Pilocarpine

High resolution ultrasonic biometry was performed on 21 normal eyes of volunteers (18 to 30 years old) prior to and at 15-minute intervals after topical instillation of pilocarpine 2%. Pilocarpine has a measurable effect on the anterior chamber and lens thickness within 15 minutes, is maximal 45 to 60 minutes after instillation, and virtually gone after 100 minutes. Every eye measured demonstrated an axial thickening of the lens (average 0.32 mm), and narrowing of the anterior chamber (average 0.29 mm). In addition to axial thickening of the lens, there was a forward translational movement of the lens with pilocarpine-induced accommodative spasm. Pilocarpine-induced accommodation and voluntary accommodation produce similar changes in the anterior chamber and lens surfaces.