Smoking is widely known to harm the lungs and heart, but scientists are now learning much more about how it can also damage the eyes. One of the most serious eye diseases linked to smoking is age-related macular degeneration, often called AMD.
This condition is the leading cause of severe vision loss and blindness among people over the age of 50 worldwide. AMD affects the macula, a small but important area in the center of the retina that allows people to see fine details, read, recognize faces, and drive. When the macula is damaged, central vision becomes blurry or disappears completely.
For years, doctors have observed that smokers are about four times more likely to develop AMD than people who never smoked. However, exactly how cigarette smoke causes this damage has remained unclear.
Now, researchers at Johns Hopkins Medicine, supported by the National Institutes of Health, have uncovered new clues about what smoking does inside the eye at the cellular level.
The team focused on special cells called retinal pigment epithelial cells, or RPE cells. These cells sit beneath the light-sensing cells in the retina and play a vital role in keeping them healthy.
They provide nutrients, remove waste, and help protect the retina from damage caused by light and stress. If RPE cells stop working properly, the photoreceptor cells that allow us to see can begin to die, leading to vision loss.
In their experiments, scientists exposed young and older mice to cigarette smoke, either for a short time or over several months. They then examined how the RPE cells changed. Instead of only looking for permanent DNA damage, the researchers studied something called epigenetic changes.
These are changes in how genes are turned on or off without altering the DNA code itself. Epigenetic changes can have powerful effects because they influence how cells behave, respond to stress, and survive.
The study found that cigarette smoke caused major epigenetic disruptions in the RPE cells. Important genes that normally help these cells function were switched off, while the cells also lost their ability to access parts of their genetic material needed to respond to damage.
As a result, clusters of unhealthy cells formed, similar to what is seen in people with macular degeneration.
Smoking also interfered with genes that protect against aging. These protective genes normally help maintain stable DNA, protect the ends of chromosomes, support the cell’s energy systems, and control inflammation.
When these systems fail, cells age faster and become more likely to die. Interestingly, the researchers noticed that young mice activated some protective aging genes after smoke exposure, which helped their cells survive. Older mice did not activate these defenses as effectively, and their cells were more likely to die.
To confirm that their findings were relevant to humans, the scientists also studied donated human eye tissue. They discovered hundreds of genes that changed in similar ways in both mice and humans exposed to cigarette smoke or early AMD. This suggests that the same harmful processes are happening in people who smoke.
The research shows that smoking does more than create harmful molecules that damage tissues. It also changes how cells control their genes, weakening the eye’s ability to repair itself and cope with stress. Over time, these changes may push the eye toward macular degeneration and vision loss.
Scientists hope that understanding these mechanisms will lead to new treatments that protect or restore damaged cells before vision is permanently lost. It may also help doctors identify people at high risk earlier and encourage stronger prevention efforts.
The findings provide yet another powerful reason to avoid smoking or quit as soon as possible, especially for people concerned about their long-term vision.
If you care about eye health, please read studies about how vitamin B may help fight vision loss, and MIND diet may reduce risk of vision loss disease.
For more information about eye disease, please see recent studies about how to protect your eyes from glaucoma, and results showing this eye surgery may reduce dementia risk.
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