Abstract
Abstract: :
Purpose: To determine the histological safety of topical latanoprost as well as to evaluate changes in melanocytes associated with increased iris pigmentation, with electron micrographs used to examine the ultrastructure of the iris and to find any possible association between the duration of latanoprost therapy and melanin granules of the iris surface, iris stroma, and pigment epithelium. Methods: Nine patients requiring filtering surgery were recruited. After written informed consent was obtained from each patient, a peripheral iridectomy specimen was collected during surgery. Patients had been treated with topical latanoprost for 16.9±12.7 months (0–30 months). Electron micrographs were taken of the iris surface, iris stroma and pigment epithelium, to be used for: 1) evaluation of cells and extraceller matrices; 2) counting of melanin granules; and 3) calculation of area ratio of melamine granules to melanocyte in percent, with "analySIS" (soft Imaging system, Germany). Results: No structural changes were observed in the cells and extraceller matrices. Significant correlations were found between the number of melanin granules and the duration of latanoprost therapy both on the iris surface (p=0.0247) and in the iris stroma (p=0.0003). In contrast, a significant correlation was found only on the iris surface between the percent of melanin granules to melanocytes and the duration of latanoprost therapy (p=0.021). Conclusions: Topical latanoprost therapy did not produce any ultrastructural change in iris cells. Latanoprost caused iris pigmentation by increasing the percent of melanin granules to melanocyte of the iris surface and the number of melanin granules of the iris surface and stroma.
Keywords: drug toxicity/drug effects • iris • microscopy: electron microscopy