Biological clock pigment could help blind people
Light sensing cells (photosensitive ganglion cells) in the eye, which contain the pigment melanopsin, set the body's biological clock. They also play an important role in our perception of brightness, according to recent research in mice.
Treatments for blindness could result from modifying the cells that contain melanopsin.
Researchers used mice to trace melanopsin messenger cells from the eye into the brain. They found they extended all the way to the brain's visual processing centre. This suggests that melanopsin may play a role in our perception of light.
To test this further, researchers then exposed mice lacking rods and cones to light. Even though these mice were technically blind, they still showed activity in the 'sight-region' of the brain.
Until now melanopsin's main function was thought to be that of regulating our biological clock. By detecting changes in ambient light levels throughout the day, melanopsin synchronises the body's daily rhythms. This process is subconscious, but the newly discovered function of melanopsin affects conscious visual perception - the experience of sight.
A common cause of blindness in humans is the loss of rods and cones. Despite this, these people are still able to perceive some light. It was previously thought this was because the loss of road and cones was incomplete. However, the new research suggests this is could be due to melanopsin containing cells.
As melanopsin containing cells are not normally destroyed with rods and cones, it is hoped that they could be used to treat blindness. Melanopsin cells have worse resolution than rods and cones and so only forms a blurry picture of our surroundings. Researchers hope to engineer melanopsin to be produced in a greater number of cells. This may increase resolution and so be used to improve the sight of blind people.
Find out more about blindness here.