Ageing Biomarkers Derived From Retinal Imaging: A Scoping Review

Background/AimsThe emerging concept of retinal age, a biomarker derived from retinal images, holds promise in estimating biological age. The retinal age gap (RAG) represents the difference between retinal age and chronological age which serves as an indicator of deviations from normal ageing. This scoping review aims to collate studies on retinal age to determine its potential clinical utility and to identify knowledge gaps for future research. MethodsUsing the PRISMA checklist, eligible non-review, human studies were identified, selected, and appraised. Pubmed, Scopus, SciELO, PsycINFO, Google Scholar, Cochrane, CINAHL, Africa Wide EBSCO, MedRxiv, and BioRxiv databases were searched to identify literature pertaining to retinal age, the RAG, and their associations. No restrictions were imposed on publication date. ResultsThirteen articles published between 2022 and 2023 were analysed, revealing four models capable of determining biological age from retinal images. Three models, Retinal Age, EyeAge and a convolutional network-based model, achieved comparable mean absolute errors (MAE): 3.55, 3.30 and 3.97 respectively. A fourth model, RetiAGE, predicting the probability of being older than 65 years, also demonstrated strong predictive ability with respect to clinical outcomes. In the models identified, a higher predicted RAG demonstrated an association with negative occurrences, notably mortality and cardiovascular health outcomes. ConclusionThis review highlights the potential clinical application of retinal age and RAG, emphasising the need for further research to establish their generalisability for clinical use, particularly in neuropsychiatry. The identified models showcase promising accuracy in estimating biological age, suggesting its viability for evaluating health status. Key MessageO_ST_ABSWhat is already known on this topicC_ST_ABSRetinal age has emerged as a promising ageing biomarker capable of determining biological age from retinal images. What this study addsThis study presents a comprehensive scoping review of current literature concerning retinal age and the RAG, highlighting the reproducible association between advanced retinal age gap and increased mortality and cardiovascular disease risk. How this study might affect research, practice, or policyThe findings underscore the paucity of knowledge on this topic, advocating for further research in this area to determine the potential clinical use of retinal age as a biomarker. SynopsisThis scoping review explores retinal age, a biological ageing marker derived from retinal images. Findings from 13 articles reveal links between advanced retinal ageing gaps and adverse outcomes, emphasizing its potential for improving health outcomes.