Iris transillumination defects in the pigment dispersion syndrome as detected with infrared videography: a comparison between a group of blacks and a group of nonblacks.

Abstract

Infrared image analysis has been reported to be the most sensitive method to detect iris transillumination defects (ITDs) associated with the pigment dispersion syndrome (PDS). Although a common sign of PDS in patients with lighter irides, ITDs that are demonstrated with standard slit lamp examination are frequently absent in blacks with the disease. This absence may lead to confusion in diagnosis; therefore improved methods of evaluation could be beneficial. Although infrared image analysis has been investigated in nonblacks, it has not been applied to a group of blacks with the condition. Six blacks (11 eyes, all irides brown) with PDS and eight nonblacks (15 eyes, 10 blue irides, 5 brown irides) with PDS underwent analysis. ITDs were searched for with traditional slit lamp examination and with infrared videography. Among the blacks, 2 of 11 eyes (18%) showed ITDs via infrared analysis, a frequency that was significantly lower (p < 0.001) than the frequency exhibited among the nonblacks (100%) when examined with the same technique. Standard slit lamp examination also showed a significantly lower frequency of ITDs among the blacks compared to the nonblacks (p < 0.001). Infrared videography detected ITDs at least one grade higher in 1 of 11 eyes (9%) among the black group and in 7 of the 15 eyes (47%) among the nonblacks. Using the Wilcoxon signed ranks test, the difference in the ability of infrared videography to detect and rank the iris defects in the nonblack PDS group was significantly greater when compared to standard slit lamp examination (p = 0.011), but infrared analysis did not increase detection or change the mean ranking of those in the black group (p = 0.317). In this group of patients, infrared videography did not significantly improve the detection and visibility of ITDs in blacks, as it did in the nonblacks. The frequency that ITDs were detected with standard slit lamp examination and with infrared videography was significantly greater in the group of nonblacks compared to the blacks who exhibited PDS.