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Nov 4, 2024

UV protection for the eyes: What patients need to know

By Cristina M. Schnider, OD, MSc, MBA, FAAO

Many people know that invisible UV light can cause a sunburn and contribute to skin aging and skin cancer, but there is less public awareness of the effects of UV radiation on the eyes. UV exposure has been associated with pterygium and pinguecula, skin cancer around the eyes, ocular melanoma, accelerated development of cataracts, age-related macular degeneration, and photokeratitis.1

There are 3 types of UV radiation: UV-C (100-280 nm) is absorbed by the ozone layer and generally doesn’t reach the eyes (or skin). UV-B (280-315 nm) is absorbed primarily by the cornea, and UV-A (315-400 nm) reaches the lens and, in some cases, the retina. Although a damaged lens can be replaced in cataract/lens surgery, damage to the retina and macula can’t be repaired.

Children’s eyes are especially vulnerable to UV radiation. Children tend to spend more time outside than adults do, and when outdoors, they are less likely to consistently wear sunglasses. Results from one study found that only 12.3% of children, compared with 41.6% of adults, wore sunglasses on sunny days in Hawaii.2 Children have larger pupils than adults, allowing more light to reach the retina. Finally, the younger lens transmits a high proportion of UV-A rays, gradually declining as the biochemistry of the lens develops over time. By 1 estimate, the lens of an 8-year-old person transmits 75% of UV-A radiation, the lens of a 13-year-old person transmits up to 60%, and the lens of a 25-year-old person transmits less than 5% of UV-A rays (Figure).3 Perhaps not surprisingly, approximately 30% of children aged 9 to 11 years and more than 80% of people aged 12 to 15 years already have signs of UV-related ocular changes that can be detected by UV fluorescence photography of the ocular surface.4

Protecting the eyes

UV damage is cumulative and mostly irreversible in the eye, so it is never too late to start a comprehensive ocular UV protection strategy. That should include sunscreen, a wide-brimmed hat, and sunglasses. Sunglasses should block at least 99% of UV rays (UV-A and UV-B). The most effective sunglasses are wraparound styles that fit close to the face to minimize light coming in around the edge of the frames.5

5 Increasingly, contact lens manufacturers are offering UV blocking in at least some of their contact lens brands. Class 1 UV blocking is the highest level of protection available, blocking at least 90% of UV-A and 99% of UV-B radiation (Table). Of course, although large-diameter UV-blocking contact lenses that cover the limbus protect all optical structures of the eye, the addition of a hat and sunglasses helps to fully protect eyelids, conjunctiva, and the skin around the eyes.

All intraocular lenses and spectacle lenses contain UV blockers, so it may seem surprising that UV blocking is not ubiquitous in contact lenses. A challenge for contact lens companies is that most use UV light to cure their lenses during the manufacturing process, because high-energy UV light is very efficient (think about the UV lights used in nail salons). Visible light–curing methods take more time, and reconfiguring a manufacturing line to accommodate an alternative curing method can be quite expensive. Lenses that also block some portion of the blue/violet visible light spectrum (in addition to UV) can be even more difficult to cure.

Source: Optometry Times
Read more: https://shorturl.at/6LUON
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