Sure, growing eyeballs in a petri dish makes for a good Halloween story, but can they also help solve the problem of color blindness?

The development of color vision is difficult to study because it occurs while we’re still in the womb. But scientists at Johns Hopkins University thought they might find answers using retinas grown in the lab. Retinal organoids have been around for a while but it takes about a year to turn immature retinal cells into a functioning organoid.

The scientists knew from previous research that in a human fetus, cells that detect blue light appear first, and then the cells that respond to red and green light develop. And they knew that the thyroid hormone was involved in the development of these color-sensing cells, or cones. By adding thyroid hormone to the dish during their development of the retinal organoids, they got more red-green cones to develop.

The Cone Mystery

The team still doesn’t understand why some cones become even more specialized by detecting only red or only green. But, they’ve already made plans to expand the research into restore color vision to patients with gene therapy. They’re also planning to use the retinal organoids to better understand diseases like glaucoma and macular degeneration.

Science Magazine published the study. And as a bonus the National Eye Institute is sponsoring a scientific competition with $1 million in prizes to encourage scientists to develop more retinal organoids for research.