Decreased Retrobulbar Blood Flow as a Predictor for Glaucomatous Visual Field Changes

Abstract

Purpose: : To examine the relationship between retrobulbar blood flow and visual field progression parameters in patients with primary open angle glaucoma (OAG).

Methods: : An analysis of 73 patients with OAG (mean age 68.5; 38 female) who completed 2 years of follow up in the Indianapolis Glaucoma Progression Study was performed. Retrobulbar blood flow was assessed by color Doppler imaging (CDI) in the ophthalmic artery (OA), central retinal artery (CRA), temporal (TPCA) and nasal (NPCA) short posterior ciliary arteries measuring peak systolic (PSV) and end diastolic (EDV) blood flow velocities and vascular resistance (RI). Visual field mean deviation defect (MD), pattern standard deviation defect (PSD) and calculated advanced glaucoma intervention (AGIS) score as measured by Humphrey Visual Field Analyzer using the 24-2 SITA standard algorithm was performed. Multivariable linear regression models with rank-transformed data were analyzed for the change from baseline for each measurement with the following variables included in all models: sex, race (white vs. non-white), age, baseline intraocular pressure (IOP) and the baseline value for the measurement. Stepwise model selection procedures were then used to evaluate CDI measured blood flow parameters for predicting changes in visual field outcomes, with only measurements statistically significant at p<0.05 retained in the model.

Results: : In a bivariate analysis, AGIS score was negatively correlated with OA PSV, CRA EDV, NPCA EDV and TPCA EDV (R=-0.263, p=0.04; R=-0.366, p=0.004; R=-0.318, p=0.012, R=-0.265, p=0.039 respectively) and positively correlated with CRA and NPCA RI (R=0.328, p=0.01; R=0.357, p=0.005 respectively). PSD was positively correlated with CRA and NPCA RI. In a multivariable regression analysis adjusted for age, sex, race and IOP, the change in CRA EDV was the only predictor for changes in AGIS score (adjusted R-squared=0.11, p=0.005).

Conclusions: : A long term decrease in the retrobulbar blood flow may be predictive of glaucomatous deterioration in the visual field in patients with OAG.

Keywords: blood supply • visual fields • optic disc