By Ebiye Beedie, BSc (Hons) Optometry, MCOptom
With the dry season not too far away, I thought it appropriate that this edition of Eye Matters be dedicated to discussing the effect the sun has on our eyes. It is loved for tanning the skin, encouraging crop growth and lifting our moods, but the truth is the sun is not always on our side. Although we may all be aware of the dangers to our skin and the importance of sunscreen, do we know how to protect our eyes?
UV Radiation
If you cast your mind back to those science lessons in secondary school, you may recall learning about the Electromagnetic Spectrum. All we need to know, for the purposes of this article, is that within this spectrum are various types of radiation, each with different wavelengths (see Figure 1). One type of radiation emitted by the sun is Ultraviolet radiation, commonly referred to as UV. UV radiation has very short wavelengths and can be split into three types – UVA, UVB and UVC, with UVA having the longest wavelength and UVC the shortest. While UVC is usually absorbed by the ozone layer, UVA and UVB are free to reach us here on earth.
The effect on us
UVA can be absorbed by the lens in the eye. As we have seen in previous editions of Eye Matters, the lens is responsible for ensuring light is focused on the eye. To do this effectively, it is essential that it is transparent. When UVA is absorbed by the lens over time, it reduces this transparency and can lead to cataracts or exacerbate existing ones. This can cause blurred vision and eventually affect everyday activities. UVB has a shorter wavelength than UVA, which means it is absorbed by structures closer to the front of the eye. At risk of damage by UVB radiation is a structure called the cornea, which, like the lens is essential for focusing light. Long-term exposure to sunlight can cause damage to the cornea that can negatively affect vision. However, very high exposure to UVB over a short period time (when skiing, for example) can cause a severe response and lead to a condition referred to as ‘snow blindness’. Fortunately, this condition tends to be reversible and symptoms are short-lived.
There are several options, all of which aim to reduce exposure.
1. Wear a hat: Not only are hats a great accessory, but they also cover your eyes by casting a shadow over them, protecting them from the sun and its potentially harmful UV rays.
2. Sunglasses: Sunglasses have a legal requirement to block UVA and UVB light, which means they prevent UV radiation from entering our eyes and being absorbed by the structures.
3. Contact lenses: Now for those who wear contact lenses, you should be aware that some actually have UV protection, providing additional protection for your eyes. This is best when used with sunglasses and not as an alternative to them. This article has summarised UV radiation, the effect on our eyes and ways to reduce UV exposure. So let us enjoy the sunny Harmattan season, knowing that our eyes are protected… because your eyes matter.

SI Magazine

Leave a Reply

Your email address will not be published. Required fields are marked *