Structural Changes of the Retina After Branch Retinal Artery Occlusion: Imaging and Quantification With Spectral Domain-OCT

Abstract

Purpose: : To investigate structural changes in the retinal architecture following branch retinal artery occlusions (BRAO) using spectral domain optical coherence tomography (SD-OCT).

Methods: : In this prospective, observational study 5 patients with acute BRAO and 15 patients 1 to 3 years after BRAO were analyzed using a Spectralis HRA+OCT device (Heidelberg Engineering). Patients with acute BRAO were studied within 48 hours after the first onset of symptoms and at monthly intervals thereafter until month 6. Thickness measurements of the different retinal layers were performed on single A-scans at 5 locations within affected areas and within anatomically corresponding non-affected areas. We analyzed retinal nerve fibre layer together with the ganglion cell layer (NFL/GCL), inner plexiform layer (IPL), inner nuclear layer (INL) and outer plexiform layer together with the outer nuclear layer (OPL/ONL).

Results: : SD-OCT images allowed for delineation of retinal layers in unaffected as well as in edematous retinal areas. Quantitative evaluation of layer thickness revealed a mean increase of NFL/GCL by 20 %, of IPL by 146 %, of INL by 66 % and of OPL/ONL by 30 % in acute edema when compared to corresponding unaffected areas. Regression of layer thickness was observed at month 1 and 2 without possible distinction between NFL/GCL, IPL and INL at month 3 (mean decrease by 132 %). Stable retinal atrophy was reached at month 4, no significant change was observed thereafter. The ONL remained at physiologic thickness levels in patients with chronic BRAO.

Conclusions: : SD-OCT is a useful imaging technique for studying changes of retinal architecture following BRAO. Thickness changes of single retinal layers can be visualized in detail and followed over time. In vivo assessment of macular edema secondary to BRAO can be of value to gain further insight in the pathophysiology of retinal ischemia.

Keywords: ischemia • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina