Objective: To assess aqueous humor dynamics in pigment dispersion syndrome (PDS). Methods: Four groups of age-matched participants included 2 experimental groups with PDS (PDS with ocular hypertension [PDS-OHT], 17 eyes; PDS without ocular hypertension [PDS-ONT], 18 eyes) and 2 control groups without PDS (OHT, 18 eyes; ONT, 18 eyes). Assessments included intraocular pressure measured by pneumatonometry, episcleral venous pressure by venomanometry, aqueous flow and outflow facility by fluorophotometry, corneal thickness and anterior chamber depth by pachymetry, and uveoscleral outflow by mathematical calculation. Comparisons were made by analysis of variance and 2-tailed unpaired t tests. Results: The PDS-OHT group had higher intraocular pressures than the ONT and PDS-ONT groups (P<.001) and higher episcleral venous pressure (P=.04) and lower outflow facility (P=.01) than the ONT group. Anterior chamber volume was larger in the PDS-OHT group than in the other groups (P<.05 for all). No other comparisons between the PDS-OHT group and the other groups yielded statistically significant differences at a significance level of less than .05. Conclusions: The elevated intraocular pressure in PDS is caused by reduced outflow facility. This differs from OHT without PDS, in which reductions in uveoscleral outflow and outflow facility have been reported.
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