THE CORNEAL ENDOTHELIUM AFTER MYOPIC EXCIMER-LASER PHOTOREFRACTIVE KERATECTOMY

Objective: To investigate whether 193-nm excimer laser photorefractive keratectomy for the correction of myopia can determine in vivo change s in the human corneal endothelium 3 and 12 months after surgery. Meth ods: Contact wide-field specular biomicroscopy of the central corneal endothelium was performed on 76 eyes of 61 patients (aged 20 to 39 yea rs; mean, 29.7 years) who underwent photorefractive keratectomy for th e correction of myopia ranging between -1.75 and -13.50 diopters (mean , -6.60 D). The maximum estimated central depth of the photoablation w as 113 mu m. Photomicrographs of the endothelium taken before surgery were processed by means of computer-assisted morphometric analysis and compared with those obtained 3 and 12 months after surgery. Results: The mean (+/-SD) cell density was 2657+/-298 cells/mm(2) preoperativel y, 2672+/-286 cels/mm(2) after 3 months (P=.670), and 2656+/-289 cells /mm(2) after 1 year (P=.982). The mean (+/-SD) coefficient of cell are a variation was 30.27%+/-5.99% preoperatively, 28.25%+/-5.21%;, after 3 months (P=.032), and 26.35%+/-5.29% after 1 year (P=.001). The mean (+/-SD) percentage of hexagonal cells was 63.82%+/-9.94% preoperativel y, 64.02%+/-10.53% after 3 months (P=.806), and 67.19%+/-9.14% after 1 year (P=.025). Conclusions: Photorefractive keratectomy caused no dam age to the corneal endothelium. Postoperative improvements of the coef ficient cell area variation and the percentage of hexagonal cell value s may be related to corneal metabolic modifications or discontinuance of contact lens use after surgery.