THE EFFECT OF PILOCARPINE ON THE GLAUCOMATOUS VISUAL-FIELD

Patients with chronic open angle glaucoma are traditionally managed by medical therapy during the early stages of the disease. Pilocarpine i s a well established topical agent, but suffers troublesome sequelae, the most apparent of which is pupillary constriction. This study asses ses the effect of miosis (produced by one drop of 2% pilocarpine) on t he static threshold perimetry of 20 subjects with chronic open angle g laucoma and documented visual field loss, using the 30-2 program of th e Humphrey field analyser. Following miosis, the Statpac mean defect d eteriorated by an average of -1.49 dB compared with baseline (p=0.004) . This dB deterioration is twice that reported in studies on younger n ormal subjects following miosis. The decrease in mean defect showed a positive correlation with the degree of pupillary constriction, the co rrelation being greater in those eyes with a miosed pupil diameter of 2 mm or less. There was no significant decrease in the other Statpac g lobal indices following miosis. A parallel study using the fellow eye of the same glaucoma patients showed a high degree of intertest variab ility, but no significant learning or fatigue effect. We conclude that pilocarpine-induced miosis causes a significant deterioration in visu al field in a population of patients with chronic open angle glaucoma: this factor should be considered when choosing therapy for glaucoma p articularly in cases where field loss approaches the permitted legal m inimum for driving.