WHY WE SHOULD ALL HAVE SUNGLASSES

[Wikimedia Commons: CC BY-SA 4.0 author by Anuragrana18]Source: BRIGHT SUN

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INTRODUCTION

Summer is coming, and is mostly the time of the year where we seems to experience the scorching heat from the sun, like in my country Nigeria, walking/working under the sun during this period can be so devastating, you can feel your blood boiling inside and some tingling effect of the sun in your brain, not to even talk of the eyes, you have to squint before you can see better. It can so bad that sleeping at night could be a nightmare, there was a time some folks had to sleep in their fridges with their birthday suit. It always a hell of a period for us, so we have to brace ourselves for it this time, but I believe this year it will be a different ball game.

According to research, many people questioned on the topic of UV radiations associated UV-related diseases with the skin than with the eye. Statistically, 95% of the people associated UV with skin problems and 85% knew about the risk of skin melanoma, but 7% were able to associate UV with eye problems. With this information, there is a need to educate the general public more widely on the dangers of overexposing the eye to UV and how best we can protect ourselves from it. This article will explain vividly UV radiations, types and a better way we can protect our eyes with good sunglasses from UV.

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WHAT IS ULTRAVIOLET (UV) RADIATION?

Firstly, let's understand UV; Ultraviolet radiation is a form of electromagnetic radiation that is all around us but it’s invisible to the human eye. UV is not light; it does not form part of the visible light spectrum but sits in between visible portion of the electromagnetic spectrum and X-rays. In a simpler way, UV rays are electromagnetic waves that the eyes cannot see.

All high energy visible (HEV) lights, as well as microwaves, Gamma-rays, Infrared-rays, X-rays, and Radio waves, are also electromagnetic waves. Their frequency and wavelength are used to differentiate them. UV radiations have wavelengths of 40-400 nanometers (nm), and since UV has a higher frequency than that of visible light, it carries more energy and has the ability to penetrate body tissues more than visible light. Prolonged exposure of tissues to ultraviolet radiations can cause serious damages, like cataract in the eye.

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SOURCE AND TYPES OF ULTRAVIOLET RADIATIONS

Naturally, UV radiations come from the sun, though it can be found in some artificial sources like tanning booths, germicidal lamps, mercury vapour lamps, halogen lights, high-intensity discharge lamps, fluorescent, welding machines, and some types of lasers.

The UV spectrum is categorized into;
• Vacuum Ultraviolet (VUV) (40-190 nm)
• Far Ultraviolet (FUV) (190-220 nm)
• UVC (220-290 nm)
• UVB (290-320 nm)
• UVA (320-400 nm).

The highest energy forms of UV (Vacuum UV, Far UV, and UVC) are completely absorbed by the ozone layer due to their low wavelength, but this also means depletion of the ozone layer (global warming) could allow high-energy UVC rays to reach the earth's surface and cause serious UV-related health problems to the eyes and skin.

However, UVB and UVA have lower energy and slightly longer wavelengths than the others; their rays are partially filtered by the ozone layer, which allow some to reach the earth surfaces in small doses. UVB have the ability (energy) to penetrate tissues, but due to its low wavelength it’s not completely absorbed by the ozone layers, this makes it the most destructive of all the UV radiation. UVB radiation is responsible for the production of melanin (the pigment responsible for dark skin), continuous exposure leads to SUNTAN.

UVA have lower energy level than the UVB, this makes it’s least harmful from the other ultraviolet lights, but it’s penetrate the tissues more than the other UV lights. Like in the eye, its can pass through the cornea and reach the lens and retina inside the eye. Very little of the UVA radiations are absorbed in the atmosphere by the ozone layer, so there are present in much quantity in the earth's surface, even on cloudy days.

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OCULAR DISEASES CAUSE BY UV RADIATION

UV exposure has been implicated as a risk factor of a large number of eye diseases, their effects on the biological tissues is determined by their varying wavelengths, and also the different ability of these tissues to absorb them. The cornea and the lens are the tissues of the eye that mostly absorb UV. UVB are mostly absorbed by the cornea, while the lens absorbs most of the UVA, though it can be absorbed by the retina.

Continuous exposure of the eye to the sun's ultraviolet rays can cause or heighten eye diseases like:

• MACULA DEGENERATION
  It’s a progressive damage of the retina overtime. The retina is the part of the eye responsible for sharp images. Prolonged exposure of the retina to UVA radiation increases the risk of developing macula degeneration. The macula is the part of the retina responsible for the central, high-resolution, color vision.

• CATARACTS
  This is the clouding of the lens; the part of the eye that helps in focusing the light we see. 100% of UVB are absorbed by the lens, and this increases the risk of developing cataract overtime.

• PINGUECULAE AND PTERYGIA
  Both are non-cancerous growths found on the conjunctiva and cornea due to long term exposure to UV radiations. The difference between them is that pterygium is pinkish in colour, while pingueculae looks like a bum or yellow spot.

• PHOTOKERATITIS
  This is likening to a sunburn or suntan of the cornea or conjunctivitis. It’s caused by overexposing the eye to UVB radiations. It’s a painful eye condition, symptoms includes tearing and feeling of sand in the eye. Long hours at the beach or skiing without proper eye protection can lead to this problem.

HOW TO PROTECT OUR EYES FROM UV RADIATIONS.

This risk or damage to our eyes by UV radiation continues to grow as we spend more time in the sun without proper protection. To best protect your eyes from UV rays, always wear good quality sunglasses when you are outdoors. Most costly sunglasses might not give you 100% protection, look for sunglasses that block 100 percent of UV rays, an optician can help you choose the best sunglass lenses for your needs.
The amount of UV protection sunglasses offers does not depend on the colour and darkness of the lenses. For example, a light amber-colored sunglass can provide the same UV protection as a dark gray sunglass.
To protect as much of the delicate skin around your eyes as possible, you can go for a close-fitting wraparound style sunglass. If you are dark-skinned and eyes, you still need to wear sunglasses. Although your dark-skinned may give you a lower risk of skin cancer, but you face the same risk of eye damage as that of someone with a fair skin.
Even when you are in a shade always wear your sunglasses, though the shade might block out most of the rays, but some surfaces might reflect it to your eyes, also note that even in cloudy sky, some UVA can still radiated, this is because UV rays are invisible radiation, not visible light, and can penetrate clouds.
Children are more at risk than adults, because children generally spend much more time outdoors than adults, also children are more at risk to retinal damage from UVA because their lens are more clearer than adult’s, allowing more UVA rays to penetrate deep into the eye. Therefore, ensure your children wear good quality sunglasses or photochromic lenses when they are outdoors. Also, encourage them to wear a hat on sunny days to further reduce exposure to UV rays.

CONCLUSION

Since damages to our eye cells are irreversible, measures like wearing sunglasses under intense sunlight can be helpful in reducing the influx of temporary vision loss. The same way we protect our skin with clothes and expensive body lotion from ultraviolet (UV) radiation from the sun which can lead to skin cancer, we should also be aware of the connection between UV radiation and eye diseases.

With increased levels of UV radiation reaching the Earth’s surface due to some environmental conditions, it is very important to take the necessary precautions to protect your eyes. Importance should be placed on starting ocular UV protection from a young age, perhaps better information, should be to advise individuals on the use of combined protection: a wide brimmed hat or face cap; good quality wrap around well-fitting sunglasses.

REFERENCES

• What is Ultraviolet Light?-Definition, Wavelength & Uses

• WHAT IS ULTRAVIOLET LIGHT

• HOW DOES UV LIGHT AFFECT EYESIGHT

• ULTRAVIOLET (UV) RADIATION AND YOUR EYES

• UV RADIATION AND THE EYE-KAREN WALSH

• PHOTOKERATITIS

• PTERYGIUM

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