Hemiretinal Asymmetry in Optical Coherence Tomography Angiography Parameters in Healthy, Glaucoma Suspect, and Glaucoma Eyes of the African American Eye Disease Study

Abstract

Purpose : Glaucomatous damage often starts focally in one hemisphere. This study investigates hemiretinal asymmetry in peripapillary optical coherence tomography angiography (OCTA) parameters in healthy, glaucoma suspect, and glaucoma eyes and its ability to detect early glaucomatous damage in the African American Eye Disease Study (AFEDS).

Methods : 4135 eyes from 2127 African Americans 40 years and older in Inglewood, California received 6x6-mm optic disc scans on spectral-domain OCTA. Custom software quantified vessel diameter (VD), vessel area density (VAD), vessel skeleton density (VSD), vessel perimeter index (VPI), vessel complexity index (VCI), flow impairment zone (FIZ), and flux. Circumpapillary retinal nerve fiber layer (RNFL) thickness was measured from OCT scans. 711 eyes met inclusion/exclusion criteria. Two age- and sex-matched groups were constructed: 1) 260 healthy and 87 glaucoma suspect eyes, and 2) 95 healthy and 34 glaucoma eyes. Hemiretinal asymmetry (hVD, hVAD, hVSD, hVPI, hVCI, hFIZ, and hFlux) was defined as absolute difference between superior and inferior hemiretinal values. Diagnostic ability was evaluated with area under the receiver operating curve (AUC). A linear discriminant function (LDF) was constructed with all hemiretinal asymmetry and global OCTA parameters.

Results : Glaucoma suspect eyes had significantly higher hemiretinal asymmetry in OCTA parameters than healthy eyes: hVD (p = 0.007), hVAD (p = 0.028), hVSD (p < .0001), hVPI (p < .0001), and hFIZ (p = 0.011). Based on AUC, hemiretinal asymmetry in OCTA parameters was better at detecting glaucoma suspect than global OCTA parameters: hVD (0.623), hVAD (0.577), hVSD (0.640), hVPI (0.759), hVCI (0.559), and hFIZ (0.579). While glaucoma eyes had significantly higher hemiretinal asymmetry in some OCTA parameters than healthy eyes, global OCTA parameters were better at detecting glaucoma than hemiretinal asymmetry based on AUC: VD (0.767), VAD (0.813), VSD (0.807), VPI (0.814), VCI (0.814), FIZ (0.785), and flux (0.800) (Table 1). LDF yielded the highest AUC for glaucoma suspect (0.805) and glaucoma (0.889).

Conclusions : Hemiretinal asymmetry in OCTA parameters was better than global OCTA parameters at distinguishing glaucoma suspect eyes from healthy eyes, but this advantage was not seen in detecting glaucoma eyes, where damage becomes more diffuse.

This is a 2020 ARVO Annual Meeting abstract.