Blood vessels of the glaucomatous optic disc in experimental primate and human eyes.

Experimental chronic glaucoma was produced in primate eyes and quantitative measurements were made of the capillary area in the optic nerve head. The percent of the nerve head occupied by capillaries remained normal despite considerable loss of disc tissue as glaucomatous excavation proceeded. This finding, identical to that in simple optic atrophy, suggests that the nerve head can maintain a stable capillary to tissue ratio despite substantial tissue loss. Further observations on human glaucoma eyes confirmed that there is not selectively greater loss of capillary volume out of proportion to the loss of neural tissue of the optic nerve head. Fluorescein angiography of primate and human glaucoma eyes showed that a change in the appearance of disc vessels occurred most frequently when there was little or no remaining neural or vascular tissue anterior to the scleral lamina cribrosa.