Code from: The retinal age gap: An affordable and highly accessible biomarker for population-wide disease screening across the globe

Traditional biomarkers, such as those obtained from blood tests, are
essential for early disease detection, improving health outcomes, and
reducing healthcare costs. However, they often involve invasive
procedures, specialized laboratory equipment, or special handling of
biospecimens. The retinal age gap (RAG) has emerged as a promising new
biomarker that can overcome these limitations, making it particularly
suitable for disease screening in low- and middle-income countries. This
study aimed to evaluate the potential of the RAG as a biomarker for broad
disease screening across a vast spectrum of diseases. Fundus images were
collected from 86,522 UK Biobank participants, aged 40 to 83 (mean age:
56.2±8.3 years). A deep learning model was trained to predict retinal age
using 17,791 images from healthy participants. The remaining images were
categorized into disease/injury groups based on clinical codes.
Additionally, 8,524 participants from the Brazilian Multilabel
Ophthalmological Dataset (BRSET) were used for external validation. Among
the 159 disease/injury groups from the 2019 Global Burden of Disease
Study, 56 groups (35.2%) exhibited RAG distributions significantly
different from healthy controls. Notable examples included chronic kidney
disease, cardiovascular disease, blindness, vision loss, and diabetes.
Overall, the RAG shows great promise as a cost-effective, non-invasive
biomarker for early disease screening.