The corneal endothelium after myopic excimer laser photorefractive keratectomy
F. Carones, R. Brancato, E. Venturi and A. Morico
Department of Ophthalmology and Visual Sciences, San Raffaele Hospital, University of Milan, Italy.
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 49 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
microns. 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/mm2 preoperatively, 2672 +/- 286
cells/mm2 after 3 months (P = .670), and 2656 +/- 289 cells/mm2 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.
