NIH maps living-eye cone cells across age and sex

At the National Eye Institute, researchers are turning images of living eyes into a map of healthy vision. Their new open-source database contains 9,350 verified measurements of cone photoreceptor inner segments—the metabolically active parts of the retinal cells responsible for color vision—across healthy volunteers aged 12 to 84.

The project fills a gap that has made retinal diagnosis harder: doctors have not had a large public reference showing how healthy cones vary with age, sex and retinal location. Diseases such as retinitis pigmentosa, Usher syndrome and choroideremia can alter cone size and shape, but the same measurements can also reflect ordinary aging or natural variation between people.

To build the map, Johnny Tam and his team used adaptive optics to correct distortions in light as it travels through the eye, allowing them to resolve individual cones. An artificial intelligence algorithm traced each cell; experts then checked the outlines, removed poorly defined cells and added cells the system had missed until the results were agreed by independent reviewers.

The pattern was not uniform across the retina. Cones were smallest near the fovea, the central region needed for sharp vision, and became larger with increasing distance from it. Women's cones were, on average, about 5% larger than men's, while cones gradually shrank with advancing age, with the clearest shrinkage at moderate distances from the fovea.

So what changes in practice? The database gives clinicians and researchers a healthy reference against which to compare a patient's cells, potentially helping them distinguish early disease-related damage from typical aging and follow whether new treatments are working at the cellular level. The figures describe a reference dataset, not a clinical treatment result; the team still plans to add more retinal areas and examine conditions including retinitis pigmentosa, choroideremia and Stargardt disease.