Epithelial ingrowth seen increasing in older population

Epithelial ingrowth, a common complication after LASIK enhancement procedures, may be more frequent with increasing patient age and as hyperopic ablations are more common in older patients. This may explain previous findings that epithelial ingrowth occurs more often in hyperopic ablations.

Epithelial ingrowth, a common complication after LASIK enhancement procedures, may be more frequent with increasing patient age and as hyperopic ablations are more common in older patients. This may explain previous findings that epithelial ingrowth occurs more often in hyperopic ablations.

Colin C.K. Chan, MD, FRANZCO, from The Eye Institute, Sydney, Australia, and Brian Boxer Wachler, MD, director of the Boxer Wachler Vision Institute, Los Angeles, found that application of a contact lens increases the clinical incidence of epithelial ingrowth after LASIK re-treatment and appears to have no benefit. Use of a contact lens after LASIK re-treatments, a common treatment practice after the procedure, actually may cause rather than prevent epithelial ingrowth.

“The incidence rates of epithelial ingrowth after LASIK enhancement procedures in the literature range from 0% to 55%, and there may be such a wide variation because there is no common standard of description,” Dr. Chan explained.

“Numerous methods have been tried to prevent the occurrence of epithelial ingrowth, such as contact lens application overnight, suturing the flap, alcohol, and mitomycin-C, but none has been shown to prevent epithelial ingrowth fully,” Dr. Chan said. “That is likely because we don’t understand why epithelial ingrowth occurs. The most common hypothesis is that there is trauma to the flap edge after lifting that results in abnormal epithelial behavior and subsequent ingrowth under the flap. Another hypothesis is that epithelial ingrowth is more common in hyperopic ablations because peripheral laser pulses in the hyperopic zone result in direct irritation of the epithelial cells.”

The investigators looked at 30 consecutive eyes in three groups that underwent re-treatments after LASIK. The first group of 10 eyes was the forceps lift group, which was treated with what had been the standard method, using a Hunkler hook to run under the flap edge for 1 to 2 mm followed by tearing back of the flap with a forceps. The second group of 10 eyes had a bandage contact lens placed at the end of the procedure that was removed the next day. The third group of 10 eyes had no bandage contact lens placed and instead of a forceps to tear the edge of the flap, the investigators used a Pinelli spatula to delineate the entire flap instead of just 1 to 2 mm before lifting, Dr. Chan explained.

The investigators defined epithelial ingrowth as greater than 1.5 mm of epithelial ingrowth from the edge of the flap with visual symptoms or topographic changes, according to Dr. Chan. All patients underwent a LASIK re-treatment procedure with an excimer laser system (LADARVision, Alcon Laboratories).

“The most striking finding was in the contact lens group, in which there was a sudden surge of epithelial ingrowth in four of the 10 patients (40%),” Dr. Chan reported. “While this was a small study, there was a trend toward significance of p = 0.11. This finding was contrary to what we thought was going to happen, because contact lenses have been used to prevent epithelial ingrowth.”

He speculated that the epithelial ingrowth might have resulted from irritation caused by an ill-fitting contact lens due to the change in the shape of the cornea after LASIK ablation or because the lens was removed the day after the re-treatment, which might have resulted in mechanical trauma.

In the spatula group, only one of the 10 patients (10%) developed epithelial ingrowth, he said.

“That case of epithelial ingrowth was a borderline case at best. The result in this group may have been due to the shape of the Pinelli spatula. The spatula has a curved end that fits nicely under the flap edge,” Dr. Chan said. “The resulting effect is a nice, clean flap edge compared with the results when a Hunkler hook is used, because that instrument causes tearing of the edge, creation of epithelial tags, and presumably more epithelial trauma.”

Dr. Chan also found a difference in the ages of the patients who developed epithelial ingrowth.

“When we compared the ages in the study, those who developed epithelial ingrowth were older patients (mean age, 53 years) compared with those who did not develop epithelial ingrowth, who had a mean age of 44 years [p = 0.07],” he said.

A significant (p = 0.04) finding was that the development of epithelial ingrowth was not related to whether the ablation was to treat hyperopia or myopia, as previously thought.

“That is counterintuitive, because we had thought hyperopic ablations would irritate the epithelium more than a myopic ablation,” Dr. Chan said. “However, they did not in this case.”

Considering the trend for increased development of epithelial ingrowth with increasing age the development of epithelial ingrowth was not related to the preoperative spherical equivalent, he said.

“We hypothesized that this is due to the fact that the increase in hyperopic ablations is due to the age factor,” Dr. Chan said. “With increasing age, there is more loose epithelium, more epithelial trauma, and more anterior basement dystrophy. With aging, there are more hyperopic ablations and more hyperopic re-treatments. Perhaps those two factors compound each other and lead to the increased incidence in hyperopic ablations.

“The area deserves further prospective study to delineate those findings,” Dr. Chan concluded. “In the current series of eyes, we found that using a contact lens did not help prevent epithelial ingrowth, which is counter to the current thinking and what is reported in the literature. Epithelial ingrowth occurred more frequently in older patients and was not related to the type of ablation.”OT