Purpose/aim: To identify retinal vascular features that precede the development of branch retinal vein occlusion (BRVO) by comparing case eyes and fellow eyes.
Materials and methods: We identified 25 persons who attended an annual health screening program at Osaka Health Science Center, Osaka, Japan, and then developed BRVO in one eye between 1995 and 2009. We retrospectively reviewed retinal images of these subjects taken 1-5 years prior to the development of BRVO and compared the prevalence of retinal vascular features between case eyes and contralateral fellow eyes. Potential local retinal vascular features considered were (1) severe arterio-venous (AV) nicking, (2) a smaller angle at the crossing of the arteriole and venule, (3) double crossing, (4) crossing near venular bifurcation and (5) isolated retinopathy. The central retinal artery equivalent (CRAE), vein equivalent (CRVE) and AV ratio (CRAE divided by CRVE) were quantitatively estimated using a standardized imaging software (University of Wisconsin).
Results: Compared to the fellow eye, severe AV nicking (39.1% versus 2.6%, <0.001), isolated retinopathy (47.8% versus 7.69%, p < 0.001) and a smaller angle at the crossing site (82.6% versus 46.2%, p = 0.005) were more prevalent in eyes with BRVO compared with fellow eyes. Case eyes had a significantly smaller AV ratio at 1-5 years prior to the development of BRVO compared with fellow eyes (0.68 versus 0.73, p = 0.03).
Conclusions: In addition to severe AV nicking, a well-known sign linked to BRVO, this study identified two new potential retinal vascular features--isolated retinopathy and a smaller angle at the crossing site--associated with BRVO development. We also found that a discrepancy in the AV ratio between eyes (i.e. a smaller AV ratio than the fellow eye) can be a quantitative indicator of a higher BRVO risk. These findings warrant further validation in longitudinal studies.