Differentiating Occult Branch Retinal Artery Occlusion from Primary Open-angle Glaucoma

Clinical findings in occult branch retinal artery occlusion (BRAO) can mimic those of primary open-angle glaucoma (POAG). Because management of these conditions substantially differs, accurate diagnosis is crucial. Our comparative analysis indicates that specific macular thickness variables reliably differentiate these conditions and that macular scanning may enhance routine glaucoma evaluation.

The aim of this study was to identify clinical factors that reliably and efficiently identify occult BRAO masquerading as POAG.

All subjects had comprehensive eye examinations including measurements of retinal nerve fiber layer and macular thickness (MT) using spectral-domain optical coherence tomography (SD-OCT). All subjects were asymptomatic for previous acute vision loss episodes, had optic nerve appearances suggestive of glaucoma, and exhibited SD-OCT retinal nerve fiber layer thinning with corresponding visual field loss. Macular thickness scans were divided into 64 individual thickness blocks with thin MT blocks defined by the lower 99% confidence interval from a group of normal eyes. We defined BRAO by the presence of regional inner retinal thinning with lack of inner-layer stratification on macular SD-OCT b-scan images that spatially corresponded with arteriolar distribution and visual field loss location. Primary open-angle glaucoma eyes were selected to match the BRAO eyes by age and disease severity. Pairwise and receiver operating characteristic curve analyses were used to compare occult BRAO and POAG eyes.

Compared with POAG (n = 52), occult BRAO eyes (n = 11) demonstrated lower cup-disc ratio, greater intereye and intraeye (superior vs. inferior) MT asymmetry, and higher frequency of thin MT blocks (<200 μm). Area under the receiver operating characteristic curve (AUC) for differentiating these conditions was highest for intraeye MT asymmetry (AUC = 0.990 [95% confidence interval, 0.925 to 1.000]) and number of thin MT blocks (AUC = 0.993 [95% confidence interval, 0.929 to 1.000]).

Macular thickness parameters provided accurate and efficient diagnostic capability in this study. Considering the clinical implications of inaccurate diagnosis, macular scanning may be important in baseline glaucoma evaluation.