Does Beta-ray Emitting Therapy of Ciliary Body Tumors Decrease Central Corneal Endothelial Cell Density?

Abstract

To evaluate the effect of plaque radiation therapy using beta-radioactive isotope for anterior segment tumors on the density and morphology of endothelial cells. Endothelial cell density (ECD) and morphometry in 15 eyes of 15 patients with ciliary body tumor was examined prior to and 6 months after radiation therapy. After irradiation, central ECD values were also compared with peripheral (2.0 mm from limbus) ECD values measured around the plaque. The ECD, average cell area, coefficient of variation of cell area, and pachymetry measurements were conducted with contact specular microscopy. The mean corrected ECD values prior to irradiation were 2147 ± 128 cells/mm2 and 2050 ± 108 cells/mm2 after the radiation therapy. After irradiation, the mean peripheral ECD values were 2056 ± 101 cells/mm2. A significant decrease in ECD values was observed after radiation (p = 0.007). Peripheral ECD values measured around the plaque showed no significant difference (p = 0.86) as compared to central ECD values. According to our measurements, plaque therapy for tumors in the anterior segment decreases ECD significantly, but not highly, even in case of plaques containing beta-radiation isotope, and the plaques are not placed direct on the cornea surface. The decreased ECD causes no changes in corneal thickness or transparency, but it may have an influence on a subsequent cataract surgery, which generates further endothelial loss.