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 changes in the human corneal endothelium 3 and 12 months after surgery. Methods: Contact wide-field specular biomicroscopy of the central corneal endothelium was performed on 76 eyes of 61 patients (aged 20 to 39 years; mean, 29.7 years) who underwent photorefractive keratectomy for the correction of myopia ranging between -1.75 and -13.50 diopters (mean, -6.60 D). The maximum estimated central depth of the photoablation was 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) preoperatively, 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 area 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% preoperatively, 64.02%+/-10.53% after 3 months (P=.806), and 67.19%+/-9.14% after 1 year (P=.025). Conclusions: Photorefractive keratectomy caused no damage to the corneal endothelium. Postoperative improvements of the coefficient cell area variation and the percentage of hexagonal cell values may be related to corneal metabolic modifications or discontinuance of contact lens use after surgery.