Effect of pilocarpine on anterior chamber angles

Pilocarpine is widely used in the treatment of glaucoma, especially for the acute form of angle-closure glaucoma. Previous studies have shown that pilocarpine decreases central anterior chamber depth. In the present study, a quantitative measurement method, applying Scheimpflug photography, was used to report whether pilocarpine also affected the anterior chamber angles. Twenty-nine normal Chinese subjects, 17 female and 12 male with an age range from 11 to 63 years old, were enrolled. One eye of each subject was treated with one drop of 2% pilocarpine. Photographs of each of four quadrants were taken prior to, and after, pilocarpine treatment in both eyes, using a rotating slit-lamp video camera based on the Scheimpflug principle. The slit beams were set at 0 degrees and 90 degrees. The eyes which did not receive pilocarpine treatment served as control. The angles of the four quadrants were calculated for both eyes both prior to, and after, pilocarpine treatment, and results were compared by Student's paired t-test. The comparison of angles between the eyes prior to, and after, pilocarpine treatment indicated that there is a significant narrowing of angles in all quadrants. The complex factors involved in the change of anterior chamber angle are reviewed in the light of muscarinic action of pilocarpine.