Abstract
Purpose:
To investigate the utility of macular thickness (MT) parameters to differentiate between eyes with occult branch retinal artery occlusion (BRAO) and primary open-angle glaucoma (POAG).
Methods:
We retrospectively identified consecutive patients presenting over a 6-month period who were suspected of having POAG based on optic nerve and visual field findings but were subsequently diagnosed with occult BRAO after spectral-domain optical coherence tomography (SD-OCT) macular scans were reviewed. Specifically, BRAO was diagnosed when SD-OCT macular scans demonstrated severe inner retinal layer loss that spatially corresponded with arteriolar distribution, neuroretinal rim thinning, and visual field loss. For this study, BRAO subjects were also required to be asymptomatic and unaware of any prior retinal artery occlusion episodes. POAG subjects, who were selected from a longitudinal study at our institution, were matched to the BRAO group for age and severity of visual field loss as defined by mean defect (MD) on standard automated perimetry (SAP). All subjects had comprehensive eye examinations including SD-OCT imaging, and statistical methods were employed to determine the clinical, functional, and structural features that best distinguished between BRAO and POAG.
Results:
We studied 10 BRAO and 52 POAG subjects. We found no differences between groups for age, intraocular pressure, MD, pattern standard deviation, cup/disc ratio (CDR) asymmetry, global retinal nerve fiber layer (RNFL) thickness, global RNFL thickness asymmetry, and total, inferior, and superior MT. Inter-eye and intra-eye MT asymmetry parameters, however, showed significantly greater asymmetry in BRAO compared to POAG. CDR was also larger in POAG (0.78±0.12) versus BRAO (0.65±0.11) eyes (p=0.002). Regression analysis identified intra-eye (superior versus inferior) MT asymmetry as the best discriminator between BRAO and POAG, and ROC analysis found an area under of the curve (AUROC) of 0.989 for this parameter.
Conclusions:
Our findings demonstrate that structural and functional findings in occult BRAO can mimic typical findings of POAG. Differentiation of these conditions, however, can be accomplished using SD-OCT macular asymmetry parameters in conjunction with review of individual SD-OCT b-scans to identify the severe inner retinal loss that defines BRAO insult.