Ahram Mineral Water-induced Sulfate Keratopathy: Histopathologic, Electron Microscopic and Confocal Scan Features

To characterize the histopathologic, electron microscopic and confocal scan features of Ahram mineral water (AMW)-induced keratopathy in cadaver corneas. Seven cadaver globes were examined, five of which were exposed to AMW from the corneal side for different durations (30 seconds, 3, 15, 30, and 60 minutes) and the other two were considered as controls. After performing confocal scan on each cornea, the corneo-scleral rim was excised and sent for histopathologic evaluation. Scanning electron microscopic (SEM) and transmission electron microscopic (TEM) examinations were performed on the cornea exposed to AMW for 60 minutes. Pending the time of exposure, confocal scan features varied from intra-epithelial high contrast deposits to sub-epithelial bulla formation. Histopathologic features ranged from diffuse intra-cytoplasmic sulfur deposits to sub-epithelial bulla formation. SEM disclosed rather diffuse irregular bright deposits of high sulfur content over the surface epithelium together with focal cellular destruction and micro-hole formation in the case with 60-minute exposure. On TEM, bulky electron lucent deposits were found underneath the basal epithelial cells and between their basement membrane and Bowman's layer. Confocal scan of the control corneas disclosed non-specific anterior stromal haze and Descemet's folds with no evidence of intraepithelial deposits. No intra-epithelial deposits were found on the histopathologic examination of the control corneas. Ahram mineral water induces sulfate keratopathy predominantly involving the anterior cornea with various histopathologic, confocal microscopic and electron microscopic features even with short-time exposure.