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The question: I've heard that your eyes can get "sunburned." How much damage does this really do to my vision?

The answer: Similar to when our skin can burn when overexposed to the sun, the structures within the eye are also sensitive to this potential damage. While we wear sunglasses for comfort and fashion, we often don't realize that we are actually protecting against potential long-term damage to our vision.

When our eyes are exposed to direct sunlight, it can lead to a burn known as photokeratitis. This exposure can leave the eyes feeling gritty and irritated. This discomfort will resolve simply by resting the eyes and avoiding further sun exposure. While photokeratitis resolves on its own, it is important to consider that just like with a sunburn – the cumulative effect of sun damage to the eyes can lead to irreversible changes that can affect your vision in the future.

The skin of our eyelids can become sun damaged, which can lead to changes that increases the risk of basal cell and squamous cell cancers and melanoma. The lower lid is at higher risk as it receives more light than the upper lid. Any new bumps or lumps on the lids, especially those with irregular borders or that bleed easily should be checked out by your doctor.

The outer clear layer of the eye, the cornea, can also become burned which can cause a blurring of vision. Sun exposure can also cause excess tissue growth on the surface of the eye known as pterygium and pinguecula that can interfere with sight if they grow to a large enough size.

The lens is the transparent disc in the eye that changes shape to help focus and filter light. Over time, with repeat exposure to sun, the lens can turn yellow and cloudy which can lead to formation of cataracts. It is estimated that 10 per cent of cataracts are due to UV exposure.

The retina is a thin, light-sensitive layer of tissue that lines the inner surface of the eye. When light hits the retina, it sends off signals to the visual centres in the brain. Some studies have shown an association between sun exposure and damage to the macula (central part of the retina) known as macular degeneration, a common cause of blindness in people over 50, but further studies need to be done to confirm this.

While the eyes have their own built-in protective mechanisms (eyelids, lens, cornea), these only offer partial coverage so sunglasses are essential. When you're choosing your glasses, pick a pair that block 98-99 per cent UVA and UVB rays. Polarized lenses can cut down on glare which reduces the intensity of sunlight reaching the eyes. Remember, sun exposure happens year round so use sunglasses for winter months too especially if you're out in the snow which can increase the light reflected to your eyes. If you work outdoors or are exposed to artificial UV radiation (dental practices, UV lights), invest in a pair of glasses that will offer you proper protection.

Dr. Sheila Wijayasinghe is the medical director at the Immigrant Womens' Health Centre, works as a staff physician at St. Michael's Hospital in their Family Practice Unit and at Hassle Free Clinic, and established and runs an on-site clinic at Women's Habitat Shelter in Etobicoke.

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