# Retinal OCT / fundus imaging

Optical coherence tomography (OCT) takes ultra-detailed cross-section images of your retina, down to the micrometer. It lets doctors measure the thickness of retinal layers, like the macula, the retinal nerve fiber layer (RNFL), and the ganglion cell layer. Fundus photography, meanwhile, captures the retina's blood vessels and optic disc. Here is why the eye is so useful: your retina shares its embryonic origin and blood-vessel design with your brain. So retinal measures act as a window onto your brain and whole-body vascular health. RNFL thinning is an established sign of glaucoma, and it has also been linked to Alzheimer's, multiple sclerosis, and Parkinson's. Deep-learning tools can even estimate cardiovascular risk factors (age, sex, blood pressure, HbA1c) straight from a fundus photo. And new 'retinal age gap' AI clocks predict death and disease beyond your calendar age in big studies. A version called OCT angiography (OCTA) maps blood flow down to the capillaries without any dye.

## Sources

- Pandya BU, Grinton M, Mandelcorn ED, Felfeli T. (2024). Retinal Optical Coherence Tomography Imaging Biomarkers: A Review of the Literature. Retina. https://doi.org/10.1097/IAE.0000000000003974
- Poplin R, Varadarajan AV, Blumer K, Liu Y, McConnell MV, Corrado GS, Peng L, Webster DR. (2018). Prediction of cardiovascular risk factors from retinal fundus photographs via deep learning. Nature Biomedical Engineering. https://doi.org/10.1038/s41551-018-0195-0
- Zhu Z, Shi D, Guankai P, Tan Z, Shang X, Hu W, Liao H, Zhang X, Huang Y, Yu H, et al.. (2023). Retinal age gap as a predictive biomarker for mortality risk. British Journal of Ophthalmology. https://doi.org/10.1136/bjophthalmol-2021-319807

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_Canonical: https://longevity-switzerland.com/en/glossary/retinal-oct · Part of Longevity Cities · Updated 2026-06-22_