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SUNLIGHT AND YOUR EYES: The sun emits rays of light-energy, and without light no vision is possible. Sunlight covers the whole visible spectrum of light, including ultraviolet light, which could be harmful to your eyes, as we will find out shortly. We will discuss the effects that sunlight may have on your eyes, and also briefly say a few things about sun protection and sunglasses.
It is extremely dangerous to look directly into the sun, because the high energy rays of sunlight are focused onto your central retina, and will cause a thermal burn wound and even a retinal hole, with permanent loss of central vision. You must educate your children regarding the dangers of sun gazing to prevent this disastrous occurrence. Some people look at solar eclipses without eye protection, resulting in permanent damage.
Sunlight has many effects on your eyes over the longer term, and we will discuss a few of these.1: Your eyelids protect your eyes from direct sunlight, and as such are very vulnerable to the damaging effects of the ultra-violet rays.
Chronic exposure to harsh sunlight may lead to loss of elasticity of the skin, resulting in crusty, dry sun-induced lesions called solar keratosis. These lesions may eventually undergo cancerous change and become little skin cancers. Adequate sun protection and minimum sun exposure can prevent this from happening. If you notice any recurrent areas of roughness or areas of skin ulceration that don't heal properly, you should consult your doctor without delay.2: Long-term exposure to sunlight may initiate certain degenerative changes in the mucous membranes of the eyes, leading to the formation of localized areas of conjunctival changes, which may present as an overgrowth of the conjunctiva encroaching upon the eye's visual axis. This condition is called a pterygium, and can be removed surgically if it reaches a certain stage of development.
3: The ultra-violet light contained in sunlight gradually damages the ocular lens over a lifetime, leading to cataract formation. A cataract is a lens that has lost its transparency, and has to be removed surgically when the patient's vision has deteriorated to such an extent that the patient has difficulty in functioning normally. Implantation of an artificial intra-ocular lens can help to regain normal vision after the cataract-extraction.
4: Due to the long-term exposure to ultra-violet light, the retina (that is the light-sensitive layer inside your eye) can also be damaged, resulting in a condition called age-related macular degeneration or ARMD. Laser-therapy can sometimes be successful in preventing the complications of age-related macular degeneration, such as hemorrhaging in the area of central vision.
5: If your eyes are extremely sensitive to sunlight, you should have your eyes examined by your ophthalmologist to exclude conditions such as allergic eye disease, viral ulcers of the cornea, glaucoma and other rarer conditions.
Prevention is the best cure,and you should invest in a good pair of sunglasses to protect your eyes from the damaging effects of sunlight and ultra-violet rays.
The advantages of sunglasses include:
1: Reduction of the glare maximizes eye-comfort, and prevents stretching of the fragile eyelid skin due to continuous squinting against the bright light, which prevents wrinkling over the long-term.
2: Polarized lenses can prevent disturbing reflections from brightly lit surfaces, which might be important in certain sports(water-sport for example) and when driving a motor vehicle.
3: Most importantly, sunglasses prevent or lessen the long-term complications mentioned earlier, by eliminating excessive amounts of ultra-violet rays reaching the ocular structures.
It is very important to choose a good pair of sunglasses to gain maximum benefit, and the following points are crucial to your decision:
1: You should stay with well-known brands if you are unsure which make to choose.
2: The lenses should have an ultra-violet filter up to wavelengths of at least 400 nanometers to cut out all harmful rays.
3: The best colour lens-tints are ones that filter out the blue side of the light-spectrum, and these lenses make everything look yellowish when you look through them.
4: If you have a refractive error such as nearsightedness for example, you should have your lens prescription incorporated in your sunglasses to gain maximum visual benefit.
5: It is important that the lenses are not too dark and that they don't cut out too much light, because then you lose visual sharpness and detail.You should just be able to see your own eyes through the lenses when looking at a mirror in good light.
Remember, badly manufactured sunglasses (especially ones without adequate ultra-violet filters) give you a false sense of security, because they don't eliminate all the harmful ultra-violet rays they're supposed to. They may even be worse than wearing no sunglasses at all, because they darken the image reaching the retina, which lets the pupils dilate and allows in more harmful ultra-violet rays than usual,and this accelerates the ultra-violet damage.
It is therefore wise to maybe spend a little more time and effort to ensure that you end up with the right pair of sunglasses.
If you have any further questions regarding sunlight and your eyes, please consult your eye specialist.