What Kind of Protection Good Sunglasses Offer?
Sunglasses are surely one of the most essential accessories of every person’s look but we shouldn’t forget their primary function – protecting the eyes! The aim of quality sunglasses is to protect our eyes from the light beams of high energy that may cause severe eye diseases later in life.
Sunglasses need to have:
Protection from UV-radiation.
Eyes without protection are harmed by UV-radiation that has become even more intense because of the weakening of the ozone layer. UV-radiation harms the eyes’ cornea and retina but quality sunglasses can eliminate the UV-radiation to the eyes completely. The smaller the amount of harmful radiation to the eyes, the less there is chance to suffer from severe eye diseases.
Protection from intensive light.
The eyes’ natural protection from excessive light is that the pupil becomes smaller and the eyes are squinting, but the light is still too bright (e.g. sunlight reflecting from snow) and the damage to retina may still occur as a result. Good sunglasses may eliminate up to 97% of the overly bright light. Photochromic or self-shading glasses are the best solution to people who wear eyeglasses as this type of glass changes its color according to the amount of sunlight: in case of UV-radiation, the glass becomes up to 70% darker, and shifting to sheer again indoors. Self-shading glasses react to temperature changes and don’t turn foggy indoors. The drawback of photochromic glasses is a slightly bigger thickness when compared to ordinary optical eyeglasses. Such glasses are also not recommended for drivers on sunny days because the car’s windshield swallows part of the UV-radiation and the photochromic glass doesn’t darken enough.
Protection form reflections.
Some surfaces like highway, water, snow, asphalt reflect a lot of light, so that it can disturb clear vision. Good sunglasses may eliminate such reflection completely using a polaroid filter. A polaroid is a multilayer plastic glass that aims to eliminate light reflecting from horisontal surfaces and to reduce eye fatigue. There is an anti-reflective layer on the inside of the glass that doesn’t let eyes be blinded by the sunbeams falling even from the side or from behind. It is even possible to study e.g. the lake bed through glasses like these. In addition, such type of glasses don’t change their darkness neither indoors or outdoors. These glasses help fishermen, dirvers and sportsmen (skiers, sailors) the best.
Making use of light frequency.
Certain light frequencies may blur vision and at the same time some other light frequencies may increase contrast. By choosing the right tone for your sunglasses, you may put it to work for your own benefit. Transitional eyeglasses are darker from the top and lighter from the bottom. This way the light radiation coming from the top is hidden from the eye but looking down is much more comfortable. One important aspect of choosing sunglasses, is the rate of the glasses’ darkness I-IV.
The rates best suited for the Estonian climate are II-III, the rate IV is meant for hikers in high mountains, sailors and skiers. Pay attention not to choose glasses for driving a car or a motor cycle that are too dark.
When wearing cheap sunglasses bought from the bazaar or supermarket, we are forced to discard nearly all of the protections mentioned above.
The biggest problem with cheap sunglasses is the way that the glasses have been manufactured. Generally, these are made of ordinary plastic and toned with a light layer of color but they are not covered with special filter coatings. Even worse is the fact that we might put our eyes under more risk when not wearing sunglasses at all. Sunglasses that lack UV-protection, diminish the intensity of visible light and as a result, the pupil increases in size letting more UV-radiation into the eye than it would without using sunglasses at all. Although the glass tone and the frame might sometimes remind us of so-called designer glasses, the quality of the glasses is completely different, but that is eventually of highest relevance for the person who wears them.
Buying quality sunglasses chosen for the appropriate circumstances, ensures us maximum benefit. For the good health of the eyes, it is important to wear sunglasses also during winter when 80% of the beams reflected back from the white snow double the UV-radiation effect on our eyes.
In order for the sunglasses to function long and well, it is recommended to carry your sunglasses in a case and not to leave them in an airless spot under the sun, e.g. visible inside the car where the glasses may deform shape because of heat.