Corneal endothelial density and morphology in long-term soft contact lens users in Japan: a retrospective cross-sectional study of 17,732 eyes.

Purpose: There is a lack of long-term and large-scale studies on the adverse effects of soft contact lenses (SCLs) on the corneal endothelia of Asian populations. Here, we aimed to examine the effects of long-term SCL use on corneal endothelial density and morphology.

Materials and methods: This retrospective study involved consecutive patients at the Miyata Eye Hospital (Miyazaki, Japan), who had used SCLs for more than 1 year. Patients with ophthalmological disorders without refractive errors were excluded. The period of SCL use, SCL type, corneal endothelial cell density (ECD), appearance rate of hexagonal cells (HEX), and coefficient of variation of cells (CV) were analyzed.

Results: In total, 17,732 eyes of 8866 patients were included in the analysis (age, 26.0 ± 8.8 years). The mean period of SCL use was 6.3 ± 5.4 years. Multivariate regression analysis revealed that ECD and HEX were significantly negatively correlated with the period of SCL use, age, and sex (p < 0.001 for all). The CV was significantly positively correlated with the period of use (p < 0.001), sex (p = 0.002), and age (p < 0.001).

Conclusions: Corneal ECD, HEX, and CV were significantly associated with the period of SCL use in long-term users. It is essential to regularly check the corneal endothelium in patients with a history of long-term SCL use.