Pigment dispersion syndrome (PDS)describes an eye condition in which the pigmented cells on the posterior surface of the iris are lost and washed away by the aqeous humor to be deposited on the outflow channels of the eye. This may be asymptomatic or cause elevated pressure and occasionally glaucoma. Since the pigmented cells give rise to the dilator muscle of the iris, the hypothesis to be tested is that patients with PDS will have abnormal pupillary dilation as compared to normal individuals. Pupilography is performed to determine the speed and amount of dilation after a light flash. Assessment of involvement of the dilator muscle may assist in establishing an etiology of the PDS
