Eye Health Facts
Aura, after-images and things like that.
Most of the time our vision works automatically, adjusting to changing light levels, colours and shapes and movement, without us noticing the complex task it is performing. But in certain situations so often we get a glimpse at the workings of our visual system:
- Bleaching takes place when you look at something bright - it takes a little while for the 'afterimage' to fade and vision return to normal.
- Look at an object of a bright colour for a while, and then at a white page, and you'll see an 'afterimage' in its complementary colour.
- Stare at an object of a bright colour against a blank background for a while, and because of the small movements the eye makes, this complementary colour afterimage will appear as an 'aura' at the edges of the object.
Eye Health Facts
UV and the eyes
Ultraviolet is invisible light just off the blue-violet end of the colour spectrum. Being short wavelengh, it is high energy, and as anyone with a sunburn will tell you, get enough of it and it damages tissue. High dose UV can cause eye lid sunburn, 'arc eye' and 'snowblindness' as it burns the cornea. But what about long-term exposure?
Long term UV exposure has been linked to cataracts, pterygia and macular degeneration. Cataracts are a clouding of the lens inside the eye leading to poorer vision and glare sensitivity. A pterygium is a connective tissue growth on the front of the eye, which can get inflamed and interfere with vision. Macular degeneration is a change in the retina at the back of the eye, reducing vision and is the most common cause of legal blindness.
Reduce your UV exposure with UV blocking lenses and a broad brimmed hat when out in the sun, and in time to come your eyes may thank you for it.