Neurotrophic epitheliopathy suggested as post-LASIK dry eye cause

SAN FRANCISCO — The problem of dry eye after LASIK is most likely the result of a neurotrophic epitheliopathy induced by the severing of corneal nerves when the flap is made, rather than diminished tear production. This is the conclusion of a study by Steven E. Wilson, MD, as reported in the June issue of Ophthalmology.

In this retrospective case control study, individual eyes of 19 patients with moderate to severe erosions of the corneal epithelium at 1 to 3 months following LASIK were compared to eyes of 19 patients who did not develop epithelial erosions on the corneal flap. No patients who had significant signs of dry eye prior to surgery were included in the study.

The comparison of the two groups of patients revealed no difference in tear production at 1, 3, or 6 months and no significant difference in corneal irregularity or refractive correction, though some patients had a temporary decrease in visual acuity.

What was found, according to Dr. Wilson, of the department of ophthalmology at the University of Washington in Seattle, was that "the signs and symptoms of LASIK-induced neurotrophic epitheliopathy (LNE) tend to resolve at approximately 6 months after surgery." Other studies have shown that on average this is when corneal nerves complete regeneration into the flap.

Dr. Wilson pointed out that approximately 4% of patients who have LASIK develop the LNE-associated epithelial erosions, which "may interfere with vision in some patients." Patients who have dry eye disease prior to LASIK are more likely to develop LNE and have more severe outcomes. He also said "it is unknown whether LNE is attributable to diminished neurotrophic factors released from the nerves or some other factor such as a decrease in the frequency of blinking." He called for further study "to clarify the mechanism and the association with the return in corneal sensation."

Dr. Wilson emphasized the importance of warning LNE-affected patients that "LASIK enhancement will likely be associated with a return of the symptoms and signs of LASIK-induced neurotrophic epitheliopathy." He advised in these cases that "enhancement be performed in one eye at a time, separated by at least 6 months so the patient's visual function is maintained."

A report by Rosan Y. Choi, MD, and Dr. Wilson describing their experience with LNE appeared in the January 1, 2001, issue of Ocular Surgery News.