OCT Angiography of the Central Macular Capillary Network in Glaucoma Patients and Healthy Controls

We aimed to investigate central macular microvasculature by optical coherence tomography angiography (OCTA) and to analyse its relation to alterations in classical parameters of optical coherence tomography (OCT) in glaucoma patients.

Using OCTA (Avanti incl. AngioVue; Optovue, Inc., Fremont, CA), the superficial flow (SF) and the superficial non-flow (SNF) area of the macula, as well as the S-ETDRS (based on Early Treatment Diabetic Retinopathy charts). and S-grid vessel density (zones 1 - 9) of the macula, were evaluated in 27 glaucoma patients (49 eyes) and compared to those of 27 age-matched healthy controls (50 eyes; p = 0.253). The interactions between OCTA parameters representing macular microvasculature and classical OCT measurements of the circumpapillary retinal nerve fibre layer (RNFL) and macular ganglion cells (mGCC) were analysed within groups (linear mixed-effects model).

SF, SNF, and S-ETDRS vessel density exhibited no significant difference between the glaucoma and control groups (all p ≥ 0.158). However, within the glaucoma group, decreased RNFL and mGCC thickness correlated significantly with decreased S-ETDRS density (zones 1; 2 - 9, p ≤ 0.033). The same held true for the interactions between the RNFL and mGCC thickness with S-grid density (zones 1 - 3; 6 - 9; p ≤ 0.033). For perimetric glaucoma patients, subgroup analyses demonstrated significantly reduced density maps of superficial foveal flow as well as significant interactions between OCT and OCTA parameters; this was not the case within the preperimetric group.

Even if the central macular microvasculature, as measured by SF and SNF, is found preserved in glaucoma, the strong positive relation between the central microvascular and structural changes in OCTA and OCT indicates that there are alterations in central macular microvasculature in subclinical glaucoma.