Optical Coherence Tomography Angiography Compared With Optical Coherence Tomography Macular Measurements for Detection of Glaucoma

Abstract

Importance: Whether optical coherence tomography angiography (OCT-A) outperforms OCT to detect glaucoma remains inconclusive.

Objective: To compare (1) the diagnostic performance for detection of glaucoma and (2) the structure-function association between inner macular vessel density and inner macular thickness.

Design, setting, and participants: This cross-sectional study included 115 patients with glaucoma and 35 healthy individuals for measurements of retinal thickness and retinal vessel density, segmented between the anterior boundary of internal limiting membrane and the posterior boundary of the inner plexiform layer, over the 3 × 3-mm2 macula using swept-source OCT. All participants were Chinese. Visual sensitivity corresponding to the 3 × 3-mm2 macular region was expressed in unlogged 1/lambert for investigation of the structure-function associations. Diagnostic performance was evaluated with area under the receiver operating characteristic curves (AUCs). The study was conducted between January 12, 2016, and December 12, 2016.

Main outcomes and measures: Area under the receiver operating characteristic curve and R2 analysis.

Results: Of the 115 patients with glaucoma, 42 (36.5%) were women (mean [SD] age, 53.5 [13.4] years); of the 35 individuals with healthy eyes, 25 (71.4%) were women (age, 60.6 [5.9] years). Inner macular vessel density and thickness were 4.3% (95% CI, 2.4%-6.1%) and 21.1 μm (95% CI, 17.4-24.9 μm) smaller, respectively, in eyes with glaucoma compared with healthy eyes. The AUC of mean inner macular thickness for glaucoma detection was greater than that of mean inner macular vessel density (difference, 0.17; 95% CI, 0.01-0.31; P = .03). At 90% specificity, the sensitivity of mean inner macular thicknesses for detection of glaucoma was greater than that of mean inner macular vessel densities (difference, 29.2%; 95% CI, 11.5%-64.6%; P = .02). The strength of the structure-function association was stronger for mean inner macular thickness than mean inner macular vessel density in the linear (difference in R2 = 0.38; 95% CI, 0.22-0.54; P < .001) and nonlinear (difference in R2 = 0.36; 95% CI, 0.21-0.51; P < .001) regression models.

Conclusions and relevance: In this study, OCT measurement of inner macular thickness shows a higher diagnostic performance to detect glaucoma and a stronger structure-function association than the currently used OCT-A measurement of inner macular vessel density. These findings may suggest that OCT-A of the macula has a limited role in the diagnostic evaluation of glaucoma.

Figure 1.. Comparison of the Regions of Interest for Optical Coherence Tomography Angiography (OCT-A) and OCT Measurements Adopted in Clinical Studies

The OCT-A measurements of vessel density at the macula (3 × 3-mm² [dashed blue lines]; 6 × 6 mm² [solid blue lines]) and OCT measurements of ganglion cell complex (GCC) (Optovue Inc) (orange circle) and ganglion cell inner plexiform layer (GCIPL) thicknesses (orange ellipse) (Carl Zeiss Meditec). The 4 visual field locations (24-2) corresponding to the 3 x 3-mm² central macular region are highlighted in black.

Figure 2.. Example of Optical Coherence Tomography Angiography (OCT-A) and OCT Measurements in a Healthy Eye

The OCT-A images (A), color-coded inner macular vessel density (B) and inner macular thickness (C) maps, and the corresponding visual sensitivity (outlined in red) (D) at the central 3 x 3-mm² macular region. The triangle represents the blind spot.

Figure 3.. Example of Optical Coherence Tomography Angiography (OCT-A) and OCT Measurements in an Eye With Mild Glaucoma (Visual Field Mean Deviation, −4.95 dB)

The OCT-A images (A), color-coded inner macular vessel density (B) and inner macular thickness (C) maps, and the corresponding visual sensitivity (outlined in red) (D) at the central 3 x 3-mm² macular region. The triangle represents the blind spot.

Figure 4.. Example of Optical Coherence Tomography Angiography (OCT-A) and OCT Measurements in an Eye With Advanced Glaucoma (Visual Field Mean Deviation, −32.96 dB)

The OCT-A images (A), color-coded inner macular vessel density (B) and inner macular thickness (C) maps, and the corresponding visual sensitivity (outlined in red) (D), at the central 3 x 3-mm² macular region. The triangle represents the blind spot.