New Vitamin A Discovery Reshapes Scientists' Understanding of Vision - Video

What if scientists could one day restore lost vision by recreating how the eye develops before birth? A new study has uncovered the biological blueprint behind our sharpest eyesight.

Scientists at Johns Hopkins University have identified how humans develop sharp central vision before birth, revealing a crucial interaction between a vitamin A-derived molecule and thyroid hormones that shapes the retina.

Published in the Proceedings of the National Academy of Sciences (PNAS), the findings challenge a decades-old theory of retinal development and could pave the way for future treatments for macular degeneration, glaucoma, and other vision disorders.

Using lab-grown retinal organoids developed from fetal cells, researchers tracked the formation of the foveola, the tiny central region of the retina responsible for the sharpest vision. Although it occupies only a small part of the retina, the foveola accounts for nearly half of human visual perception.

The study focused on cone photoreceptors, which enable color and daytime vision. Humans have three cone types—blue, green, and red—but the foveola contains only red and green cones. Researchers observed that during weeks 10 to 12 of fetal development, a few blue cones initially appeared in the foveola. By week 14, these cells had transformed into red and green cones.

The team found that this transition occurs through a two-step process. First, levels of retinoic acid, a molecule derived from vitamin A, decline, limiting the formation of new blue cones. Next, thyroid hormones convert the remaining blue cones into red and green cones, creating the specialized arrangement needed for sharp vision.

The findings challenge the long-held belief that blue cones simply migrate away from the foveola during development. Instead, the study suggests they remain in place and change their identity. Researchers believe the discovery could help develop healthier retinal cells for future cell replacement therapies aimed at restoring vision in people with retinal diseases.

REFERENCE: Katarzyna A. Hussey, Kiara C. Eldred, Brian Guy, Clayton P. Santiago, Jingliang Simon Zhang, Ian Glass, Thomas A. Reh, Seth Blackshaw, Loyal A. Goff, Robert J. Johnston. A cell fate specification and transition mechanism for human foveolar cone subtype patterning. Proceedings of the National Academy of Sciences, 2026; 123 (7) DOI: 10.1073/pnas.2510799123