A new study could aid understanding of why some people with eye disease, migraine headaches and concussions experience light sensitivity.
The research, which is published in Proceedings of the National Academy of Sciences, suggests that melanopsin plays a role in photophobia.
Melanopsin is a blue-light sensitive protein in the eye that helps to establish circadian rhythms and restricts the pupil in response to bright light.
Researchers measured the pupil response and brain activity when they shone a pulse of light that stimulates melanopsin cells into the eyes of study participants.
They found that the visual pathway of the brain responded to the melanopsin stimulus. This is significant because the light used in the study only stimulates melanopsin cells and is invisible to the parts of the eye that are normally used for seeing.
Study participants also reported that the pulse of light was unpleasant.
“Our results have clinical importance as melanopsin function may contribute to the discomfort that some people experience from bright light,” the authors concluded.