Health effects of UV radiation
The eye is recessed within its orbit and shielded by the brow ridge, the eyebrows and the eyelashes. Bright light activates the constriction of the pupil and the squinting reflex to minimize the penetration of the sun’s rays into the eye. However, the effectiveness of these natural defences in protecting against the dangers of UV radiation is limited under extreme conditions such as sunbed use or strong ground reflection from sand, water and snow. Acute effects of UV radiation exposure include photokeratitis and photoconjunctivitis. These inflammatory reactions are comparable to a sunburn of the very sensitive skin-like tissues of the eyeball and eyelids, and usually appear within a few hours of exposure. Both can be very painful, but are reversible and do not result in any long-term damage to the eye or vision. Extreme forms of photokeratitis are 'arc-eye' and 'snow blindness'.
Cataracts are the leading cause of blindness in the world. Proteins in the eye’s lens unravel, tangle and accumulate pigments that cloud the lens and eventually lead to blindness. Even though cataracts appear to different degrees in most individuals as they age, sun exposure, in particular exposure to UVB, appears to be a major risk factor for cataract development.