Abstract
Purpose: :
Although risk associations of branch retinal vein occlusion (BRVO) has been investigated in various studies, it is still difficult to predict incident BRVO. What is more difficult is to predict which eye in an individual (i.e., right or left eye) develops BRVO where systemic risk factors are mostly shared. Therefore, we aimed to identify potential retinal vascular changes related to BRVO by comparing eyes developing BRVO and its contra-lateral eye as controls.
Methods: :
We identified 25 persons who developed BRVO and retrospective archives of retinal images from 1 to 5 years prior to incident BRVO from a database for health screening program at Osaka Health Science Center, Osaka Japan. We quantitatively measured retinal vascular calibre (central retinal artery, vein equivalent and arterio-venous ratio [CRAE, CRVE and AVR]) and the fractal dimensions of retinal vascular pattern using semi-automated standardized software. Measurements in eyes developing BRVO (based on the retinal images from 1-5 years prior to BRVO) were compared to those in the contra-lateral eye at matching time as controls.
Results: :
Retinal arteriolar caliber of 2-year, 1-year prior to develop BRVO and when BRVO presented was 158.6 µm, 160.7 µm, and 156.4 µm, respectively; retinal venular calibre of 2-year, 1-year prior to develop BRVO and when BRVO presented was 222.2 µm, 230.0 µm and 232.2 µm, respectively. Compared to control eyes at matching time, eyes developing BRVO had -7.3 smaller arteriolar caliber (157.5 µm vs. 164.8 µm; p=0.14), and +6.7 larger venular caliber (232.5 vs. 225.8; p=0.77) in 1-5 years prior to BRVO, but these were not statistically significant. AVR in eyes developing BRVO was -0.06 smaller than that in controls (0.68 vs. 0.73; p= 0.03). Fractal dimensions in eyes developing BRVO was -0.01 smaller (1.43 vs 1.44), but was not statistically significant (p= 0.37). Traditional arterio-venous nicking was associated with BRVO in 55%. Isolated retinopathy signs (retinal haemorrhages and cotton-wool spots) were observed in 45% 1-5 years prior to the incident BRVO.
Conclusions: :
We found that eyes developing BRVO had significantly smaller AVR compared to the contra-lateral eyes suggesting that discrepancy of AVR between eyes has a potential to be a marker of predicting incident BRVO. Also isolated retinopathy signs could be associated with BRVO as ocular risk characteristics. These findings warrant further validation in longitudinal studies.
Keywords: clinical (human) or epidemiologic studies: risk factor assessment • vascular occlusion/vascular occlusive disease • retina