Purpose: To evaluate the 3- to 4-year effects of the Implantable Contact Lens (ICL) on the corneal endothelium.
Setting: Multicenter study.
Methods: Noncontact specular microscopy was performed as a subgroup study in a Phase III U.S. Food and Drug Administration clinical trial. Endothelial cell images were collected in the central region of the cornea before surgery and 3, 12, 24, and 36 months after surgery, with a few at 48 months. The images were recorded and analyzed later by a central reading center. The cell density, coefficient of variation, and percentage of hexagonal cells were determined.
Results: The cumulative endothelial cell loss was between 8.4% and 8.9% over the first 3 years and between 8.4% and 9.5% over the first 4 years depending on the method of calculation. The cell loss between baseline and 3 months was 2.1%; 3 months and 1 year, 0.9%; 1 year and 2 years, 2.3%; 2 years and 3 years, 3.2%; and 3 years and 4 years, -0.1%. The coefficient of variation decreased over the course of the study, and the proportion of cases with hexagonal cells increased slightly.
Conclusions: The cell loss between 1 year and 3 years in the absence of an increase in the coefficient of variation and/or a decrease in the percentage of hexagonal cells is most readily explained by prolonged corneal remodeling following the surgical procedure rather than ongoing cell loss. The cell loss observed between 3 years and 4 years (0.1% gain) was negligible. Regardless of the cause of the change in endothelial cell density over the first 3 years, the available 4-year data suggest there was no ongoing chronic loss.