Ultrasound biomicroscopy in asymmetric pigment dispersion syndrome and pigmentary glaucoma

Objective: To identify differences in anterior chamber anatomy among patients with asymmetric pigment dispersion syndrome and no other discernible cause for the asymmetry. Methods: Ultrasound biomicroscopy and A-scan biometry were performed on both eyes of 13 patients with asymmetric pigment dispersion syndrome without a known cause for asymmetric involvement. A radial perpendicular image in the horizontal temporal meridian detailing the scleral spur, angle anatomy, and iris configuration was obtained for each eye by 2 examiners. Results: There were no differences in lens thickness (P = .33), refractive error (P = .84), or axial length (P = .99) between more and less affected eyes. However, the mean ± SD iris concavity (P<.001), iris-lens contact distance (P = .02), and distance from the scleral spur to the iris insertion (0.42 ± 0.11 vs 0.29 ± 0.06 mm) (P = .002) were greater in the more affected eye of each patient. Conclusion: A more posterior iris insertion predisposes to the phenotypic expression of pigment dispersion syndrome.