What is UV?
- UV or Ultraviolet Radiation can be classified as UVA, UVB or UVC according to wavelength
- UV light is not visible to the naked eye.
- UVA and UVB rays penetrate the eye whereas most UVC rays are absorbed by our ever thinning ozone layer.
When UV is absorbed by a molecule, energy is transferred to the molecule and causes damage to the tissue.
This causes changes to DNA, resulting in distorted proteins and death of cells.
Protecting your eyes from UV
- A large brimmed hat can provide up to 50% protection from UV
- Wrapped sunglasses with a UV 400 filter on the lenses provide maximum protection from UV
- Tinted lenses or sunglasses with no UV filter cause the pupils to dilate even more in sunlight than if one were to wear no lenses at all – this allows even more light flood into the eye resulting in increased UV exposure.
- Bad sunglasses = MORE damage than no sunglasses!
UV Damage in Children
- Children are more vulnerable to UV damage as they have larger pupils and clearer lenses – a greater amount of light penetrates the ocular tissues causing an increased risk of complications.
- Children spend more time outdoors – approximately 3 times more than adults.
- The lenses in children’s eyes do not block as much UV radiation as they do in adults’ eyes, putting them at increased risk for sun damage to the eyes.
- UV damage is cumulative – when damage occurs it can never be reversed, only treated.
UV Damage Effects on the Eye
A pterygium is a wing-shaped thickening of the cornea. Strong evidence suggests that it is associated with chronic UV exposure. Symptoms could include chronic irritation, induced astigmatism and decreased vision. Surgery is the only method of treatment.
A cataract is the yellowing and loss of transparency of the crystalline lens. Most cataracts are age related but can be caused by medication, trauma and disease.
According to the World Health Organisation (WHO), 20% of Cataracts are caused by UV Damage and Prevalence is higher in high risk UV areas, like sunny Southern Africa.
“Cataract is the leading cause of blindness in South Africa, responsible for about 50% of the prevalence of blindness and identified as a national health priority”
Age-Related Macular Degeneration is a disease of the central area of the retina.
ARMD causes loss of vision of the central area, only slight peripheral vision is spared.
Chronic UV exposure over a lifetime is one of the causing factors resulting in ARMD.