Influence of Overnight Orthokeratology on Corneal Endothelium

PURPOSE: To evaluate the influence of overnight orthokeratology on the corneal endothelium. METHODS: Fifty-two eyes of 31 patients undergoing overnight orthokeratology for myopia were examined. They wore the lens every night and were followed up for at least 1 year. The corneal endothelium was examined with specular microscopy to calculate mean endothelial cell density, coefficient of variation of cell area, and percentage of hexagonal cells. Data obtained at 1-year follow-up examinations were compared with those at the baseline examinations using a paired t test. RESULTS: Orthokeratology significantly reduced manifest refraction from -2.32 +/- 1.18 D (mean +/- standard deviation) to -0.16 +/- 0.33 D (P < 0.0001) and improved uncorrected visual acuity from 0.77 +/- 0.29 to -0.07 +/- 0.10 logMAR (P < 0.0001). The endothelial cell density did not change significantly (2879 +/- 231 cells/mm before and 2864 +/- 260 cells/mm after treatment, P = 0.252). The coefficient of variation of cell area was 22.3 +/- 2.7 at baseline and 22.1 +/- 2.4 at 1-year posttreatment, which did not change significantly (P = 0.537). The percentage of hexagonal cells was 72.8 +/- 10.2% pretreatment and 72.5 +/- 10.9% posttreatment (P = 0.800). CONCLUSIONS: Overnight orthokeratology for 1 year did not influence the density or morphology of corneal endothelial cells.