Progressive Macula Vessel Density Loss in Primary Open-Angle Glaucoma: A Longitudinal Study

Abstract

Purpose: To characterize the rate of macula vessel density loss in primary open-angle glaucoma (POAG), glaucoma-suspect, and healthy eyes.

Design: Longitudinal, observational cohort from the Diagnostic Innovations in Glaucoma Study.

Methods: One hundred eyes (32 POAG, 30 glaucoma-suspect, and 38 healthy) followed for at least 1 year with optical coherence tomography angiography (OCT-A) imaging on at least 2 visits were included. Vessel density was calculated in the macula superficial layer. The rate of change was compared across diagnostic groups using a multivariate linear mixed-effects model.

Results: Baseline macula vessel density was highest in healthy eyes, followed by glaucoma-suspect and POAG eyes (P < .01). The rate of vessel density loss was significantly different from zero in the POAG, but not in the glaucoma-suspect or healthy eyes. The mean rate of change in macula whole en face vessel density was significantly faster in glaucoma eyes (-2.23%/y) than in glaucoma-suspect (0.87%/y, P = .001) or healthy eyes (0.29%/y, P = .004). Conversely, the rate of change in ganglion cell complex (GCC) thickness was not significantly different from zero in any diagnostic group, and no significant differences in the rate of GCC change among diagnostic groups were found.

Conclusions: With a mean follow-up of less than 14 months, eyes with POAG had significantly faster loss of macula vessel density than either glaucoma-suspect or healthy eyes. Serial OCT-A measurements also detected glaucomatous change in macula vessel density in eyes without evidence of change in GCC thickness.

Copyright © 2017 Elsevier Inc. All rights reserved.

Figures

Figure 1

A spectral domain optical coherence tomography angiography (OCT-A) 3 × 3 scan of the macula showing the superficial vascular plexus. The AngioVue software automatically defined a 3.0 mm × 3.0 mm square area as the whole en-face region (A), which was divided into 2 regions (white dotted line) into the superior and inferior en-face area. Moreover, a central (inner pink) circle was defined as the fovea (B), and the parafoveal region was defined as a ring surrounding the foveal region (C–F). The parafoveal region was also divided into 4 sectors of 90°, viz., as para-temporal (C), superior (D), nasal (E), and inferior (F).

Figure 2

Longitudinal changes in optical coherence tomography angiography images of the superficial retinal vascular plexus (3.0 mm × 3.0 mm scan size) in a healthy and in a glaucomatous eye. Top and fifth row: fundus photograph (left) and vessel density map, seen over time in healthy subject using optical coherence tomography (OCT) -angiography(A). Second and sixth row: standard automated perimetry (SAP) results (left) and area density color-coded map in a healthy subject (2nd row) and glaucoma patients (6th row). OCT-A macula scan showing the superficial vascular plexus; corresponding color-coded flow density map of the superficial vascular plexus flow density (the warmer the color, the greater the flow). This healthy case shows vessel density was almost unchanged (56.23% to 57.38%) over time. In contrast, vessel density was decreased 50.06% to 44.38% overtime, regardless of SSI in glaucoma patients. Third and seventh row: ganglion cell complex (GCC) map over time. The measurement parameters from GCC thickness of analysis are automatically compared to the OCT’s normative limits, and the results are color-coded for “within normal limits” (green), “borderline” (yellow), and “outside normal limits” (red). The average GCC thickness was also almost unchanged over time both healthy subjects (104.7μm to 105.5μm) and glaucoma patients (59.4μm to 60.5μm). Fourth and bottom row: optic nerve head (ONH) thickness color-coded map (the warmer the color, the greater the thickness) and results of sector analysis automatically compared to the OCT’s normative limits, color-coded for “within normal limits” (green), “borderline” (yellow), and “outside normal limits” (red) at outer ring. The average cpRNFL thickness was also almost unchanged over time in both cases.

Figure 3

Boxplots illustrating the distribution of the rate of vessel density change (%/year) in whole en-face vessel density (top), superior en-face vessel density (middle), and inferior en-face vessel density (bottom) measurements in healthy, glaucoma-suspects, and glaucomatous eyes. The medians are represented by horizontal lines in the white boxes. Boxes represent the interquartile range (IQR) between the first and third quartiles.