Aqueous Humor Dynamics in Uveitic Eyes

Abstract

To investigate aqueous humor dynamics in uveitic eyes. Cross-sectional study. Patients with recurrent (≥3 attacks) anterior uveitis (now quiescent) and being treated for glaucoma or ocular hypertension (OHT) (Group 1), previous recurrent anterior uveitis (≥3 attacks) without glaucoma or OHT (Group 2), and normal subjects with no ocular problems and IOP < 21mm Hg at screening (control group; Group 3). Patients had one-off measurements. Group 1 patients who were on antihypertensives were washed out for a 4-week period, prior to their study measurements. Main outcome measures were tonographic outflow facility, aqueous humor flow rate, and uveoscleral outflow. One hundred and one patients were screened between February 2014 and February 2017. Nine patients did not meet the inclusion criteria. Groups 1 and 3 each included 30 patients, and Group 2 included 32 patients. The mean intraocular pressure was higher in Group 1 compared to the others (25 ± 10.2mm Hg in Group 1 vs 16 ± 2.7mm Hg in Group 2 vs 16 ±2.2mm Hg in Group 3, P < .001). The tonographic outflow facility was lower in Group 1 compared to the others (0.18 ± 0.1μL/min/mm Hg in Group 1 vs 0.25 ± 0.1μL/min/mm Hg in Group 2 vs 0.27 ± 0.1μL/min/mm Hg in Group 3, P= .005). However, aqueous humor flow rate was not statistically different (2.47 ±0.9μL/min in Group 1 vs 2.13 ± 0.9μL/min in Group 2 vs 2.25 ± 0.7μL/min in Group 3, P= .3). There was also no significant difference in calculated uveoscleral outflow. This is the first aqueous humor dynamics study in patients with uveitic glaucoma/OHT and recurrent anterior uveitis compared with age-matched controls. We have demonstrated that the elevated intraocular pressure seen in the uveitic glaucoma/OHT eyes (3-6 attacks) was due to reduced tonographic outflow facility. The aqueous humor flow rate was not detectibly different, nor did the calculated uveoscleral outflow demonstrate any discernible difference. However, the exact mechanism remains to be elucidated.