Retinal Microcirculation As A Predictor For Retinal And Optic Nerve Structural Changes In Patients With Primary Open Angle Glaucoma

Abstract

Purpose: : To examine the relationship between the retinal microcirculation and retinal nerve fiber layer (RNFL) thickness, and optic nerve head structural changes in patients with primary open angle glaucoma (OAG).

Methods: : An analysis of 103 patients with OAG (mean age 67.0; 60 female) participating in the Indianapolis Glaucoma Progression Study was performed after their 18 month follow up visit. An additional analysis of 73 patients with OAG (mean age 68.5; 38 female) who finished their 2 years visit was also performed. Retinal capillary perfusion was examined with confocal scanning laser Doppler flowmetry. RNFL thickness and optic nerve head structure was assessed with optical coherence tomography (OCT). Multivariable linear regression models with log-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 baseline values. Stepwise model selection procedures were then used to evaluate retinal microcirculation for predicting RNFL and optic nerve structure, with only measurements statistically significant at p<0.05 retained in the models.

Results: : Multivariable linear regression showed that the percentage of zero blood flow pixels in the superior retina at the 18 months visit was the only predictor for cup to disk vertical ratio change (adjusted r-squared=0.51, p<0.0001). After 2 years, in a bivariate analysis, there was a negative correlation between the amount of superior zero blood flow pixels and RNFL average thickness (r=-0.318, p=0.013) and between superior mean blood flow and cup to disk horizontal ratio. Multivariable linear regression found the number of superior zero pixels was the only predictive value for RNFL average thickness (adjusted r-squared=0.085, p=0.017).

Conclusions: : Retinal regional perfusion insufficiency may be a significant predictor of glaucoma progression as assessed by structural changes in the optic nerve and RNFL.

Keywords: blood supply • imaging/image analysis: clinical • retina