Correlation: Cataracts and UV exposure in driver-side windows

July 20, 2016
Sun exposure linked to ocular issues.

Excerpted from page 50 of the July/August issue of AOA Focus

In North America, cataracts and skin cancers appear on the left side of the face at a greater frequency than on the right. Because the opposite correlation occurs in countries that drive on the other side of the road, experts have long suspected that sun exposure through the driver-side window contributes to the accumulated ultraviolet (UV) radiation exposure that exacerbates the formation of cataracts and certain skin cancers.

A recent study, published in the journal JAMA Ophthalmologyy, assessed the levels of UV-A light that seeped through the front windshield and driver-side window of several automobiles.

The lead researcher in the experiment was Brian Boxer Wachler, M.D., of Beverly Hills, California. Using a handheld UV-A light meter on a cloudless Southern California afternoon, he measured the amount of radiation behind the front windshield and the driver-side window of 29 automobiles, spanning 15 different manufacturers and ranging from almost new to 26 years old. The protection afforded by windshields was consistent and formidable, blocking an average of 96% of UV-A radiation. Driver-side windows blocked much less UV-A light and varied widely from model to model. Only four driver-side windows of the 29 cars tested blocked more than 90% of the radiation. Luxury was no guarantee of support either. A 1990 Buick Riviera offered more protection than a late-model Lexus, Audi and Tesla.

Over exposed

"I definitely think that sun exposure is one of the greater contributing factors to cataracts," says Saysha Blazier, O.D., a member of AOA's Health Promotions Committee who practices in Jersey City, New Jersey. "Part of it is in your genes. In some families, every person develops cataracts more easily, and getting sun exposure can progress that more rapidly."

Dr. Blazier recommends that her patients invest in a pair of sunglasses that offer full-spectrum UV protection. People who are darker pigmented are not as photosensitive to glare as those with fair skin and light eyes, she says, but they should still reach for their shades when facing the sun. Children, too, can accumulate damage at an early age. "Typically cataracts in children are more of a congenital nature and not developed by environment factors," she says.

Beyond the eyeballs

"There are other ocular findings that go along with UV damage," says Brad Lane, O.D., a member of AOA's Health Promotions Committee who practices in Princeton, West Virginia. "When you see a patient come in with pterygium, pinguecula and cataracts, you know this person spends a lot of time in the sun."

"Dr. Lane, whose own car sports a driver-side tint with UV-protecting properties, feels strongly that doctors of optometry should examine the entire area that surrounds the eye–especially when it comes to UV damage–and not limit their exam to the structure of the eyeball.

"I was trained to look at noses and ears for sun damage. I don't want to overstep my bounds and diagnose someone with melanoma, but if I see something suspicious, I am going to mention it," says Dr. Lane, who has detected cancerous lesions on three different patients over the course of his career.

Both Dr. Lane and Dr. Blazier are quick to point out that whatever the damage is, whether it be to the skin or the eyeball, most of it can be caught and mitigated with an annual check-up.

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