Abstract
The aim of this study was to perform quantitative optical coherence tomography angiography (OCTA) assessment of arteritic and non-arteritic anterior ischemic optic neuropathies (AION; NAION). The study was designed as an observational, cross-sectional case series. All patients underwent complete ophthalmologic evaluation including LogMAR best-corrected visual acuity (BCVA), structural optical coherence tomography (OCT) and OCTA images, and dye-based angiography. Retinal nerve fiber layer (RNFL) thickness was obtained from structural OCT, and vessel density (VD) and vessel tortuosity (VT) were measured for each optic nerve head vascular plexus. After selecting the quadrants showing visual field defects, measured by Humphrey 30.2 perimetry (Zeiss Meditec, Dublin, CA, USA), we assessed the correlation between the localization of visual field defects and the quadrants showing impairments of RNFL, VD, and VT. Thirty naïve AION patients (15 arteritic AION (AAION) and 15 non-arteritic AION (NAION)) were included. LogMAR BCVA was 0.6 ± 0.2 for AAION and 0.3 ± 0.3 for NAION (p < 0.01). AAION and NAION eyes showed significant differences in terms of visual field involvement as well as VD and VT values, with remarkably worse alterations affecting AAION eyes. VD values perfectly matched with the quadrants showing RNFL and visual field defects. On the contrary, VT resulted remarkably decreased in all the quadrants, with even worse values in the quadrants showing RNFL and visual field alterations. The present study showed that AAION eyes are more injured than NAION ones. VD represents a good parameter for the detection of the main site on vascular impairment. Remarkably, VT resulted in a more sensitive parameter for the quantitative detection of blood flow impairment in AION disease.
Highlights
Anterior ischemic optic neuropathies (AION) represents a set of diseases affecting the anterior portion of the optic nerve, distinguished as arteritic (AAION) and non-arteritic (NAION) [1]
Moving beyond the starting factor leading to the onset of the disease, both NAION and AAION are characterized by the concomitant presence of optic nerve ischemia and inflammation, both contributing to the onset and progression of typical symptoms, such as visual acuity reduction and visual field defects [2]
Whereas clinical presentation is often worse than the final outcome due to the resolution of the acute optic nerve edema, AION leads to permanent visual field defects [1]
Summary
Anterior ischemic optic neuropathies (AION) represents a set of diseases affecting the anterior portion of the optic nerve, distinguished as arteritic (AAION) and non-arteritic (NAION) [1]. Moving beyond the starting factor leading to the onset of the disease, both NAION and AAION are characterized by the concomitant presence of optic nerve ischemia and inflammation, both contributing to the onset and progression of typical symptoms, such as visual acuity reduction and visual field defects [2]. The diagnostic workup of AION benefits from the combined use of fluorescein angiography (FA) and non-invasive multimodal imaging [2]. In this context, structural optical coherence tomography (OCT) and OCT angiography (OCTA) provided very detailed information regarding the structural and vascular impairment of the optic nerve [3,4]. It is worth noting that the adoption of OCTA technology allows one to study microstructural features of the retinal vascular network without the adoption of dye, and with enhanced resolution of smaller retinal vessels
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