Quantitative ophthalmic posterior segment optical coherence tomography angiography and neurologic conditions: a review

Objectives: To investigate the potential of quantitative ophthalmic posterior segment optical coherence tomography angiography (OCTA) imaging metrics to serve as biomarkers for systemic involvement in five neurologic diseases (multiple sclerosis, neuromyelitis optica spectrum disorder, myelin oligodendrocyte glycoprotein antibody-associated disease, Alzheimer disease, and Parkinson disease) by reviewing the reported correlations between such OCTA metrics and clinically relevant features of systemic involvement in these diseases. Methods: This article is a literature review of the PubMed database for articles reporting OCTA metrics in any of the included neurologic diseases. Articles correlating quantitative retinal, optic nerve head, or choriocapillaris OCTA metrics to clinically relevant features of systemic involvement, specifically serum, cerebrospinal fluid (CSF), or other established biomarkers; genotype; systemic symptom and severity scores; stage; non-ocular organ involvement; brain or other non-ocular imaging findings; and systemic medication use were included. Results: OCTA parameters have been significantly correlated to established biomarkers, severity scores, non-ocular organ involvement and imaging findings, and systemic medication use in multiple sclerosis. OCTA parameters have been significantly correlated to established biomarkers, severity scores, and non-ocular organ involvement and imaging findings in neuromyelitis optica spectrum disorder. OCTA parameters have been significantly correlated to severity scores in myelin oligodendrocyte glycoprotein antibody-associated disease. OCTA parameters have been significantly correlated to established biomarkers, genotype, severity scores, disease stage, and non-ocular organ involvement and imaging findings in Alzheimer disease. OCTA parameters have been significantly correlated to severity scores, disease stage, and non-ocular organ involvement in Parkinson disease. Conclusion: Our findings suggest that ophthalmic posterior segment OCTA might improve our understanding of the pathophysiology of systemic neurologic conditions, including those that do not traditionally affect the eye, and might identify biomarkers useful in the diagnosis, prognosis, and management of these conditions, justifying further investigation.