Macula Vessel Density and Thickness in Early Primary Open-Angle Glaucoma

Abstract

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

Design: Cross-sectional study.

Methods: 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.

Results: 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).

Conclusions: 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.

Figure 1

Boxplots illustrating the distribution of whole image (left) and perifoveal (right) percent loss of ganglion cell complex (GCC) vessel density and thickness in pre-perimetric glaucoma and early glaucoma eyes. The medians are represented by horizontal lines in the gray boxes. Error bars denote interquartile range. In early glaucoma, percent loss of GCC thickness is greater than vessel density. P-values are based on multivariable analysis controlling for age, gender, race, self-reported diabetes and hypertension, and scan quality.

Figure 2

Microvasculature and thickness measurements in a pre-perimetric glaucoma eye (top 2 rows) and an early glaucoma eye (bottom 2 rows). Top and third row: optic disc photograph (left) and 24-2 standard automated perimetry (SAP) results. Second and forth row: optical coherence tomography angiography (OCT-A) macula scan showing the superficial vascular plexus (left); corresponding color-coded flow density map of the superficial vascular plexus flow density (middle; the warmer the color, the greater the flow); and color-coded thickness map of ganglion cell complex (GCC) (right; the warmer the color, the greater the thickness) deriving from spectral domain optical coherence tomography (SD-OCT) macula scan of the identical slab. The mean deviation and pattern standard deviation of the pre-perimetric eye are −0.07 dB and 1.62 dB. This pre-perimetric case shows similar severity of vessel density and GCC thickness percent loss of 6.3% and 7.9% respectively. While the early glaucoma case, which with mean deviation and pattern standard deviation as −1.63 dB and 3.43 dB, shows greater loss in GCC thickness (14.7%) comparing to vessel density (6.7%).

Figure 3

Scatterplots illustrating the linear and quadratic association between percent loss of GCC thickness and vessel density in pre-perimetric glaucoma eyes and early glaucoma eyes.