CHICAGO (CBS) — Millions of people with diabetes live with the dread of eventually losing their eyesight to the disease. A  California researcher has developed a glowing contact lens he believes could help millions of patients keep their vision longer.

“The small blood vessels that feed the retina begin to die off as a result of the diabetes and so the retina starts to starve from lack of oxygen,” said Colin Cook, the contact developer.

The glowing contact lenses were designed to treat diabetic retinopathy, a condition that causes blindness in diabetics.

Doctors say diabetic retinopathy progresses the most overnight because eyes burn more oxygen in the dark than in the light.

Cook designed his lenses to wear while sleeping, emitting just enough of a glow for the retina to detect “to trick the eye into thinking it’s daytime so the cells aren’t consuming so much oxygen. That helps preserve the cells and the patient’s eyesight.”

Cook says his lenses offer an alternative to painful, existing treatments for diabetic retinopathy, which include injections in the eye.

While the contacts can maintain their glow up to 12 years, he foresees temporary pairs for users.

“Probably about a year and then get a new pair of lenses,” he said, saying he believes his invention could help maintain a user’s vision for years.

Cook says because the contact is so close to the retina and moves with the eye, the glow essentially goes unnoticed by the brain, allowing users to sleep, despite the light. He hopes to start testing the lenses in a clinical trial soon.