The association between retinal vessel diameter and retinal nerve fiber layer thickness in asymmetric normal tension glaucoma patients.

PURPOSE: The aim of this study was to evaluate the associations between retinal vessel diameter and retinal nerve fiber layer (RNFL) thickness in patients with normal tension glaucoma (NTG).
METHODS: This study included 67 untreated patients with asymmetric NTG, with no evidence of glaucoma in the contralateral eyes, and 48 age- and sex-matched normal control subjects. We included patients from 20 to 70 years of age who had no history of hypertension, diabetes, or other vascular diseases. All subjects underwent detailed eye examinations that included red-free photography, stereoscopic optic disc photography, automated perimetry, and measurement of RNFL thickness with optical coherence tomography. We compared RNFL thicknesses, temporal retinal arteriolar diameters (TRAD), and temporal retinal venular diameters (between quadrants with and without RNFL defects) with computer-assisted imaging software.
RESULTS: The mean diameter of the temporal retinal vessels in the quadrants with RNFL defects were significantly smaller in patients with NTG than in those with quadrants without RNFL defects (P < 0.001) and in control subjects (P < 0.001). TRADs were correlated with RNFL defects and RNFL thicknesses (P < 0.05) in binary logistic regression analysis and in multiple linear regression analysis (P < 0.001). There were no statistically significant differences between vessel diameters in control subjects and those in nondefective quadrants of the affected NTG eyes or the unaffected eyes of patients with NTG.
CONCLUSIONS: Our results show that narrower retinal vessels are found in areas of RNFL defects. Considering previous reports and our analysis, this is likely due to the decreased demand for retinal blood flow in damaged areas of the retina.