Retinal vessel diameter, retinal nerve fiber layer thickness, and intraocular pressure in Korean patients with normal-tension glaucoma

Purpose To investigate the retinal vessel diameter and evaluate the relationship of the retinal nerve fiber layer (RNFL) thickness with retinal vessel diameter and intraocular pressure (IOP) in patients with normal-tension glaucoma (NTG). Design A prospective, cross-sectional study. Methods This study included 60 previously untreated patients with NTG (60 eyes) and 45 age- and sex-matched healthy controls (45 eyes) that had no history of systemic vascular disease at a single institution. The diameters of the central retinal arteries and veins were measured on retinal photographs. The central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) were calculated using the revised Parr-Hubbard formula. The RNFL thickness was measured using Stratus optical coherence tomography. Results The mean central retinal arteriolar (P = .000) and venular (P = .000) diameters were significantly smaller in the eyes with NTG than in the normal eyes. Multivariate linear regression analysis demonstrated a significant positive correlation between the RNFL thickness and CRAE (P = .014), and a negative correlation between the RNFL thickness and IOP (P = .005) in the eyes with NTG. However, there was no significant correlation between the RNFL thickness and the independent variables in the control group (P = .112). Conclusion The patients with NTG had smaller diameters of the central retinal vessels than the normal subjects. Both IOP and CRAE were significantly associated with RNFL thickness in the patients with NTG. Our results suggest that narrower retinal vessels and higher IOP may be related to the thinning of the RNFL in patients with NTG.