Branch retinal vein occlusion may be attributed to distinct morphologic changes related to the location of crossing vessels, according to a study.
The prospective study included 25 eyes of 25 patients with acute BRVO. Diagnosis of BRVO was based on fluorescein angiography and fundus examination. Eyes with central retinal vein occlusion or diabetic retinopathy, glaucoma or cataracts were excluded.
Investigators used thin sectioning and the Spectralis HRA+OCT system (Heidelberg Engineering) to examine major retinal veins, arteries and arteriovenous (A/V) crossings, and to mimic and scan retinal blood flow in vitro.
Study results showed arterial overcrossing in 17 eyes and venous overcrossing in eight eyes at affected A/V crossings.
Intravenous thrombi were identified downstream from the A/V crossing in 21 eyes. There was a statistically significant association between presence of thrombus and an ischemic pattern in BRVO (P = .036).