Alterations in the Retinal Vascular Network and Structure in Myelin Oligodendrocyte Glycoprotein Antibody-Associated Optic Neuritis: A Longitudinal OCTA Study

Optical coherence tomography angiography measurements in neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein antibody disease: A systematic review and meta-analysis

PURPOSE

Neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody disease (MOGAD) are immune-mediated disorders that can often manifest with optic neuritis (ON) among other symptoms. Optical coherence tomography angiography (OCTA) is an emerging diagnostic method that can quantify retinal capillary blood flow and vessel density (VD), which have been shown to be affected in NMOSD and MOGAD. Hence, we aimed to systematically review the studies addressing retinal microvasculature using OCTA in these diseases.

DESIGN

Systematic review and meta-analysis.

METHODS

PubMed, EMBASE, and Web of Sciences were systematically searched to identify articles addressing OCTA measurements in patients with NMOSD or MOGAD. Following the data extraction, a meta-analysis was performed on the study population and OCTA types amongst at least two homogenous studies.

RESULTS

Twenty-two studies on NMOSD, MOGAD, or both were included. Parafoveal superficial retinal capillary plexus (SRCP) VD and radial peripapillary capillary (RPC) VD were diminished in NMOSD ON+ and NMOSD ON- groups compared to healthy controls (HCs). In addition, both the SRCP VD and RPC VD were significantly reduced in NMOSD ON+ compared to NMOSD ON-. However, meta-analysis for deep retinal capillary plexus (DRCP) did not show a significant difference between NMOSD patients and HCs, or among ON+ and ON- patients. Furthermore, there was no significant difference in foveal avascular zone (FAZ) area size between NMOSD patients and HCs. Regarding MOGAD, the meta-analysis showed decreased parafoveal SRCP VD and RPC VD in MOGAD ON+ patients compared to HCs. Comparing NMOSD ON+ and MOGAD ON+, a meta-analysis was conducted for RPC VD, which showed no significant difference between the two groups.

CONCLUSIONS

This systematic review and meta-analysis confirmed reduced VD in the macular and peripapillary areas in NMOSD and MOGAD eyes, particularly in the parafoveal SRCP and RPC, which is further impacted by prior ON.

Oxidative Stress in Optic Neuropathies

Increasing evidence indicates that changes in the redox system may contribute to the pathogenesis of multiple optic neuropathies. Optic neuropathies are characterized by the neurodegeneration of the inner-most retinal neurons, the retinal ganglion cells (RGCs), and their axons, which form the optic nerve. Often, optic neuropathies are asymptomatic until advanced stages, when visual impairment or blindness is unavoidable despite existing treatments. In this review, we describe systemic and, whenever possible, ocular redox dysregulations observed in patients with glaucoma, ischemic optic neuropathy, optic neuritis, hereditary optic neuropathies (i.e., Leber's hereditary optic neuropathy and autosomal dominant optic atrophy), nutritional and toxic optic neuropathies, and optic disc drusen. We discuss aspects related to anti/oxidative stress biomarkers that need further investigation and features related to study design that should be optimized to generate more valuable and comparable results. Understanding the role of oxidative stress in optic neuropathies can serve to develop therapeutic strategies directed at the redox system to arrest the neurodegenerative processes in the retina and RGCs and ultimately prevent vision loss.