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Clinical data and the common embryological origin of the pigment epithelium of the iris and retinal pigment epithelium suggest that the latter may be involved in the pigment dispersion syndrome (PDS). In our study functional changes of the retinal pigment epithelium were evaluated by electro-oculography in 10 PDS patients, 10 patients with chronic open-angle glaucoma (COAG) and 10 normal subjects. The mean dark-trough latency and Arden ratio for the PDS group were significantly lower than those of the COAG and control groups. Analysis of the Arden ratios based on the Kruskall-Wallis test revealed that 30% of the PDS values were subnormal with respect to the control group mean –1 SD. These results indicate primary involvement of the retinal pigment epithelium in PDS.

The purpose of this study was to compare the variability of the amplitude ratios and latencies of the electro-oculogram (EOG) light peak (LP) in three different recording conditions: Arden ratio (dark trough (DT): 12 min), modified Arden ratio (DT: 15 min) and light peak/dark baseline ratio (LP/BL: 35 min of dark adaptation). Additionally, EOGs from eyes with dilated and undilated pupils were recorded. The light intensity stimulating the eyes with dilated pupils was attenuated 1 log unit. The EOG amplitude ratios displayed no significant difference between the three conditions tested. The comparison of implicit times (time from onset of light exposure to LP) revealed significantly (p0.001) shorter values when the recording of the LP was preceded by a dark adaptation of 35 min. The broadening of the curves in DT/LP recordings might be caused by a superposition of a residual dark oscillation on the LP. The recordings from eyes with dilated pupils--stimulated with 1 log unit lower intensity--revealed lower amplitude ratios than the recordings from eyes with undilated pupils.