Vitreoretinal traction in impending branch retinal vein occlusion: A pathogenetic role?

Abstract

A 25-year-old woman noticed floaters in her left visual field since a few days earlier. She was positive for the heterozygous A1298C mutation on MTHFR gene, betafibrinogen gene –455G/A polymorphism, and 4G/5G plasminogen activator inhibitor-1 (PAI-1). Blood test and a systemic workup did not reveal any abnormality. Blood pressure was 120/80 mmHg. Visual acuity was 20/20 in both eyes. Following a complete ophthalmologic examination an impending upper temporal branch retinal vein occlusion (BRVO) was diagnosed ( Fig. 1). The patient was followed for one month without any particular treatment. Visual acuity remained unchanged and ophthalmic examination demonstrated improvement in the retinal vascular configuration with complete resolution of retinal hemorrhages, venous tortuosity and congestion ( Fig. 2). BRVO is the second most common vascular disorder of the retina, after diabetic retinopathy. It typically occurs at an arteriovenous (AV) crossing, where the retinal arteriole and venule share a common adventitial sheath (1). Although the pathogenesis of BRVO is not clear, there is evidence suggesting a multifactorial process including genetic, environmental and local factors. Mechanical narrowing of venous lumen may alter the normal blood flow downstream of the AV crossing, leading to turbulent flow. The preexisting endothelial vascular damage from different systemic Figure 1: Findings at first presentation of the patient. A) Fundus photograph of the left eye showing a moderate tortuous and engorged upper temporal retinal vein (white arrows), with some small flame-shaped retinal hemorrhages along the territory of the affected vessel (black arrows). B) Fluoresceingraphy disclosed delayed venous filling and a localised partial obstruction in the venous lumen near optic nerve (arrow). C) SD-OCT directed to the site of obstruction revealed a vitreovascular traction (arrow) and tissue elevation (asterisks) by an obliquely directed posterior hyaloids. D) SD-OCT dense protocol of false-color maps provided qualitative information of perivascular edema, showing an intense red colour at the involved blood vessel segment. A B