Morphologic and functional changes in retinal vessels associated with branch retinal vein occlusion

Area of Science:

• Ophthalmology
• Medical Imaging
• Vascular Biology

Background:

• Branch retinal vein occlusion (BRVO) is a common retinal vascular disease.
• Understanding the morphologic and functional changes in BRVO is crucial for diagnosis and treatment.
• Optical coherence tomography (OCT) offers high-resolution cross-sectional imaging of retinal structures.

Purpose of the Study:

• To investigate the morphologic and functional alterations in retinal veins affected by BRVO.
• To utilize sequential thin-sectioning optical coherence tomography (OCT) for detailed vascular analysis.
• To elucidate the role of arteriovenous (A/V) crossings in the pathogenesis of BRVO.

Main Methods:

• Prospective, observational, cross-sectional study of 25 patients with acute BRVO.
• High-resolution OCT imaging of major retinal veins, arteries, and A/V crossings.
• In vitro simulation of retinal blood flow to validate OCT findings.

Main Results:

• OCT revealed distinct hyperreflectivity patterns in normal versus BRVO-affected vessels.
• Physiologic vessels showed an hourglass pattern of internal hyperreflectivity, absent in BRVO.
• BRVO mechanisms varied based on A/V crossing anatomy (arterial vs. venous overcrossing), with thrombi detected downstream in 21 eyes, significantly associated with ischemia.

Conclusions:

• Sequential OCT imaging provides detailed 3D visualization of retinal vasculature in BRVO.
• Findings suggest two distinct pathophysiological mechanisms for BRVO.
• The relative anatomical positioning of crossing vessels at A/V crossings plays a critical role in BRVO development.