Scientists at Johns Hopkins have cracked a decades-old mystery about how humans develop sharp central vision. Rather than blue cone cells migrating away from the retina's center, they actually transform into red and green cones — driven by vitamin A-derived signals and thyroid hormones. The discovery could pave the way for future cell therapies to restore vision lost to macular degeneration.
Scientists at Johns Hopkins University have upended a 30-year-old theory about how the human eye develops sharp central vision. Using lab-grown retinal tissue (organoids), researchers discovered that blue cone cells in the foveola — the tiny retinal region responsible for about half of all human visual perception — don't migrate away as previously thought. Instead, they transform into red and green cones through a precisely timed two-step process involving vitamin A and thyroid hormones.
The study, published in the Proceedings of the National Academy of Sciences, found that between weeks 10 and 14 of fetal development, retinoic acid (a vitamin A derivative) first suppresses the formation of new blue cones, then thyroid hormones convert the remaining blue cones into red and green ones — the only types found in the foveola.
Key Takeaways:
Why it matters: Macular degeneration, glaucoma, and related diseases rob millions of their central vision with no current cure. This discovery deepens our understanding of retinal development and brings scientists closer to growing transplantable tissue that could one day restore lost sight.
