Eye Health Facts
Ever wondered why cutting onions makes you cry?
As you slice an onion, the onion cells release a gas into the air. When this gas contacts the eye, it turns into weak sulphuric acid in the moist tear layer that coats the eye. Nerve endings in the cornea react to the acid, causing the sting, and trigger the lacrimal (tear) glands to produce lots of tears in an attempt to further dilute and flush away the acid.
If onions are in water, or near running water when cut, there will be much less gas in the air, and you are less likely to start crying.
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.