Does aqueous humor outflow (AHO) occur uniformly from the eye?
Studies have reported wide variation in the AHO in glaucomatous and non-glaucomatous eyes.
A study using aqueous angiography (AA) was performed by Beri et al, to evaluate AHO pathways in nonglaucomatous subjects. The study found there is a segmental pattern of outflow, with the nasal quadrant having the maximum and the temporal quadrant having the least AHO pathways.
A cross-sectional, observational, single-center study recruited 30 subjects with visually significant age-related cataract planned for phacoemulsification. AA was performed using indocyanine green (ICG) dye 0.1% just before phacoemulsification. Images were analyzed at 60 seconds from the injection of ICG dye for angiographic signal intensity in 4 quadrants and 8 sectors, circumferentially (360 degrees) along the limbus. Signal intensities were evaluated and compared between quadrants and sectors as the primary outcome measure. Signal intensities between males and females, right and left eyes were assessed as secondary outcome measures, using appropriate statistical tests.
Segmental AHO was noted in all patients. The median signal intensity was highest in the nasal quadrant [45.95(35.59–54.34)] followed by the inferior [31.56 (24.82–41.71)], superior [30.16 (28.2–37.43)], and temporal [26.66 (22.92–34.33)] quadrants, and their difference was statistically significant (P<0.0001). Median signal intensity among 8 sectors was highest in the nasosuperior sector [23.05 (17.14–29.20)] and least in the temporoinferior sector [12.98 (10.82–17.51)] (P<0.0001).
No significant difference was observed in median signal intensities between males [132.83 (115.82–174.18)] and females [143.74 (122.43–166.00)] (P=0.771) and right eyes [143.74 (118.53–170.6)] and left eyes [133.51 (122.43–153.86)] (P=0.967).
Such findings have been reported from glaucomatous eyes also. These reports can be used to find the optimum place for MIGS insertion and possibly for performing Trabeculectomy.
REFERENCE:
Beri, Nitika MS*; Patil, Anuja MD†; Midha, Neha MD‡; Angmo, Dewang MD†; Bari, Aafreen MD†; Sharma, Namrata MD†; Dada, Tanuj MD†. Quantitative Assessment of Functional Aqueous Humor Outflow by Aqueous Angiography. Journal of Glaucoma 34(11):p 888-894, November 2025. | DOI: 10.1097/IJG.0000000000002617
