Ocular anterior segment disease in northern fur seals

Eyes of 1,716 wild northern fur seals (Callorhinus ursinus; 1,501 subadults and 215 adults) were examined for the prevalence of ocular anterior segment disease; 4.6% of the seals had clinically recognizable eye lesions. Six seals had bilateral eye lesions. Corneal scars were the most frequently observed lesion, followed by prominent lens sutures, cataracts, and iris depigmentations. Corneal edema, active corneal ulceration, or inflammation was not observed. Examination of normal corneas indicated an epithelial structure similar to that of the California sea lion, with 11 to 14 layers of nucleated superficial stratified squamous cells that lacked keratohyaline granules. The seal corneal endothelium had less hexagonality than do human corneal endothelial cells, with mean endothelial cell areas of 331 to 396 micron2, similar to that found in primates.