Abstract
Purpose :
Agonistic β2-adrenergic receptor autoantibodies (β2-AAb) were detected in primary open-angle glaucoma (POAG) and ocular hypertension patients, targeting β2-receptors on ciliary body, trabecular meshwork and pericytes. Next to a potential influence of β2-AAb on intraocular pressure, retinal microcirculation might be influenced by these β2-AAb. It was the aim of the study to investigate foveal avascular zone (FAZ) characteristics by en face OCT angiography (OCT-A) in glaucoma patients considering β2-AAb seropositivity.
Methods :
20 glaucoma patients (8 male, 12 female,) were recruited from the Erlangen Glaucoma Registry (ISSN 2191-5008, CS-2011; NTC00494923). All patients got an ophthalmological examination including Octopus G1 perimetry (mean defect MD, loss variance LV), measuring of retinal nerve fibre layer (RNF), BMO-MRW, retinal ganglion cell layer (RGC) and inner nuclear layer (INL). FAZ characteristics were measured by en face OCT-A scans including superficial vascular plexus (SVP), and intermediate vascular plexus (IVP), and deep capillary plexus (DCP; Spectralis OCT II, Heidelberg, Germany). FAZ-to-FAZ-ratio (FAZ-R) between SVP and IVP were calculated. Serum samples were analysed regarding β2-AAb using a bioassay (cut-off <2.0 beat/15 s). Study was approved by the local ethics committee.
Results :
(I) 88% of all glaucoma patients showed a β2-AAb seropositivity (4.8±1 beats/15 s); 12% of glaucoma patients were β2-AAb seronegative (<2.0 beat/15 s). (II) β2-AAb seropositive glaucoma patients showed no correlation of β2-AAb beat rate with MD, LV, RNF, BMO-MRW, RGC, and INL thickness (p>0.05). (III) FAZ-R showed a mean of 1.38±0.2 in all patients. Subgroup analysis yielded a mean FAZ-R of 1.3±0.2 in β2-AAb seropositive and 1.6±0.1 in β2-AAb seronegative glaucoma patients. (IV) FAZ-R was significantly reduced in β2-AAb seropositive glaucoma patients compared to β2-AAb seronegative patients (p=0.043). (VI) A significant correlation of FAZ-R with β2-AAb beat rate was observed (p=0.002, Pearson’s correlation coefficient -0.690).
Conclusions :
The data of this pilot study might suggest a potential role of β2-AAb on macular microcirculation. As level of β2-AAb did not correlate with standard glaucoma morphometric biomarkers, although FAZ characteristics were significantly different, β2-AAb might be a novel risk factor of glaucoma.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.