haze."

However, presenting an opposing view in a point-counterpoint discussion, Steven C. Schallhorn, MD, concluded that there are no compelling reasons to support use of LASEK over PRK.

Discussing the benefits of LASEK versus PRK, Dr. Camellin noted that his own experience shows LASEK is less painful than PRK. In fact, his analyses show that only about 1% of patients with myopia and 6.5% of those with hyperopia who undergo LASEK report significant pain on the first day after surgery, he said.

LASEK is associated with less pain in part because the epithelial flap protects against stimulation of nerve endings in the stroma. However, meticulous surgical technique is needed to maximize the benefit of LASEK.

"Care must be taken to avoid ethanol leakage that can lead to pain from conjunctival irritation, and the eye must be covered with an adequately sized bandage contact lens postoperatively to keep the flap immobile," he said. "In addition, removing all of the fluid from under the flap is important to reduce flap mobility that can lead to pain."

Dr. Camellin has also found haze is less frequent after LASEK compared with PRK. Part of the reason for the difference is that after LASEK, the cascade of cellular events leading to scarring is mitigated. He explained that epithelial injury results in release of a variety of cytokines such as soluble Fas ligand and interleukins that promote apoptosis of keratocytes in the anterior stroma and cause inflammatory cells to migrate to the cornea. Proliferating keratocytes release additional chemical mediators that are thought to cause transformation of migrating keratocytes into myofibroblasts.

"These events are unavoidable in PRK and if something goes wrong, myofibroblast generation is increased with the development of more severe haze. In LASEK, however, the epithelial flap protects the stromal keratocytes from the chemical mediators released by epithelial injury so that keratocyte apoptosis and subsequently the pathway to haze formation are reduced," he explained.

Analyses of his own LASEK patients show that only 0.7% of patients with myopia and 1.1% of those with hyperopia have developed grade 2 haze.

Dr. Schallhorn noted that when LASEK was first introduced, it was touted as combining the best of LASIK and the best of surface ablation without any of the disadvantages of those techniques.

"In other words, LASEK was claimed to provide rapid visual recovery without pain. However, LASEK is no longer being compared with LASIK, because it doesn't compare well. Patients do not get the same fast visual recovery after LASEK as they do after LASIK," Dr. Schallhorn said.

He told attendees that LASEK is really much more like PRK than it is like LASIK. However, PRK has many advantages compared with LASEK because it requires less equipment, is a faster procedure, and avoids issues of ethanol toxicity. Furthermore, in Dr. Schallhorn's estimation, visual recovery is also faster after PRK compared with LASEK.