One model of outflow damage.

The intraocular pressure, facilities of outflow, and Po/C ratios of 3 groups of eyes were compared. Group 1 consisted of 20 eyes at risk to the development of acute closed-angle glaucoma that had been treated with prophylactic pilocarpine for at least 8 years. Group 2 consisted of 20 eyes at risk that had received no treatment and had been followed up for at least 4 years. Group 3 comprised 20 eyes in which there was no evidence of glaucoma. There were highly significant differences between the 3 groups. The 60 eyes were then provoked with pilocarpine and phenylephrine; 90% of Group 1, 75% of Group 2, and none of Group 3 developed significant gonioscopic angle closure. These results suggest that asymptomatic partial angle closure was the cause of the observed changes and provide a naturally occurring model of one mechanism that can produce outflow damage without clinical symptoms.