Sunburn is caused by exposure to the ultraviolet (UV) rays of the sun. There are two types of ultraviolet rays, UVA and UVB. UVA rays penetrate the skin more deeply and can cause melanoma in susceptible people. UVB rays, which don't penetrate as deeply, cause sunburn and wrinkling. Most UVB rays are absorbed by sunscreens, but only about half the UVA rays are absorbed.

The ultraviolet rays in sunlight destroy cells in the outer layer of the skin, damaging tiny blood vessels underneath. When the skin is burned, the blood vessels dilate and leak fluid. Cells stop making protein. Their DNA is damaged by the ultraviolet rays. Repeated DNA damage can lead to cancer.

Fair-skinned people are most susceptible to sunburn, because their skin produces only small amounts of the protective pigment called melanin. While they have a lower risk, even the darkest-skinned people can get skin cancer.

Skin cancer from sun overexposure is a serious health problem in the United States, affecting almost a million Americans each year. One out of 87 will develop malignant melanoma, the most serious type of skin cancer, and 7,300 of them will die each year.

Glare is the sensation produced by the reflection of, or over-abundance of light within the field of vision. Glare can cause discomfort or a reduction in visual performance.

When the eye is exposed to sunlight, the natural response is for the pupil to contract its opening and the eyelids squint, thus decreasing the amount of light that enters the eye. If glare is present, the eye strains to see objects through the glare. All of this involves a physical reaction of the eye and its surrounding muscles. Over a period of time, eye fatigue induced by this response, also becomes a problem, further diminishing your visual capabilities, if not leading to severe headache and eye soreness.