Internal and External Retinal Arteriolar Diameter and Retinal Nerve Fiber Layer Thickness in Patients with Primary Open-Angle Glaucoma

Purpose To investigate internal and external retinal arteriolar diameters and to evaluate the relationship between retinal nerve fiber layer (RNFL) thickness and retinal arteriolar diameter in patients with primary open-angle glaucoma (POAG). Methods This single-site, prospective, cross-sectional study included 20 patients with POAG (20 eyes) and 20 age- and sex-matched healthy controls (20 eyes) with no history of systemic vascular disease. The internal and external diameters of the arterioles were assessed in-vivo by scanning laser Doppler flowmetry. RNFL thickness was measured using spectral-domain optical coherence tomography. Results Both the internal and external arteriolar diameters were smaller in eyes with POAG than in control eyes, although only the internal diameters were significantly smaller (P = 0.04 versus P = 0.23). A multivariate linear regression analysis demonstrated a significant positive correlation between RNFL thickness and both external (P = 0.024) and internal (P = 0.003) arteriolar diameters in eyes with POAG. No significant correlation was found between RNFL thickness and these variables in the control group. Conclusions The internal arteriolar diameter was smaller in patients with POAG than in normal subjects, and was significantly correlated with RNFL thickness in POAG patients. To our knowledge, this is the first study to report that a narrower internal arteriolar diameter may be related to RNFL thinning in POAG patients.