Long-Term Changes in Corneal Endothelial Morphology After Discontinuation of Low Gas-Permeable Contact Lens Wear

Abstract

Low gas-permeable contact lens wear of polymethyl methacrylate or hydroxyethyl methacrylate material is known to cause morphologic abnormalities in the corneal endothelial cell layer. These lenses were widely prescribed and successfully worn until their use was actively discouraged in the late 1980s and early 1990s. This study was designed to investigate whether discontinuation of low gas-permeable contact lens wear leads to an improvement of corneal endothelial cell morphology. At the time of discontinuation and at least 5 years after discontinuation of low gas-permeable contact lens wear, noncontact specular photographs of the central corneal endothelium were made in 66 patients (14 male and 52 female, mean age 37.7 +/- 8.4, range 24.6-69.0). By computer analysis of endothelial photographs, parameters for polymegethism and pleomorphism were calculated, as well as cell density. Mean follow-up time between photographs was 6.8 years (SD 1.1). Sixty-one patients were refitted with rigid high gas-permeable contact lenses or high-water-content soft lenses, and 5 patients switched to spectacle wear. A small but significant recovery of the corneal endothelial cell morphology was found for the mean coefficient of variation of cell area, from 37.5 to 35.7 (P = 0.022), and for the coefficient of variation of the number of sides, from 13.1 to 12.4 (P = 0.004). The mean percentage of hexagonal cells increased from 54.2 to 56.2 (P = 0.013). Although the corneal endothelial cell morphology improved significantly on cessation of LGP contact lens wear, the values did not return to levels observed in normal, non-contact lens wearing individuals. During follow-up, the mean endothelial cell density decreased significantly (P = 0.001) from 2994 to 2890 (a 3.5% cell loss in 6.8 years), which is similar to the known normal age-related cell loss of 0.6% per year in non-contact lens wearing healthy individuals. Endothelial polymegethism and pleomorphism caused by PMMA or HEMA contact lens wear is partly reversible.