Pigment release.

Guttae phenylephrine 10% produced a significant decrease in intraocular pressure and increase in facility of outflow in eyes with untreated ocular hypertension. If at the same time pigment was released into the aqueous, the pressure and outflow effect was nullified. Guttae pilocarpine 2% also reduced pressure and increased outflow, but if phenylephrine was added to the pilocarpine 2 responses appeared. If no pigment was released, pressure decreased and outflow increased; if pigment was released, there was no significant change in either. An identical response was shown by eyes with treated open-angle glaucoma. In eyes with treated exfoliation glaucoma pilocarpine and phenylephrine combined produced a significant increase in pressure and decrease in outflow because of pigment release. Finally, 18 eyes are described in which pigment release produced a mean increase in intraocular pressure of 14 mmHg. An acute release of pigment has an outflow-blocking effect that can be readily demonstrated. It provides an explanation for some of the paradoxical responses that occur after the instillation of autonomic drugs. It also provides a sufficient explanation for glaucoma associated with pigment dispersion.