New research in Nature concludes the eye, which depends on light to see, also needs light to develop normally during pregnancy.

Baby Eye DevelopmentScientists say the unexpected finding offers a new basic understanding of fetal eye development and ocular diseases caused by vascular disorders — in particular one called retinopathy of prematurity that can blind premature infants.

This fundamentally changes our understanding of how the retina develops,”

says study co-author Richard Lang, PhD, a researcher in the Division of Pediatric Ophthalmology at Cincinnati Children’s Hospital Medical Center. “We have identified a light-response pathway that controls the number of retinal neurons. This has downstream effects on developing vasculature in the eye and is important because several major eye diseases are vascular diseases.”

Lang is a principal investigator on the ongoing research along with project collaborator, David Copenhagen, PhD, a scientist in the departments of Ophthalmology and Physiology at UCSF. The scientists say their current study, conducted in mouse models, includes several unexpected findings.
“Several stages of mouse eye development occur after birth,” says Copenhagen. “Because of this, we had always assumed that if light played a role in the development of the eye, it would also happen only after birth.”

But researchers in the current study found that activation of the newly described light-response pathway must happen during pregnancy to activate the carefully choreographed program that produces a healthy eye. Specifically, they say it is important for a sufficient number of photons to enter the mother’s body by late gestation.

Researchers were also surprised to learn that photons of light activate a protein called melanopsin directly in the fetus — not the mother — to help initiate normal development of blood vessels and retinal neurons in the eye.

One purpose of the light-response pathway is to suppress the number of blood vessels that form in the retina. These vessels are critical to retinal neurons, which require large amounts of oxygen to form and to function. When retinopathy of prematurity occurs in infants, retinal vessels grow almost unchecked. This continued expansion puts intense pressure on the developing eye and in extreme cases causes severe damage and blindness.

Lang said the research team is continuing to study how the light-response pathway might influence the susceptibility of pre-term infants to retinopathy of prematurity and also be related to other diseases of the eye.