Age-related macular degeneration is the most common cause of severe vision loss among people over the age of 50.
According to previous research, smokers are four times more likely to develop the disease.
A new study from Johns Hopkins Medicine, published in PNAS, has examined what specifically happens in the eye.
The researchers focused on particular cells in the retina known as RPE cells. These cells are essential for protecting the light-sensitive cells that make clear vision possible.
Also read: Ten years of data link wildfire smoke to increased urban violence
The results show that cigarette smoke alters the way the cells’ genes function.
This occurs without changing the genetic material itself, but by switching genes on and off differently than normal.
Difference between young and old
The researchers also conducted experiments on mice in two age groups. Both groups experienced damage to their RPE cells after being exposed to smoke.
However, there was an important difference. In the young mice, a number of protective genes were activated in the damaged cells. This did not happen to the same extent in the older mice.
Also read: New analysis suggests consciousness may continue after death
According to the study, this may mean that younger cells are temporarily better able to defend themselves against damage from smoke, while older cells have greater difficulty coping with the strain.
The same pattern in humans
The researchers also examined eye cells from humans, both smokers and non-smokers. They identified 1,698 genes that changed in the same way in both mice and humans.
Smoking may directly affect the cells of the eye and contribute to the onset or worsening of macular degeneration.
Also read: How daily olive oil intake affects the body
Also read: High red meat intake associated with 49 percent increase in diabetes risk