Central and peripheral endothelial cell changes after excimer laser photorefractive keratectomy for myopia

S. D. Trocme, K. A. Mack, K. S. Gill, D. H. Gold, B. A. Milstein and W. M. Bourne
Department of Ophthalmology and Visual Sciences, School of Medicine, University of Texas Medical Branch, Galveston, USA.

OBJECTIVE: To investigate changes in the human corneal endothelium after photorefractive keratectomy for treatment of myopia. DESIGN: Specular microscopy of the central, paracentral, and peripheral zones of the corneas of 14 patients (12 of whom were previous contact lens wearers) was performed preoperatively and at 1, 2, 3, 6, and 12 months after photorefractive keratectomy. The corneal endothelial cell density, coefficient of variation (CV) of the endothelial cell area, and percentage of hexagonal cells were assessed at each examination. RESULTS: The central endothelial cell density was increased by 7% during the first 3 postoperative months (P < .05). In contrast, the peripheral cell density declined steadily by 6.9% during the first year (P < .01). The CV of the cell area was decreased in all 3 zones, whereas the percentage of hexagonal cells was increased in the central and paracentral zones (P < .05). CONCLUSIONS: We observed statistically significant changes in the central and peripheral endothelial cell densities and morphological features that could have resulted from photorefractive keratectomy; however, these changes also may have been explained by the discontinuation of contact lens wear. If such changes are contact lens-related, they could mask the effects of laser-induced damage to the central zone of the endothelium.