Retinal Vessel Caliber and Glaucoma Incidence
In this population-based cohort study, researchers examined associations between quantitatively measured retinal vessel caliber and the 10-year incidence of primary open-angle glaucoma (OAG). The Blue Mountains Eye Study examined 3,654 persons at baseline and 2,461 persons at either five years, 10 years or both times. After excluding 44 subjects with OAG at baseline, 2,417 participants at risk of OAG at the five- or 10-year examinations were included.
The researchers measured retinal vessel calibers of baseline retinal photographs using a computer-based program and summarized them as central retinal artery and vein equivalents (CRAE, CRVE). They defined incident OAG as the development of typical glaucomatous visual field loss combined with matching optic disc rim thinning and an enlarged cup-to-disc (C:D) ratio of >0.7 or C:D asymmetry between the two eyes (≥0.3) at either the five- or 10-year examination. Additionally, they used generalized estimating equation models to account for correlation between eyes while adjusting for glaucoma risk characteristics including intraocular pressure (IOP) or ocular perfusion pressure (OPP). The researchers assessed the 10-year incidence of OAG as the main outcome measure.
They reported that 82 persons (104 eyes) developed incident OAG over the 10-year follow-up. After adjusting for age, sex, family history of glaucoma, smoking, diabetes, hypertension, hypercholesterolemia, body mass index, spherical equivalent refraction and C:D ratio, narrower CRAE was associated with higher risk of incident OAG (adjusted odds ratio [OR], 1.77; 95% confidence interval [CI], 1.12–2.79, per standard deviation decrease in CRAE). This association persisted after further adjustment for IOP (adjusted OR, 1.87; 95% CI, 1.14–3.05) or OPP (adjusted OR, 1.76; 95% CI, 1.11–2.78), and remained significant when analyses were confined to eyes with IOP <20 mmHg and C:D ratio <0.6 at baseline. Furthermore, there were no independent associations between CRVE and incident OAG.
Retinal arteriolar narrowing, quantitatively measured from retinal photographs, was associated with long-term risk of OAG. These data support the concept that early vascular changes are involved in the pathogenesis of OAG and suggest that computer-based measurements of retinal vessel caliber may be useful to identify people with an increased risk of developing the clinical stage of glaucoma.