Comparison of OCT Angiography and Conventional Fluorescein Angiography in the Evaluation of Collateralization in Acute versus Chronic Branch or Hemi Retinal Vein Occlusion

Abstract

Purpose :
To describe the role of optical coherence tomography angiography (OCTA) in identifying collateralization in acute versus chronic branch retinal vein occlusion (BRVO) or hemi-retinal vein occlusion (HRVO).

Methods :
This retrospective cohort study reviewed 32 patients with BRVO/HRVO who were imaged with spectral-domain (RTVue XR Avanti, Optovue, Inc.; Cirrus AngioPlex, Carl Zeiss Meditec) or swept-source OCTA (Prototype, Carl Zeiss Meditec) at two retinal practices. Medical charts were reviewed for collateral vessels seen during clinical exam. En-face OCTA images of the superficial (SCP) and deep capillary plexuses (DCP) were generated and reviewed. Patients were categorized according to chronicity, with acute defined as < 6 months vs. chronic (≥ 6 months) from initial diagnosis. The likelihood of collateral vessels on OCTA in acute versus chronic groups was compared. Fisher exact test was used to assess agreement regarding identification of collaterals on OCTA, fluorescein angiography (FA) and clinical exam. Statistical significance was defined as p<0.05.

Results :
The 32 patients (19 female) had a mean age of 65 (range 42-93). Of the patients, 41% had acute and 59% had chronic BRVO/HRVO. Best-correct visual acuity was 20/56 (range 20/20–CF@6’, 0.45+/-0.43, mean+/-SD in logMAR). OCTA identified collateral vessels in 22/32 (69%) of cases (2 (9%) in SCP, 5 (23%) in DCP and 15 (68%) in both). Of the 17 patients that underwent both FA and OCTA, collateral vessels were identified by clinical exam in 9 (28%), by FA in 11 (34%) and OCTA in 11 (34%). OCTA and clinical examination for collaterals were in good agreement (p=0.002), with both FA and OCTA identifying collaterals in two cases not noted on clinical exam alone. There was perfect agreement between OCTA and FA in all 17 cases (p=0.000). Overall on OCTA, collateral vessels were significantly more likely found (t-test, p=0.024) in chronic (14/19, 74%) than acute cases (5/13, 38%).

Conclusions :
OCTA has depth-encoded information and is able to reliably identify collateral vessels in patients with BRVO/HRVO in perfect agreement with FA. Collateral vessels are seen within both capillary plexuses. Identifiable collateralization typically occurs after ≥ 6 months from the initial diagnosis of BRVO/HRVO.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.