To characterize and compare the ganglion cell complex (GCC) thickness and macula vessel density in preperimetric and early primary open-angle glaucoma (POAG) eyes.

Cross-sectional study.

Fifty-seven healthy, 68 preperimetric, and 162 early POAG eyes enrolled in the Diagnostic Innovations in Glaucoma Study. Optical coherence tomography angiography (OCT-A)-based superficial macula vessel density and OCT-based GCC thickness were evaluated simultaneously. Percent loss from normal of GCC thickness and macula vessel density was compared. Area under the receiver operating characteristic curve was used to describe the diagnostic utility.

Both GCC thickness and vessel density were significantly lower in preperimetric and early POAG eyes compared to healthy eyes. Compared to the preperimetric POAG group, the early POAG group showed larger GCC thickness percent loss (whole image 4.72% vs 9.86%; all P < .01) but similar vessel density percent loss (whole image 4.97% vs 6.93%; all P > .05). In preperimetric POAG, GCC thickness and vessel density percent losses were similar (all P > .1). In contrast, in early POAG, GCC thickness percent loss was larger than that of vessel density (all P ≤ .001). To discriminate preperimetric or early glaucoma eyes from healthy eyes, GCC thickness and macula vessel density showed similar diagnostic accuracy (all P > .05).

Both GCC thinning and macula vessel density dropout were detectable in preperimetric and early POAG eyes. GCC loss was greater than macula vessel density loss in early perimetric POAG. However, OCT-A and OCT measurements showed similar efficiency to detect early glaucoma.