OCT-angiography: Regional reduced macula microcirculation in ocular hypertensive and pre-perimetric glaucoma patients

Abstract

Purpose: OCT-angiography (OCT-A) offers a non-invasive method to visualize retinochoroidal microvasculature. As glaucoma disease affects retinal ganglion cells in the macula, macular microcirculation is of interest. The purpose of the study was to investigate regional macular vascular characteristics in patients with ocular hypertension (OHT), pre-perimetric primary open-angle glaucoma (pre-POAG) and controls by OCT-A in three microvascular layers.

Material and methods: 180 subjects were recruited from the Erlangen Glaucoma Registry, the Department of Ophthalmology, University of Erlangen and residents: 38 OHT, 20 pre-POAG, 122 controls. All subjects received an ophthalmological examination including measurements of retinal nerve fibre layer (RNFL), retinal ganglion cell layer (RGC), inner nuclear layer (INL), and Bruch's Membrane Opening-Minimum Rim Width (BMO-MRW). Macular vascular characteristics (vessel density, VD, foveal avascular zone, FAZ) were measured by OCT-A (Spectralis OCT II) in superficial vascular plexus (SVP), intermediate capillary plexus (ICP), and deep capillary plexus (DCP).

Results: With age correction of VD data, type 3 tests on fixed effects showed a significant interaction between diagnosis and sectorial VD in SVP (p = 0.0004), ICP (p = 0.0073), and DCP (p = 0.0003). Moreover, a significance in sectorial VD was observed within each layer (p<0.0001) and for the covariate age (p<0.0001). FAZ differed significantly between patients' groups only in ICP (p = 0.03), not in SVP and DCP. For VD the AUC values of SVP, ICP, and DCP were highest among diagnostic modalities (AUC: 0.88, 95%-CI: 0.75-1.0, p<0.001).

Conclusion: Regional reduced macula VD was observed in all three retinal vascular layers of eyes with OHT and pre-POAG compared to controls, indicating localized microvascular changes as early marker in glaucoma pathogenesis.

Trial registration: ClinicalTrials.gov NCT00494923.

Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1. Segmentation of en face OCTA’s superficial vascular plexus (SVP), intermediate capillary plexus (ICP), deep capillary plexus (DCP) in correlation to structure OCT layers’ ganglion cell layer (GCL), inner plexiform layer (IPL) and inner nuclear layer (INL) and outer plexiform layer (OPL).

Fig 2. Analysis of covariance for BMO-MRW (a), RNFL (inner, b; middle, c; outer, d), and GCL (e) considering age and patients’ groups.

(a) a significant age effect on BMO-MRW was observed (p = 0.047); (b-d) age showed an impact on RFNL for the inner and middle scan; gender was significantly associated with RNFL of the outer scan; (e) a significant decrease of RGC was observed with increasing age for male and female persons (p = 0.0021).

Fig 3. Qualitative analysis of the number of significant interactions between vessel density of each sector (s1-s12) of macula OCT-A in SVP, ICP, and DCP by color coding (red, n = 8–12; pink, n = 6–7; orange, n = 5; yellow, n = 4; green, n = 2–3; grey, n = 0–1) in controls, OHT, and pre-OAG eyes, respectively (a) and between the groups (b) with age correction of the data: Notice the temporal emphasis in SVP and the nasal emphasis in DCP.

Fig 4. Analysis of covariance for FAZ of ICP across age subdivided for gender and diagnosis (OHT, pre-OAG, controls).

Fig 5. Receiver operating curves (ROC) of mean (a) and sectorial (b-d) vessel density in SVP, ICP, and DCP for differentiation between patients’ group and controls.