Retinal optical coherence tomography biomarkers in dementia

Abstract

Due to the general aging of society, the prevalence and incidence of dementia are expected to increase considerably. In order to timely identify patients and assess their need for treatment and/or supportive measures, comprehensive and easy access screening methods are required, which, however, are yet to be developed. To date, several biomarkers for the presence of dementia on high-resolution spectral domain optical coherence tomography (OCT) and OCT angiography (OCT-A) images were identified. To summarize previously identified OCT biomarkers in dementia and to assess their suitability for comprehensive screening examinations. Aliterature search was conducted on PubMed until March 2023 for the keywords "dementia", "mild cognitive impairment", "OCT", "OCT angiography" and "retinal biomarkers". Relevant publications were identified and summarized. Numerous unspecific alterations on OCT imaging and OCT‑A were identified in patients with (predementia) dementia according to many population and clinical studies. These include areduced thickness of the peripapillary retinal nerve fiber layer, the ganglion cell complex and the central retinal region. Additionally, areduced vascular density and an enlarged foveal avascular zone (FAZ) were identified on OCT‑A imaging. The currently known OCT biomarkers are too unspecific, and there is to date no OCT or OCT-A-based signature distinguishing between different types of dementia. Further longitudinal studies with larger sample sizes are warranted to develop and evaluate such distinct OCT signatures for different types of dementia and their respective early disease stages and to assess their prognostic value. Only then is the inclusion in comprehensive screening investigations feasible.