Association Between Retrobulbar Blood Flow Velocities and Rim Area of the Optic Disc in Glaucomatous Optic Neuropathy

Abstract

Abstract: : Purpose: To assess the association between retrobulbar blood flow velocities measured by color Doppler imaging (CDI) and neuroretinal rim area measured by Heidelberg Retina Tomograph (HRT) in eyes with glaucomatous optic neuropathy. Methods: One randomly selected eye of 126 patients with glaucomatous optic neuropathy [mean standard automated perimetry (SAP) MD (±SD) = -3.17±4.8 dB] was examined. Mean patient age was 66.4±11.4 years. CDI retrobulbar blood velocities were measured at the ophthalmic artery (OA), central retinal artery (CRA), and the temporal and nasal short posterior ciliary arteries (TSPCA, NSPCA). Perfusion parameters were peak systolic velocity, end diastolic velocity, and resistance index. HRT optic disc parameters were global and regional (6 sectors) rim area. We also examined the association between perfusion and disc area because of the known relationship between rim area and disc area. Univariate linear regression was used to evaluate the association between perfusion parameters and HRT measurements. Additionally, a stepwise multiple linear regression model was used including: total rim area, regional rim area, disc area, age, systolic blood pressure, diastolic blood pressure, heart rate, IOP, and SAP MD. Results: Using linear regression, rim area was not significantly associated with perfusion of the OA, CRA, TSPCA or NSPCA (all p≷0.05). Total disc area was significantly associated (defined as p<0.05) with CRA resistance index (R₂=0.09, negative correlation). Using the multivariate model, rim area was not significantly associated with any perfusion parameters. Total disc area remained significantly associated with CRA resistance index (R₂=0.07). Age was significantly and most strongly associated with OA resistance index (R₂=0.26, positive correlation), followed by TSPCA resistance index, CRA resistance index, TSPCS end diastolic velocity, NSPCA resistance index, CRA end diastolic velocity, OA end diastolic velocity, and NSPCA end diastolic velocity (all range: R₂=0.05 to 0.20). Systolic blood pressure, diastolic blood pressure, and IOP were significantly associated with some CRA and TSPCA measures, with R ₂ ranging from 0.03 to 0.08. Conclusion: Rim area measured by HRT is not associated with perfusion parameters measured by CDI in GON patients. Optic disc area and age should be considered when evaluating perfusion in GON.

Keywords: 498 optic disc • 331 blood supply