Spending too much time indoors might be the cause of myopia in children, says a new study published in the journal Current Biology.
Myopia affects over a billion people from all over the world, and its incidence is on the rise. Researchers are, therefore, putting in more and more efforts to understand the causes to be able to come up with efficient treatment methods.
The new study, conducted by Northwestern Medicine scientists, sheds light on a growing problem in our contemporary societies: the tendency to spend too much time indoors, thereby keeping one away from natural light. Lead author, Greg Schwartz, and his team focused on the possible effects of this variable on a particular cell in the eye retina; the latter might be causing myopia because of a dysfunction linked with remaining indoors for too long.
“This discovery could lead to a new therapeutic target to control myopia,” says Greg Schwartz.
The growth and development of the eye are processes that need to be kept within limits, and this cell is linked with them.
“The eye needs to stop growing at precisely the right time during childhood,” Schwartz said.
The regulation of eye growth in childhood is dependent on a signal the retina sends to have the image of the objects viewed to be focused. However, if this undergoes malfunction, sight is affected. Scientists have remained in the dark concerning this because they could not pinpoint the retinal cell that would send the signal.
“But for years no one knew what cell carried the signal,” Schwartz said. “We potentially found the key missing link, which is the cell that actually does that task and the neural circuit that enables this important visual function.”
The findings of the new study are, therefore, extremely eye-opening as they entail the discovery of this special retinal cell, named the ON Delayed. Schwartz and his team found that the On Delayed cell is highly sensitive to light—to whether an image is focused or not—to a greater extent than other cells in the eye. Furthermore, the results show that this cell can send instructions to the organ of sight to grow excessively long such that images are not correctly focused on the retina, resulting in near-sighted vision which requires corrective glasses or contact lenses.
The neural circuit in question allows for the new retinal cell to be connected to other cells to cater for its heightened sensitivity. These photoreceptors, located in the human eye, are thought to be activated by high red/green contrast that makes up the indoor light spectrum. The On Delayed cell might be subjected to over-stimulation because of these patterns, resulting in abnormal over-growth of the eye, which then leads to myopia, explains Schwartz.
The team now looks forward to identifying the gene behind this cell so that they can experiment on increasing and decreasing its activity to find out whether myopia can be cured or not.