Effects Of Ultraviolet Light On The Eye

Various eye problems have been associated with overexposure to sunlight.

Cause Ultraviolet Ray

WHY? People are unaware of what UVR can cause to their vision/eye sight.

WHY? Insufficient spread of information to the public. Sub Problem How can we completely inform the public about the dangers caused by the UVR?

Introduction

Another radiation from the sun can harm not only your skin but also your eyes. Extended exposure to the sun’s UV rays has been linked to eye damage, which includes the cataract that clouds the eye’s natural lens that can cause to temporary vision loss.

The purpose of this project is to make the public aware of what UV ray can cause to their vision. To protect the eyes from harmful solar radiation, sunglasses should block 100 percent of UV rays. A good quality of sunglasses such as Ray-Ban is a certified item for consumption that manufactures variety of glasses and likewise lenses that deals with overexposure to sun.

This variety of lenses indicates the amount of protection it can give to the eyes. It includes the tints in the lenses that keep UV ray from reaching the eyes. Manufacturers add certain colors that block UVB light.

Amber and brown tints are especially useful at absorbing UV light; however, any light-blocking tint will help prevent eye damage. Manufacturers either use colored glass or polycarbonates to make these lenses or soak polycarbonate lenses in a tint solution. Sunglasses can also have extra UV coating, although these aren’t necessarily just for sunglasses, as the coatings are clear and can be applied to regular glasses.

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The best tint for optimizing performance is a matter of personal preference. Sunglasses labeled “UV-400” should offer good protection from the sun.

One easy way to keep your eyes protected is to remember to push your sunglasses up on your nose—the closer the lenses are to the eye, the more protection you get. If you’re going to be in a high-sun environment, wrap-around shades are a good choice.

Review Of Related Literature

Most people know of the dangers of the sun to our skin. But many do not know that too much sun can also damage the eyes. Eyes are sensitive instruments which can easily become injured or diseased from exposure to sunlight, because of the ultraviolet (UV) rays of the sun.

Ultraviolet rays are high energy, and are invisible to the human eye because they are outside the spectrum of colors that a human eye can see. Eye diseases are associated with exposure to sunlight Exposure to sunlight can cause damage to the eyes in both the short and long term. In the short term, exposure to sunlight can result in:

• Mild irritation: May cause symptoms such as excessive blinking, swelling or difficulty seeing in strong sunlight.
• Photo Keratoconjunctivitis: Photo keratoconjunctivitis is a condition similar to snow blindness or welder’s flash burn.

It occurs when the sensitive, skin-like tissues of the eyeball become sunburnt. Individuals suffering from the condition are likely to experience severe pain, and possibly temporary blindness, for 12 days. The condition is temporary and will resolve naturally. In the long term, exposure to sunlight is associated with a range of eye diseases, including:

Eye cancer (also known as squamous cell carcinoma of the eye): A rare condition characterised by the growth of cancerous cells on the surface of the eye.

The World Health Organisation (WHO) estimates that5070% of eye cancers around the world are caused by sun exposure. The risk of developing eye cancer increases with lifetime exposure to sunlight. The incidence is highest in countries closest to the equator.

Cortical and posterior subcapsular cataract: Cataracts are characterised by the increasing opaqueness of the lens of the eye. It can lead to impaired eye sight and, in severe cases, to blindness. The WHO estimate 5% of cortical cataract disease is caused by sun exposure.

In Australia, the Australian Cancer Council estimates that up to 10% of all cataracts are associated with excessive sun exposure. A study of a United States population found that individuals who had high levels of sun exposure were about 1. 5 times more likely to develop cortical or posterior subcapsular cataracts than those who had low sun exposure, while those with moderate sun exposure were about 1. 2 times more likely to develop each of these types of cataracts. * Pterygium: Pterygium is characterised by a fleshy growth on the eye’s surface.

The WHO estimates that 4070% of the global burden from this disease is attributable to sun exposure. A study conducted in Victoria reported that 43. 6% of pterygium cases were attributable to sun exposure.

Age related macular degeneration: Based on laboratory studies showing thatUV rays cause retinal damage in rats, scientists believe that exposure to UV rays contributes to the degeneration of eyesight which occurs naturally with ageing. How UVR Impacts the Eye The various tissue layers of the eye absorb the wavebands of UVR to different extents.

The longer the wavelength, the deeper the penetration of ocular tissue. Of the radiation from sunlight, UV-B has the greatest impact on the eye. Overexposure can result in photokeratitis or, in rare cases, solar maculopathy. Studies show that chronic exposure to UV-B can also cause cortical cataracts. UV-A is considered a greater threat to produce skin cancer than damage the eye. While the ozone layer filters UV-C from the sun, a welder’s arc can generate toxic dosages of this potent waveband. Since UV-C is the shortest waveband of the ultraviolet spectrum, the corneal epithelium will absorb it.

A welder’s flash burn therefore will cause a punctate epitheliopathy. Environmental factors and UV exposure The level of UV radiation varies due to a range of environmental factors,including:

* Time of day: UV radiation levels are highest when the sun is higher in the sky (in the middle of the day, between 10am and 2pm).

* Geographic location: UV radiation levels increase with increasing proximity to the equator, and increasing altitude.

* Cloud cover: UV radiation levels are higher when there is no cloud cover, although UV radiation from the sun is present even on cloudy days.

Features of the surrounding landscape: As UV radiation from the sun is reflected more or less effectively by some surfaces than others, exposure to UV radiation is also influenced by features of the surrounding landscape. Snow is a particularly reflective surface, and as much as 80% of UV radiation will be reflected back (compared to about 10% for water and grass). Dry beach sand reflects about 15% of UV radiation, while the foam in sea water reflects 25% of UV radiation.

* Ozone protection: A layer of ozone forms a protective layer around the earth and blocks much of the sun’s harmful rays, including much UV radiation.

Ozone levels vary between places and times of the day. The origin of UV protection Most of the UV protection comes from the lenses of UV protection sunglasses. Special coatings on the lenses material during manufacturing are the origin of UV protection. The exact lens coating is named UV treatment, which adds this capability to regular lenses. Always select UV protection sunglasses with labels specifying UV absorption up to 400nm, which is equivalent to 100% UV absorption. Color, style and cost have no direct help in offering sunlight protection.

Many people would think that lens color is closely related to the degree of UV protection the lenses can offer. A classical example is dark sunglasses which had dominated the sun wear industry for many years. In fact, lens darkness does not determine directly the UV filtration ability. It is the lens material and additive coating that matters. Measuring Ultraviolet Rays In the United States, the risk for UV exposure is measured using the UV Index. Developed by the NWS and EPA, the UV Index predicts each day’s ultraviolet radiation levels on a simple 1 to 11+ scale.

In addition to publishing the UV Index daily, the EPA also issues a UV Alert when the level of solar UV radiation that day is expected to be unusually high. UV  1. Wear a hat and sunglasses.

2. Cover up and use sunscreen.

3. Reduce time in the sun between 10 a. m. and 4 p. m.

| 8 – 10| Very high|

1. Wear a hat and sunglasses.

2. Cover up and use sunscreen.

3. Minimize sun exposure between 10 a. m. and 4 p. m.

| 11+| Extreme|

1. Wear a hat and sunglasses.

2. Apply sunscreen (SPF 15+) liberally every two hours.

3. Try to avoid sun exposure between 10 a. m. and 4 p. m.

How do you protect your eyes from UV radiation? Protecting the eyes from UV radiation from the sun is the only way to reduce the risk of eye damage. Staying out of the sun at all times is impossible, so it is important that you know how to protect your eyes when they are exposed to sunlight, and about the times at which the sun’s rays are most dangerous.

Steps for protecting against exposure to UV radiation from the sun include: Wear sunglasses when exposed to sunlight Every time an individual goes out in sunlight, they shouldwear sunglasses that meet the Australian standards. Sunglasses provide a barrier between UV radiation and the eyes,thus preventing the harmful effects of UV radiation. The Australian Cancer Council recommends that individuals wear sunglasses with wrap-around (i. e. side) protection complying with Australian Standard AS/ANZ 1067:2003 (these standards outline how manufacturers should make sunglasses and which materials they should use).

Sunglasses which meet the Australian Standard will be labelled with AS/ANZ 1607:2003 and a category number. In addition, the lenses of the sunglasses should offer a high level of UV protection, and be labelled UV400, or EPF9 or 10. Wear a broad-brimmed hat when exposed to sunlight A hat with a broad brim offers better protection than a cap, as it also blocks sunlight from the side and back. Such a hat can effectively block about 40% of UV rays from reaching the eye. It not only protects the eyes from exposure to sunlight, but also the ear, neck and face.

Exposureat these sitescan increase the risk of cancer. Avoid exposure to sunlight as much as possible, particularly in the middle of the day Levels of UV radiation in sunlight are highest in the middle of the day (10am to 2pm), and thus exposure to sunlight is most dangerous at this time. Limit your exposure to sunlight at this time by staying indoors, wearing protective clothing or using shaded areas. Sit or walk in the shade The shade provided by trees and canopies does not offer full protection against UV radiation, but staying out of full sunlight does offer considerable protection against UV rays.

Seek shady areas when outside, particularly when outside for extended periods or in the middle of the day. Avoid indoor sun tanning lamps Indoor tanning lamps emit UV radiation and can cause damage to the eyes and skin. Avoid indoor tanning if you wish to protect your eyes from their damaging effects. It is also important to realise that children’s eyes are susceptible to damage from UV exposure (even though this damage may not produce symptoms until they reach adulthood). In order to protect children’s eyes, parents and guardians should provide children with appropriate protective eyewear and a broad-brimmed hat, and limit their exposure to unlight, particularly in the middle of the day. When to Wear Sunglasses? Wear sunglasses outdoors, particularly in the following circumstances:

• During summer: The level of UVR at noon in summer can be more than three times as high as in winter. More importantly, the levels of UVB, the type of UVR that causes the most damage, can be as much as ten times higher (which is why sunburn takes such a short time in summer).
• Around noon: (1PM during daylight saving). Seventy percent of the harmful UVB radiation that is received each day occurs within three hours either side of this time. On the beach or boating: There are usually few buildings or structures to block the sun or sky, so people are exposed to direct and scattered radiation from the whole sky as well as reflections from water.
• Skiing at high altitude: Solar UVR increases with altitude and at 2000 metres (typical of Australian ski fields) can be as much as thirty percent higher than at sea level. The high reflectivity of snow worsens the problem, so that the UVR dose to the eye can be quite large. Consequently, good eye protection while skiing is very important.

Materials and coatings of sunglass lenses Currently, there is a wide variety of materials for sunglass lenses. Thanks to the advancements in the lens technology, different people can now choose lenses that cater individual needs. In general, sunglass lenses are made of either plastic or glass. Plastic lenses are lightweight and come in different tints. Plastic sunglass lenses can block 80% of UV rays and thus provide good protection from sunlight. While offering excellent optical quality, glass lenses are more susceptible to scratches. High index lenses

High index lenses are made of the material of high index plastic. This kind of lenses can block out 100% harmful UV rays in the sunlight. In regular, high index lenses are applied with reflective coating. This is because the high index feature also increases lens reflection on the surface. Due to the valuable optical feature of this material, high-index lenses are thinner and thinner than regular plastic lenses. Typically, lenses made of a high-index plastic can be 50% thinner than traditional plastic lenses. Patients with a severe refractive error are perfect target users.

Polycarbonate lenses Polycarbonate lenses are one of the most common types of sunglass lenses. Besides features such as lightweight and shatter-resistance, polycarbonate lenses provide natural 100% UV protection. These lenses are perfect for active adults and children. Sunglasses using polycarbonate lenses can offer incomparable eye protection and UV protection.

Photochromic Lenses

Photochromic lenses can provide appropriate lens darkness according to the surrounding environment. This type of lens always flatters people who need to frequently alternate between indoor and outdoor environments.

Without the availability of photochromic glasses, vision impaired patients need to remove sunglasses and change to prescription eyeglasses when they move indoors, or vice versa. Polarized lenses Polarized lenses are specially designed for outdoor wear. These lenses can greatly reduce glare by blocking light reflection on a flat surface. Regular participants of outdoor activities including driving, golfing and skiing can significantly benefit from polarized lenses. With the help of polarized sunglasses, the wearers will nearly be free from annoying glare.

Aspheric Lenses

Aspheric lenses are particularly suitable for people with a heavy prescription. With an evenly distributed thickness, this type of lenses will not bring an unwanted look because of excessively thick lenses. These lenses have different curves and are able to reduce or eliminate spherical aberrations. And they also help reduce the distortion of the wearer’s eyes. Scratch-resistant coating In addition to different lens materials, there are still types of coatings. In order to avoid scratches, sunglass lenses can be treated with a scratch resistant coating (SRC), which is usually included in polycarbonate and high index lenses by default.

This lens coating is especially helpful for mischievous kids who may frequently drop the glasses. Anti-reflective coating Another common coating is anti-reflective coating (ARC), which is applied in some lenses in order to reduce reflective rays. While eliminating unwanted glare during outdoor activities, lenses with this type of coating are more likely to scratch. Actually, these two types of coatings are mutually exclusive, which means one specific lens cannot have both of them. Lens tints Lens tint is another common issue. With various tint options, sunglass wearers can choose their favoritecolor in order to get distinctive looking. However, only plastic lenses can effectively and uniformly absorb tints. In contrast to high index lenses, polycarbonate lenses are harder to tint.