UV light is harmful to your eyes, both in the short term and over a lifetime of exposure. It can burn the surface of your eye in a matter of hours, and years of cumulative exposure raises your risk of cataracts, macular degeneration, and even eyelid cancers. The damage depends on the type of UV radiation, how long you’re exposed, and how well your eyes are protected.
How UV Light Damages the Eye
Your eyes are vulnerable to all three types of ultraviolet radiation: UVA, UVB, and UVC. Each penetrates to different depths. UVB is largely absorbed by the cornea and lens, the front structures of the eye, while UVA passes deeper and can reach the retina at the back. UVC, the shortest and most energetic wavelength, is normally blocked by the Earth’s atmosphere but can come from artificial sources like germicidal lamps.
The core problem is that UV radiation generates reactive oxygen species, unstable molecules that damage cells from the inside out. In the cornea, this triggers inflammation and can strip away the outermost layer of cells. In the lens, UV radiation kills the cells that keep the lens clear and flexible, gradually turning it yellow and opaque. The retina is especially vulnerable to oxidative stress because of its high oxygen levels and constant exposure to light. Over time, this damage accumulates in ways your body can’t fully repair.
Short-Term Damage: Photokeratitis
Photokeratitis is essentially a sunburn on the surface of your eye. It happens after intense, short-duration UV exposure, the kind you get from a day on snow without sunglasses, staring at a welding arc, or spending hours on highly reflective water. Symptoms include eye pain, redness, watery eyes, blurry vision, light sensitivity, and a gritty feeling like sand is stuck under your eyelids. Less commonly, people report seeing halos, headaches, eyelid twitching, or temporary changes in color vision.
Symptoms typically show up within a few hours of exposure and last anywhere from 6 to 48 hours. The condition almost always resolves on its own without lasting damage. But the experience is painful enough to sideline you for a day or two, and repeated episodes add to the cumulative UV load on your eyes.
Long-Term Risks: Cataracts and Macular Degeneration
The more serious consequences of UV exposure develop over years or decades. Both UVA and UVB radiation contribute to cataract formation, a clouding of the lens that progressively blurs your vision. The mechanism is straightforward: UV light triggers chemical changes in the proteins that make up the lens, causing them to clump together and lose transparency. Cataracts are the leading cause of blindness worldwide, and while aging is the primary driver, UV exposure is a well-established accelerating factor.
Macular degeneration, which destroys the central part of your vision, also has a UV connection. The retinal pigment layer at the back of the eye accumulates damage from UV-generated oxidative stress over a lifetime. Short blue-violet visible light in the 400 to 440 nanometer range, just beyond the UV spectrum, adds to this retinal stress. For people over 50, filtering out these wavelengths with properly designed sunglasses or contact lenses can help reduce risk.
Eyelid and Surface Cancers
The skin of your eyelids and the thin membrane covering the white of your eye (the conjunctiva) sit directly in the path of UV radiation. Basal cell carcinoma is now the most common eyelid skin cancer worldwide, and UV exposure is a key risk factor. Chronic UV exposure causes roughly 90% of squamous cell carcinomas in these tissues. Eyelid melanoma is linked to both intermittent intense sun exposure and long-term cumulative exposure, with risk varying by skin tone and geographic region. All of these cancers carry the characteristic DNA mutation signature of UV damage.
Why Children’s Eyes Are More Vulnerable
Children face higher risk from UV exposure than adults for a simple anatomical reason: their lenses are clearer. An adult’s lens has yellowed enough over the years to act as a partial UV filter, absorbing some radiation before it reaches the retina. A child’s lens transmits significantly more UV light through to the back of the eye, and their pupils tend to be wider, letting in more light overall. This means UV radiation reaches the retina of a child’s eye in quantities that an adult’s eye would naturally block. The damage contributes to a buildup of cellular waste products in the retina that may play a role in macular degeneration decades later.
Peak Exposure Is Not When You Think
Most people assume their eyes get the most UV exposure during midday, between 10 a.m. and 2 p.m., when the sun is strongest for skin burns. But research from Kanazawa Medical University found that UV exposure to the eyes during early morning and late afternoon was roughly double the midday exposure during spring, summer, and fall. The reason is the sun’s angle. When the sun is lower on the horizon, its rays hit your eyes more directly instead of coming from overhead, where your brow ridge and eyelids provide some natural shading. This means you need eye protection for more of the day than you might expect.
Reflective Surfaces Multiply Exposure
The environment around you dramatically affects how much UV reaches your eyes. Snow reflects up to 80% of UV rays back toward your face, which is why snow blindness (a form of photokeratitis) is so common among skiers and mountaineers. Sand reflects about 15%, and grass, soil, and water each reflect around 10%. Being near snow essentially doubles your UV dose compared to standing on grass, because you’re getting hit from above and below simultaneously.
Artificial UV Sources
Germicidal lamps, which use UVC radiation to disinfect surfaces and air, pose a concentrated risk. Research has shown that as little as 30 seconds of direct exposure to some germicidal lamps can cause irreversible changes in retinal cells. Accidental exposure can produce photokeratitis, corneal inflammation, and retinal damage. Retinal cells are particularly sensitive to UVC, with cell death rates reaching up to 70% at higher doses in laboratory studies. If you work around germicidal equipment or have a UV sanitizing device at home, never look directly at the light source, even briefly.
Choosing the Right Sunglasses
Look for sunglasses labeled UV400, which block wavelengths up to 400 nanometers and provide nearly 100% protection against both UVA and UVB radiation. This is the single most important specification on any pair of sunglasses. Lens darkness and color have no bearing on UV protection; a dark lens without UV coating actually makes things worse by dilating your pupils and letting in more unfiltered radiation.
Polarization and UV protection are two separate features. Polarized lenses reduce glare from reflective surfaces like water and roads, which improves comfort and visibility. But polarized lenses do not inherently block UV light. You need to confirm that any polarized pair also carries a UV400 or “100% UV protection” label. Wraparound frames offer added benefit by blocking UV that enters from the sides.
For children, sunglasses with full UV protection are especially important given how much more UV their eyes transmit to the retina. Wide-brimmed hats help, but they only reduce UV to the eyes by roughly half, so they work best as a complement to sunglasses rather than a substitute.