LOCATION OF THE IRIS INSERTION IN PIGMENT DISPERSION SYNDROME

Purpose: To evaluate the position of the iris insertion into the cilia ry body in persons with pigment dispersion syndrome (PDS) and control subjects. Methods: Ultrasound biomicroscopy was performed on 19 eyes w ith PDS and on 21 eyes of control subjects. A radial, perpendicular im age in the temporal meridian detailing Schwalbe line (SL), scleral spu r (SS), and iris root insertion (IR) was obtained for each eye by a si ngle examiner. The distances between these structures then was measure d. Results: There were no differences between the groups in refractive error (mean +/- standard error, -2.8 +/- 0.7 diopters for PDS eyes ve rsus -2.2 +/- 0.6 for control subjects) (P = 0.46), sex distribution ( P = 0.49), and trabecular meshwork height (SL to SS) (0.63 +/- 0.03 mm [PDS eyes] versus 0.59 +/- 0.03 [control eyes]; P = 0.24). The SS-to- IR distance was significantly greater in PDS eyes (0.40 +/- 0.04 mm) t han in control eyes (0.28 +/- 0.04 mm) (P = 0.01) as was the overall d istance from SL to IR (0.98 +/- 0.04 mm versus 0.81 +/- 0.04 mm) (P = 0.003). Conclusion: The insertion of the iris into the ciliary body is more posterior in PDS eyes than in control eyes. This anatomic variat ion places the iris pigment epithelium proximal to the zonular apparat us and may increase the likelihood of iridozonular contact and zonular pigment dispersion.