Abstract
Purpose :
This study tested the hypothesis that aqueous vein (AqV) diameters are associated with intraocular pressure (IOP) reduction following phacoemulsification combined with a glaucoma angle surgery.
Methods :
The nasal ocular surface was imaged at 40x magnification with a red-free filter using a slit lamp imaging system (Zeiss Meditec, Dublin, CA) in 30 eyes from 20 adult patients with primary open angle glaucoma. Potential aqueous veins within 2 clock hours of the nasal meridian were identified and the largest vein was selected for further analysis. The cross-sectional pixel intensities of the AqV were collected using the VasoMetrics plugin in ImageJ (figure 1b) and a custom Mathematica program was used to calculate AqV diameters with a full-width half-maximum segmentation. Patients underwent a goniotomy (n=18) or placement of a trabecular bypass stent (n=12). Associations between AqV diameters with IOP reduction at post-operative month 3 were calculated using a Pearson correlation. A multivariable regression model incorporating age, number of pre-operative drops, AqV diameter and pre-operative IOP was used to determine pre-operative factors related to IOP reduction.
Results :
The mean pre-operative IOP was 20.5 ± 5.8 mm Hg with a mean reduction of 20.9 ± 12.6% at 3 months. The mean pre-operative AqV diameter was 100 ± 31.8 µm. The percent IOP reduction was found to be correlated with pre-operative AqV diameter (Pearson correlation coefficient = 0.764, p < 0.001) as seen in figure 2. Preoperative IOP (β = 0.71; 95% CI=0.05-1.37; p=0.036) and AqV diameter (β = 0.24; 95% CI=0.13-0.0.36; p<0.001) were found to be statistically significant predictors of IOP reduction in the multivariable model.
Conclusions :
Preliminary data suggests that the pre-operative diameter of the largest nasal AqV is a predictor of IOP reduction following angle surgery. This outcome may be related to the capacitance of aqueous veins in the region where the trabecular outflow is surgically enhanced. Future work will examine changes in AqV and aqueous fluid columns before and after angle surgery.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.