A Mouse Eye Learned to Photosynthesize

A team in Singapore gave a mouse's eye the ability to photosynthesize. They used spinach. It worked better than the leading prescription drug for dry eye.

Here's what's actually happening. Dry eye disease is driven by a vicious inflammation cycle. Reactive oxygen species, chemically aggressive molecules, build up in the cornea and overwhelm the eye's natural defenses. The eye needs a molecule called NADPH to neutralize the harmful molecules, but inflamed eyes can't produce enough.

The inspiration for the whole project was a sea slug. Sacoglossan sea slugs steal chloroplasts from microalgae and store them in intestinal cells; when starved, they can live off the photosynthesis those chloroplasts perform, the only known case of an animal pulling this off.

The NUS team's fix amounts to this: extract the thylakoid grana from spinach, the structures where plants convert light into NADPH, package it into tiny particles and drop it into the eye. The thylakoid structures get absorbed by corneal cells and set to work harvesting ambient light to produce NADPH on demand.

In preclinical trials, the treatment reversed corneal damage to near-healthy levels in five days. Restasis, the drug millions of people use for this condition, did not keep up.

The researchers call the process "limited photosynthesis" because the particles don't complete the full plant cycle. They don't produce glucose. But they harvest light and run a biological reaction inside an animal cell.

Clinical trials are next. The team is already eyeing the retina, skin and skeletal muscle as future targets.

Read the full story at NUS News, May 16, 2026

Hot Take: Spinach photosynthesis running inside a corneal cell is either the future of eye medicine or a new reason for your eyes to slam shut in the presence of eye drops. Feed me, Seymour. My corneas are inflamed.