Quantification of blood-aqueous barrier breakdown after photorefractive keratectomy for myopia

Background: Photorefractive keratectomy (PRK) using the excimer laser is a well-established surgical technique for correction of mild to moderate myop ic refraction errors in case of spectacle or contact lens incompatibility. As it is still uncertain whether this procedure causes intraocular inflamma tory changes, it was the purpose of this study to quantify breakdown of the blood-aqueous barrier following PRK and to look for possible correlations with clinical parameters. Patients and methods: Aqueous flare was quantifie d using the laser flare-cell meter after medical pupil dilation preoperativ ely and on days 1, 3 and 7 as well as 1 month and 3 months following PRK wi th a 193-nm excimer laser (MEL 60, Aesculap-Meditec) in 37 eyes of 22 patie nts. The preoperative spherical equivalents were -4.4+/-3.1 D (range -1.5 t o -8.0 D). Pre-, intra- and postoperative treatment was standardized, Resul ts: Preoperatively, aqueous flare values were 3.9+/-0.8 photon counts/ms an d showed no significant correlation with the spherical equivalent (p>0.1). Postoperatively, aqueous flare rise was very small with flare values not si gnificantly higher than preoperative values. All postoperative flare values were below the normal limit( <8.0 photon counts/ms). Flare was highest on day 3 after PRK surgery. There was no statistically significant correlation between aqueous flare and depth of stromal ablation. The number of aqueous "cells" did not increase following PRK at any postoperative follow-up exam ination, Conclusion: Our results indicate that PRK in mild to moderate myop ia does not cause a significant breakdown of the blood-aqueous barrier.