What are sunglasses?
Sunglasses are glasses worn to protect the eyes from sunlight and ultraviolet radiation (UV). If prescription lenses are tinted, polarized, or darkened, they can improve vision.
The Iranian optometrists recommend wearing sunglasses that block out ultraviolet radiation (UV) to protect the eyes from UV and blue light, resulting in several severe eye disorders. Also, they recommend wearing sunglasses that block out ultraviolet radiation (UV). Eye surgeons in Iran recommend protecting your eyes from ultraviolet radiation in any weather, which can cause various eye diseases - from conjunctivitis to cataracts and glaucoma.
Some surgical procedures, such as LASIK, require them to be worn immediately after completion. After LASEK, their use is also mandatory in dusty environments, whenever leaving the house, and when looking at a TV or computer screen.
Since dark glasses allow more UV rays into the eye and tend to enhance pupil size, it's important to note that wearing them can be as harmful as if you didn't wear eye protection since they tend to expand the pupil and increase UV exposure.
In addition to protecting you from excessive exposure to light, sunglasses also block out invisible light rays. Protection from ultraviolet radiation is the most commonly used, as ultraviolet radiation can affect the eye in both the short- and long-term and result in ocular problems like photokeratitis (snow blindness) and cataracts, pterygium, and other types of eye cancers.
Medical experts recommend that people wear sunglasses to protect their eyes from ultraviolet rays; The best way to protect yourself from UVA and UVB is to wear sunglasses that block out 99% or more of the light. This standard is often met by sunglasses marked as "UV400".
Considerations when selecting sunglasses
To begin with, you should be aware that asking for a good pair of sunglasses at an optometry store will cost your vision system more than the sunglasses themselves.
What is your purpose for wearing sunglasses? Do you want to protect against environmental factors, too much light, or to block ultraviolet rays? Furthermore, if you wear sunglasses and have a prescription for diopters in your eyes, the curvature of the frame must be taken into account; Otherwise, wearing sunglasses can cause astigmatism. Unfortunately, this critical issue is ignored in many optometry stores, and over time, it creates problems for the person.
Common features of standard sunglasses:
The Brand, The Frame, Glasses
- Sunglasses should reduce the light level to achieve adequate and proper vision.
- Sunglasses should not affect your insight and vision. That is when you wear sunglasses in a well-lit environment and move your eyes up and down or left and right, you should not feel motion and distortion in objects.
- Sunglasses frames are usually made of metal, plastic, or resin materials and should have high strength and performance.
- Reputable glasses often have well-known manufacturers and can be easily distinguished from counterfeit and non-standard samples with unique security features. Because several details of non-standard and counterfeit glasses are ignored, including the edges of the frame, the springs, hinges, and the nose bridge of the glasses, which are not designed correctly and make the user uncomfortable.
Checking the sunglasses
To check if the glasses protect well, you need to measure them at the manufacturer or special optical equipment. For example, manufacturers often label their glasses with standard UV protection ratings.
The closer the glasses fit the face, the less light they let in at the edge. (But they shouldn’t be too tight that the eyelashes do not touch the lenses.) For the same purpose, wide temples and leather lining in the form of blinders can be used.
Instruments can only assess UV protection of lenses because UV cannot be seen. Dark lenses do not always filter UV better than light lenses. It even happens the other way around. The pupils expand more from dark lenses than from light lenses, and more ultraviolet radiation enters the eyes. But dark lenses filter ordinary visible light better than light ones.
UV protection is also independent of lens color. But the color can tell if they filter blue light. For example, blue and green lenses do not filter blue light, while yellow and brown lenses filter too much, leading to color distortion and danger when driving.
You can visually check the presence of polarization: to do this, looking through the glasses taken off at a reflective non-metallic horizontal surface, rotate them along the longitudinal axis. The intensity of the glare increases with the vertical position of the glasses and decreases (up to extinction) with the horizontal position.
It is most convenient to use any LCD screen as a test surface: when you turn the glasses, the image in the glasses starts to darken (if the glasses are polarized).
Sunglasses can reduce the risk of car accidents.
If you drive on flat roads in hot weather, especially where the sun is intense, use a pair of sunglasses and stop and rest at regular breaks. When drivers are tired on flat roads, accidents are more likely to happen. Direct sunlight in drivers’ eyes causes the majority of such accidents, especially in the early sunshine and late sunset. Therefore, drivers should use protective equipment, especially proper sunglasses, to prevent possible accidents.
Climate and the sunglasses
During some seasons, such as summer, rays are felt more intensely because of heat and increased light intensity due to sunlight falling vertically on the ground. As a result, proper sunglasses should be used primarily in the summer.
In the autumn and winter, due to the sun shining obliquely, you may not mind getting more sunlight, and may not wear your sunglasses; This means that you have put your eyes at greater risk. Remember to use sunglasses even if it is cloudy outside since UV rays can cause harmful effects on the eyes and skin in any weather condition.
The next issue is radiation intensity at different times of the day. Naturally, near sunset, the UV rays are less. Most radiation occurs from about 10 am to about 4 pm in spring and summer. This starts from about 11 a.m. and reaches its maximum at about 14 o'clock in autumn and winter. At other times of the day, the intensity of the radiation decreases, but this does not mean that there are no UV rays at all.
Most sunglasses absorb UV-A of the sun's rays. However, professional mountaineers, hikers, or desert dwellers should use sunglasses that emit UV-AB wavelengths, which filter out more harmful rays. Sunglasses used in areas with higher levels of sunlight should completely cover UV-AB.
It is interesting to know that what happens on the beach that causes your skin to tan is UV-B radiation and, to some extent, UV-A, putting us at greater risk. For this reason, it is recommended not to expose yourself to direct sunlight (especially on the beach) for a long time without using protective skin coatings.
Finally, in order to choose the right sunglasses, first of all, check the standards like UV protection, ensure the sunglasses you choose can block enough light, select the sunglass that covers all your eyes and the area around them. The lens color should be checked for the purpose you desire, make sure your glasses are strong but don't put too much pressure on your nose, The price of a product should not cause you to disregard the quality and standards, choose the glasses that suit you and follow your face shape.