The Effect of Overnight Orthokeratology Lens Wear on Corneal Endothelial Cells in Adolescents

Objective: To investigate the effect of overnight orthokeratology (ortho-k) lens wear on the number and morphology of corneal endothelial cells in adolescents. Methods: This was a retrospective self-control study. Twenty adolescents with monocular myopia who had been wearing ortho-k lenses overnight for more than one year from 2015 to 2017 were included in this study at Peking University Third Hospital. Twenty eyes prescribed to wear ortho-k lenses overnight were the experimental group, and 20 contralateral eyes without treatment were the control group. The corneal endothelium was examined with specular microscopy to calculate mean endothelial cell density (ECD), percentage of hexagonal cells (HEX) and the coefficient of variation (CV) before and after wearing the lenses for 1 year. A paired t-test was used to analyze the data between the two groups. Results: There were no significant differences in baseline ECD, HEX or CV between the two groups (P>0.05). In the control group, ECD also decreased (t=2.490, P=0.022) with an annual decrease of 1.99%; HEX decreased (t=4.096, P=0.001) with an annual decline of 4.23%. There was no significant difference in CV between the two groups (P>0.05). In the experimental group, ECD showed a downward trend (t=5.802, P 0.05). Conclusions: The number and morphology of corneal endothelial cells are not significantly affected by wearing overnight ortho-k lenses for one year. Key words: orthokeratology; myopia; endothelial cell density; percentage of hexagonal cells; coefficient of variation