Endothelial morphologic features and function after long-term extended wear of contact lenses

We performed anterior segment fluorophotometry and endothelial cell photography on 11 subjects who had used extended-wear contact lenses for at least two years. The lenses had been removed for cleaning at intervals of one to four weeks. Forty subjects of similar age who did not wear contact lenses served as a control group. The coefficient of variation of cell size was increased in the contact lens group compared with the control group; no significant difference in mean endothelial cell size was found. The percentage of seven-sided cells making up the endothelial cell mosaic was increased in the contact lens group compared with the control group (15% vs 12%, respectively). No difference in corneal clarity, central corneal thickness, endothelial permeability to fluorescein, or rate of flow of aqueous humor was found between the groups. There was a significant correlation between duration of lens wear and mean endothelial cell size. Extended-wear contact lens usage induces morphological changes in the corneal endothelium; these changes may progress as the duration of lens wear increases. We detected no functional impairment, however.