Abstract
Purpose: :
To compare the baseline aqueous humor dynamics in patients of African and white Caucasian origin with previously untreated primary open angle glaucoma (POAG) and ocular hypertension (OHT).
Methods: :
63 participants divided into 3 groups: (I) African origin subjects with POAG or OHT (n=29), (II) white Caucasian participants with POAG or OHT (n=22) and (III) healthy volunteers as controls (n=12) were enrolled in this prospective, observational longitudinal study. All aqueous humor parameters were taken between 9am and 12pm on a same day. Intraocular pressure (IOP) was measured by pneumatonometer; morning aqueous humor flow rate (F) was measured by fluorophotometry and an electronic Schiötz tonography was used to measure the trabecular outflow facility (Ft). Uveoscleral outflow (Fu) was calculated using the Goldman’s equation with assumed episcleral venous pressure of 10mmHg. Differences were analyzed by using Mann-Whitney U for group mean comparisons and by linear regression analysis. Only one randomly chosen eye from each subject was included in this analysis.
Results: :
Mean age was 59.24 +/- 12.73 years (mean +/- SD), 62.47 +/- 12.83 years and 52.54 +/- 13.69 years for the black and white affected and control subjects respectively (p=0.21). In the controlled eyes, the outflow facility (Ft=0.21 +/-0.07 µl/min/mmHg; p=0.001) and the intraocular pressure (17.02+/- 2.47 mmHg; p < 0.0001) were significantly different from the affected. There were no significant differences between the control and affected subjects regarding aqueous flow rate (1.94 +/-0.76 µlmin; p=0.55) and uveoscleral outflow (0.41 +/- 0.90 µl/min; p=0.67). In the comparison between the two racial groups, IOP (white, 24.12 +/- 3.84 mmHg; black 23.38 +/- 3.13 mmHg; p=0.58), outflow facility (white, 0.12 +/- 0.06 µl/min/mmHg; black 0.14+/-0.07 µl/min/mmHg; p=0.48) and aqueous flow rate (white, 2.29 +/- 0.83 µlmin; black 1.96 +/- 0.66 µlmin) did not differ significantly (p=0.2). The mean uveoscleral outflow was much lower in the black affected subjects (0.12 +/- 1.14 µl/min) compared with the white affected subjects (0.50 +/- 1.41 µl/min), although this difference was not statistically significant (p=0.27).
Conclusions: :
There is a trend of lower uveoscleral outflow in the patients of African origin with POAG and OHT, although the results were not significant. Otherwise no difference in IOP, tonographic outflow facility and aqueous humor flow rate was found among patients with POAG and OHT of different racial origins.
Keywords: aqueous • outflow: trabecular meshwork • intraocular pressure