Abstract
Abstract: :
Purpose: Recently, we reported that patients with ocular hypertension (OHT) have reduced outflow facility and uveoscleral outflow. Pigment dispersion syndrome (PDS) occasionally leads to OHT. The purpose of this study is to investigate aqueous humor dynamics in patients with both PDS and OHT to determine the mechanism of the intraocular pressure (IOP) elevation. Methods: Aqueous humor dynamics were compared in patients with PDS and ocular hypertension (PDS-OHT, n=19), PDS and ocular normotension (PDS-ONT, n=13) and age-matched volunteers with ocular normotension (ONT, n=19). All eye medications were discontinued for at least 3 weeks prior to measurements. IOP was measured by pneumatonometry, aqueous flow and outflow facility by fluorophotometry, episcleral venous pressure by venomanometry and anterior chamber depth by pachymetry. Uveoscleral outflow and anterior chamber volume were calculated. Statistical analyses were done by unpaired, two-tailed t-test. Results: Significant differences in the PDS-OHT versus ONT groups are as follows (values are means±SDs): increased IOP (21.0±3.4 versus 14.9±2.1 mmHg, respectively, p<.001), reduced outflow facility (0.20±0.09 versus 0.31±0.16 µl/min/mmHg, p=.01) and increased anterior chamber volume (251±47 versus 219±47 µl, p=.04). IOPs in PDS-OHT were higher than in PDS-ONT (21.0±3.4 versus 16.7±2.5, respectively, p=.001). Mean outflow facility (0.24±0.13 µl/min/mmHg) and anterior chamber volume (222±53 µl) in the PDS-ONT group fell between the other two groups, but the differences were not significant compared to either group. Uveoscleral outflow rates in the three groups were not significantly different and ranged from 1.2±0.8 to 1.4±0.7 µl/min. Conclusions: Different from patients with OHT alone, patients with pigment dispersion syndrome and ocular hypertension have increased IOP due to a reduction in outflow facility without an effect on uveoscleral outflow. Aqueous humor dynamics in patients with pigment dispersion syndrome without elevated IOP were not significantly different from healthy volunteers.
Keywords: intraocular pressure • outflow: trabecular meshwork • outflow: ciliary muscle