Sun protection for the eyes- what’s the fuss?
While the sun is 150 million kilometres away from earth it takes a mere 8 minutes for its light waves to reach us with the sun producing infrared, visible and ultraviolet light as well as X-ray radiation during solar flares.
While infrared light (heat) may be harmful in high doses such as in arc welding, we don’t have to protect ourselves from normal every day exposure.
Visible light allows us to see colour and X-ray radiation from the sun is rare.
So that leaves us with ultraviolet radiation which is absorbed to some degree by the ozone layer. Ozone absorbs more than 99% of UV-C rays , about 90% of UV-B and only about 50% of UV-A.
When it comes to the eyes it is important to wear glasses and sunwear that carries the UV400 rating; this means that all ultraviolet radiation up to 400nm in length is blocked.
UV damage to the eyes;
Photo keratitis- this is likened to a sunburn of the eye and usually occurs with intense UV exposure such as after a day out on the water or skiing without adequate protection. This leads to surface damage on the cornea and conjunctiva and causes a gritty, foreign body sensation with light sensitivity.
Pingueculae and pterygia- fatty or fibrous vascularised growths which develop on the eye surface with chronic sun exposure- typical in surfers and sailors or anyone who has spent a lot of time in the outdoors. These lesions become dry and inflamed with pterygia leading to visual disturbance and even sight loss if not removed surgically.
There is an important correlation between those with pterygium and having a higher risk of skin melanoma; so please get your skin checked regularly if you have one!
Cataracts- the lens inside our eye is crystal clear at birth but becomes opaque with chronic exposure to environmental toxins and ultraviolet light.
Macular degeneration- the central retina which is responsible for our fine visual tasks is susceptible to photo-chemical damage from chronic exposure to light and oxygen. There is a particular relationship between exposure to the shorter wavelengths of the light spectrum (blue light) and oxidative stress which may lead to macular degeneration.