The developing pre-natal eye requires light that passes through the body and into the womb, according to recent animal research. Mice that had no access to light during pregnancy gave birth to offspring whose eyes were not developed correctly. This indicated that small amounts of light are necessary, during gestation, to control eye blood vessel growth.
This research is considered to be a breakthrough, and scientists were surprised because until now, maternal exposure to light during pregnancy was not considered relevant to fetal development.
In normal fetal eye development, the hyaloid vasculature develops as a network of blood vessels to provide nourishment to the growing retina. When these blood vessels are no longer needed, the body dissolves them. When the baby mice did not get exposed to any light through their mothers, this structure remained in place. If this same effect applies to humans, the time when the structure is removed is most likely during the first trimester.
The research is not trying to simulate real-life scenarios, because it is unlikely that a pregnant human female would spend her entire pregnancy in total darkness. Instead, this research is intended to further understand diseases and disorders of the eye.
Ultimately, blood vessels play a role in eye disease. For example, in wet macular degeneration (choroidal neovascularization), new, abnormal blood vessels develop near the macula and cause rapid, serious vision loss. Low tension glaucoma may indicate poor blood circulation, because the optic nerve is damaged by not receiving sufficient oxygen and nutrients from the blood.
The eye’s blood vessels in premature babies with retinopathy prematurity overgrow abnormally. The child’s retina can be damaged and they can lose vision. The baby mice also had an overgrowth of blood vessels.
This research shows that there is still much to understand about how the eye develops and functions.
Study: “A direct and melanopsin-dependent fetal light response regulates mouse eye development” Rao et. al. Nature (2013) doi:10.1038/nature11823, 16 January 2013