title: Quantification of blood-aqueous barrier breakdown after photorefractive keratectomy for myopia.
abstract: BACKGROUND
  Photorefractive keratectomy (PRK) using the excimer laser is a well-established surgical technique for correction of mild to moderate myopic refraction errors in case of spectacle or contact lens incompatibility. As it is still uncertain whether this procedure causes intraocular inflammatory 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.
  
  
  METHODS
  Aqueous flare was quantified using the laser flare-cell meter after medical pupil dilation preoperatively and on days 1, 3 and 7 as well as 1 month and 3 months following PRK with a 193-nm excimer laser (MEL 60, Aesculap-Meditec) in 37 eyes of 22 patients. The preoperative spherical equivalents were -4.4 +/- 3.1 D (range -1.5 to -8.0 D). Pre-, intra- and postoperative treatment was standardized.
  
  
  RESULTS
  Preoperatively, aqueous flare values were 3.9 +/- 0.8 photon counts/ms and showed no significant correlation with the spherical equivalent (p > 0.1). Postoperatively, aqueous flare rise was very small with flare values not significantly 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 examination.
  
  
  CONCLUSIONS
  Our results indicate that PRK in mild to moderate myopia does not cause a significant breakdown of the blood-aqueous barrier.
authors.affiliation: Augenklinik mit Poliklinik, Universität Erlangen-Nürnberg, Germany. nhung.nguyen@augen.med.uni-erlangen.de
authors.forename: N X
authors.initials: NX
authors.lastname: Nguyen
authors.forename: B
authors.initials: B
authors.lastname: Seitz
authors.forename: A
authors.initials: A
authors.lastname: Langenbucher
authors.forename: M
authors.initials: M
authors.lastname: Küchle
mesh_terms: D000328:Adult; D000869:Anterior Eye Segment / Q000098:blood supply*; D001082:Aqueous Humor / Q000166:cytology / Q000378:metabolism*; D018916:Blood-Aqueous Barrier; D002199:Capillary Permeability; D003315:Cornea / Q000601:surgery*; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007834:Lasers; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D018903:Photorefractive Keratectomy