Differences in the Association of Age, Retrobulbar Blood Flow, Retinal Structural Damage and Visual Fields between Right and Left Eyes with Glaucoma

Abstract

Purpose: : To evaluate potential differences in the relationship between visual field loss, retinal structural changes, age, and retrobulbar blood flow between right and left eyes in patients with primary open angle glaucoma (OAG).

Methods: : In 116 OAG patients (age 66.9 +/- 10.9 years) participating in the Indianapolis Glaucoma Progression Study a comparison was done between the left (n=53) and right (n=63) eyes with respect to the retrobulbar blood flow, as measured by color Doppler imaging, retinal microcirculation, as measured by confocal scanning laser Doppler flowmetry and retinal structure, as measured by optical coherence tomography. Visual fields were assessed by Humphrey Visual Field Analyzer 24-2 SITA standard program. Statistical analysis was performed by Mann-Whitney U test, Spearman correlation and standard method multivariate linear regression analysis.

Results: : No differences were found between right and left eyes in terms of retinal or retrobulbar blood flow and retinal structural parameters when analyzing the entire sample of OAG patients. When assessing OAG patients aged 70 years or less with a baseline AGIS score of zero, the patients in which the left eye was studied tended to have a higher mean retinal neural fiber layer (RNFL) thickness and higher ophthalmic artery (OA) vascular resistance (P=0.052 and P=0.089, respectively). In bivariate analysis, nasal short posterior ciliary arterial (NPCA) resistivity was positively associated with AGIS score changes (from baseline to 1.5 year) in the right eye (r=0.471, P=0.036). However, no associations were found between the AGIS score changes and resistance indices of OA, central retinal artery and nasal and temporal short posterior ciliary arterial resistivity in the left eye (P>0.1). In multivariate linear regression analysis, AGIS score changes (increased vs. stable or decreased) were related to age and NPCA resistance in the right eye (adjusted r²=0.361, P=0.015), but this was not significant (P=0.342) in the left eye.

Conclusions: : Early glaucomatous structural damage and visual field loss may be dependent on retrobulbar blood flow as well as age; although this relationship may not be bilateral in presentation. Other factors potentially contributing to visual field loss in different eyes, such as an inflammatory process, should be investigated.

Keywords: blood supply • nerve fiber layer • visual fields