Outdoor Artificial Lighting Linked to Increased Risk of Vision Loss: Study

But expert urges caution in interpreting findings due to limitations in estimating light exposure.

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The glare of streetlights, neon signs, and other outdoor lighting fixtures may do more than just disrupt sleep cycles. It may also increase the risk of vision loss, according to a new study.

Researchers in South Korea have found exposure to artificial light at night can raise the chances of developing age-related macular degeneration (AMD), characterized by damage to the retina. The progressive disease impairs central vision, making everyday activities like reading and driving difficult.

AMD Can Lead to Blindness

AMD is a progressive eye disease that damages the macula, a small area in the retina’s center. While it can potentially cause irreversible blindness, it results in severely reduced central vision for most people. AMD has both genetic and nongenetic risk factors.

There are two types of AMD:

• Wet AMD, also called exudative AMD, is caused by leaking blood vessels in the macula. It is treated with light therapy and medication and is most common after age 55.
• Dry AMD leads to blurred central vision due to the inner layers of the macula slowly breaking down. There are currently no treatments to reverse the damage from dry AMD.

Advancing age is the greatest risk factor for AMD. Smoking and low antioxidant intake also increase risk. Among environmental factors, light exposure can damage the retina and optic nerve.

The retina is composed of “very sensitive tissue,” Dr. Khurram Chaudhary, a vitreoretinal surgeon and director of Retina Service at Stony Brook Medicine, told The Epoch Times. “It’s the inner lining of the eye,” he said. “So any sort of damage externally or internally can cause degeneration of those cells.”

External factors include light and trauma to the eye, while internal factors include smoking cigarettes, unhealthy eating, and cardiovascular disease, Dr. Chaudhary added.

Besides light exposure, there are four major AMD risk factors:

• Genetics or a family history of AMD.
• Caucasian ancestry.
• Light-colored eyes and hair.
• Smoking.

Outdoor Lighting May Double AMD Risk

Previous research has linked blue-light exposure from sunlight with chronic retinal damage and AMD. Now, a South Korean study published in JAMA Network Open suggests outdoor artificial light at night is another risk factor for the progressive disease.

Using national insurance data, researchers identified 4,078 people diagnosed with wet AMD from 2010 to 2011 and matched each by age and sex with 30 controls with no AMD record through 2020. Outdoor light exposure was estimated using 2008–2009 satellite data.

People in regions with the most street lighting and artificial light had over twice the AMD risk compared to the least-lit areas, even after accounting for sleep problems and depression. Living in an area with slightly more nighttime lights than the least-lit regions was linked to a 12 percent higher AMD risk.

“These findings align with the increasing body of evidence that emphasizes the negative impact of OALAN (outdoor artificial light at night) on health, further implicating OALAN as a potential risk factor for [exudative] AMD,” the authors wrote. “Further studies incorporating comprehensive information on exposure, individual adaptive behaviors, and potential mediators are recommended to deepen our understanding in this area.”

Measuring Light Exposure and AMD Risk Very Difficult: Expert

While people are exposed to more outdoor artificial light, they also face significant artificial light exposure at home from devices like TVs, smartphones, and computers, Dr. Chaudhary said. This makes the exposure data in the study hard to calculate, as differences in indoor artificial light exposure weren’t factored between participants.

“So before we say [outdoor street] light absolutely can cause this, you have to go dig deeper and to see actually how much light someone gets,” he added. “And I feel like that’s very, very difficult.”

According to Dr. Chaudhary, the study found an association that should be further examined by looking at light type, wavelength, and exposure time to understand if lighting worsens macular degeneration.

Light exposure is something that should be discussed with patients, including wearing sunglasses in daylight, which may help slow progression and does no harm, he noted. “But I’m not going to go out of my way and, say, wear sunglasses at night, too, because that’s dangerous in itself,” Dr. Chaudhary said.

Healthy Diet, No Smoking Key to Preventing AMD

Based on the study, wearing adequate sunglasses during sunny days is essential, Dr. Chaudhary said. But even more critical is having a healthy diet and not smoking, he added.

These two factors are “absolutely imperative” and just as—if not more—important than the study findings. However, the findings won’t change his practice yet, but he will mention them to patients “just so they can kind of keep it in the back of their mind,” he said.

Specific nutrients like antioxidant vitamins A, C, and E and the minerals zinc and selenium help reduce the risk of AMD. However, only vitamin A plays an essential role in retinal cells, while vitamins C and E act just as protective antioxidants.