Common Cause of Vision Loss Linked to Air Pollution — What to Know

  • According to the World Health Organization, air pollution accounts for nearly 4.2 million deathsTrusted Source per year, mostly due to stroke, heart disease, lung cancer, and chronic respiratory diseases.
  • U.K. researchers have now found that air pollution may be significantly associated with developing age-related macular degeneration (AMD), which can lead to vision loss.
  • The biggest risk factor for developing AMD is age.

Despite major gains in combatting air pollution in recent years, the World Health Organization (WHO)Trusted Source estimates around 91 percent of the world’s population lives in places where air quality levels exceed WHO limits.

According to the WHO, air pollution accounts for nearly 4.2 million deaths per year, mostly due to stroke, heart disease, lung cancer, and chronic respiratory diseases.

An observational study published Monday in the British Journal of Ophthalmology finds air pollution might also affect vision.

The findings suggest poor air quality could significantly increase the odds of developing a condition called age-related macular degeneration (AMD).

Third-leading cause of vision loss in people over 50

“Age-related macular degeneration is an age-related condition preferentially affecting the macula, which is the center of vision,” Dr. Vaidehi S. Dedania, a retinal surgeon at the NYU Langone Eye Center and assistant professor in the department of ophthalmology at NYU Grossman School of Medicine, told Healthline.

Dedania said AMD is the third-leading cause of vision loss in people over age 50 worldwide.

“In advanced stages of disease, individuals may experience loss of central vision, resulting in severe and permanent visual impairment,” she said. “AMD can be classified as ‘dry,’ also known as nonexudative, or as ‘wet,’ also known as exudative.”

Dedania said that dry AMD is more common than wet AMD, and while both forms can lead to severe vision loss, most severe vision loss associated with AMD occurs in people with the wet form of the disease.

Participants had no eye problems when study began

Researchers looked at data from 115,954 UK Biobank study participants ages 40 to 69 who had no eye problems when the study began in 2006. The participants were asked to report if they received a formal diagnosis of AMD by their doctor.

Researchers then looked at measures of air pollution that included particulate matter (PM), nitrogen dioxide (NO2), and nitrogen oxides (NOx). Vehicles emit NO2 and NOx gases.

Any structural changes in the thickness or numbers of light receptors in the retina, a sign of AMD, were assessed in 52,602 people for whom researchers had complete data in 2009 and 2012, using a type of retinal imaging called noninvasive optical coherence tomography (OCT).

At the end of the study, 1,286 participants had received AMD diagnoses, and 12 percent of those not diagnosed with the condition had signs of AMD detected by retinal imaging.

After researchers accounted for potentially influential factors, such as underlying health conditions and lifestyle, data analysis showed that exposure to higher levels of fine particulate matter (PM2.5) was associated with an 8 percent increased risk of AMD.

Exposure to all other pollutants, except coarse particulate matter, was associated with adverse changes in the eye’s retina.

More research needed

“The results of this study are fascinating, for they describe another possible risk factor for macular degeneration that can be modified to decrease one’s chances for developing this disease,” said Dr. Matthew Gorski, an ophthalmologist at Northwell Health in New York.

However, Gorski pointed out that the study was observational, so it could only show AMD is associated with air pollution.

“We have to be careful in interpreting the results of this observational study,” he said, “and understand that we cannot conclude that the pollution caused the macular degeneration.”

Gorski added that not smoking, maintaining healthy blood pressure, and eating a well-balanced diet low in saturated fats and cholesterol are the best ways to decrease the odds of developing AMD.

How is AMD treated?

Dr. Karen Saland, an ophthalmologist at Texas Health Presbyterian Hospital Dallas, said people who have drusen — fatty deposits associated with AMD that accumulate under the retina — can do things that slow the disease.

“It is essential to start taking specific vitamins that were shown to decrease the rate of progression of degeneration,” Saland said. She said these include:

  • 500 milligrams (mg) vitamin C
  • 400 IU vitamin E
  • 80 mg zinc
  • 10 mg lutein
  • 2 mg zeaxanthin
  • 2 mg copper

Saland added that people who develop wet AMD can receive injections of anti-VEGF (vascular endothelial growth factor). “Injections are at present the main treatment for wet AMD,” she said.

Age is biggest risk factor for AMD

Dr. Mark Fromer, an NYPD Honorary Police Surgeon and eye surgeon director for both the New York Rangers and the World Oyama Karate Organization, said the findings of this study should be taken “with a grain of salt.”

“I don’t know what you can do with this information,” Fromer said. “After reading the article, how do you contextually change the amount of air pollution in a given society if we already have so many laws in place to reduce such?”

He said that age is the number-one risk factor for AMD, and that longer life expectancy is a factor too.

“People who live in underdeveloped countries generally don’t live as long,” Fromer said. “So, industrialized nations might have more pollution, but then again I guess that’s not completely true, because you can have countries that have a great deal of pollution that are underdeveloped because the laws don’t keep the pollution down.”

Fromer said there are things people can do themselves to keep their eyes healthy.

They include not smoking, eating a well-balanced diet, maintaining a moderate weight, and managing high blood pressure and heart disease risk factors.

“I think that people [should] pay attention to these things that we actually can change and not wait for society to change them for us — then they’re going to have the most luck with preserving their vision,” Fromer said.

Fromer pointed out that he sees great disparity in AMD rates between the wealthier and low-income neighborhoods where he works.

Since those neighborhoods are just 10 miles apart, “I’m willing to bet [those neighborhoods] have the same levels of pollution,” he said.

One reason for these disparities may be healthcare inequities among low-income areas including a lack of access to preventive care.

The bottom line

Researchers in the United Kingdom found that air pollution may be significantly associated with developing age-related macular degeneration (AMD), which can lead to vision loss.

But experts say that although environmental and genetic factors can cause AMD, age is still the biggest risk factor for the disease. Maintaining a healthy lifestyle is the most effective prevention.

Experts emphasize that these new findings should also be taken with “a grain of salt,” since the effects of air pollution are difficult to isolate.