Additive Role of Optical Coherence Tomography Angiography Vessel Density Measurements in Glaucoma Diagnoses

This study compared the glaucoma diagnostic abilities of optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA). In addition, the possibility of enhancing diagnostic capability by combining the two modalities was investigated.

A total of 131 healthy eyes and 113 glaucomatous eyes were imaged by both OCT and OCTA. In OCT, glaucoma was defined as when the color of the superior or inferior quadrant of the peripapillary retinal nerve fiber layer thickness map was yellow (borderline, <5%) or red (outside normal limits, <1%). In OCTA, glaucoma was determined using the cut-off value of the superior or inferior peripapillary vessel density, calculated after receiver operating characteristic curve analysis. Sensitivity and specificity were determined by OCT alone, by OCTA alone, or by OCT and OCTA combined.

The sensitivity of OCT (86.7%) was better than that of OCTA (74.3%), whereas the specificity of OCTA (87.0%) was better than that of OCT (67.9%). When these two modalities were combined, both sensitivity and specificity were enhanced (90.3% and 92.4%, respectively). Among the 131 eyes, 32 were misdiagnosed as glaucomatous by OCT but accurately diagnosed as normal by OCTA. These eyes were myopic, with a longer axial length and a thinner and temporally displaced peak of peripapillary retinal nerve fiber layer thickness, causing the false positive result in OCT.

When OCTA was combined with OCT, the specificity of glaucoma diagnoses were enhanced. OCTA may compensate for the shortcomings of OCT in the diagnosis of glaucoma.