Swelling and loss of photoreceptors in chronic human and experimental glaucomas

Objective: To determine whether outer retinal changes occur in chronic, pre sumed primary open-angle glaucoma (POAG). Methods: The outer retinas from 128 human eyes with a diagnosis of chronic glaucoma (presumably POAG in most cases) and 90 control eyes were examined histologically by 3 masked observers for photoreceptor swelling and loss. R etinas from 9 rhesus monkeys with glaucoma induced experimentally by laser trabecular destruction were compared with 7 fellow (control) eyes. The mean pressure elevations in the eyes with laser trabecular destruction ranged f rom 26.6 to 53.6 mm Hg with durations varying from 7 to 33 weeks. Results: Swelling of the red- and green-sensitive cones was observed in a s tatistically significantly greater proportion of human eyes with presumed P OAG compared with the control eyes. Patchy loss of red/green cones and rods was also found in some of the glaucomatous retinas. In a subset of the hum an eyes with end-stage disease, cone swelling was a variable finding. Altho ugh no photoreceptor loss was found in the 9 monkey eyes with experimental glaucoma, 8 had swelling of their red/green cones that was remarkably simil ar to that seen in the human eyes. Swelling was not present in any of the c ontrol monkey eyes. Conclusions: The photoreceptors are affected by chronically elevated intrao cular pressure. Clinical Relevance: These findings may explain some of the abnormalities of color vision and the electrophysiological effects that hav e been observed in patients with POAG.