In summer, the temperature soars and the sun is dazzling. While enjoying the sunshine to your heart's content, have you noticed that ultraviolet rays are quietly threatening your eye health? Sunglasses are not only fashionable accessories but also crucial for protecting the eyes.
So, just how harmful are ultraviolet rays to the eyes?
How to choose a suitable pair of sunglasses?
How should different groups of people and scenarios make choices?
Everyone may be familiar with the harm of ultraviolet rays to the skin, but its harm to the eyes should not be underestimated either. The longest wavelength of ultraviolet light is 400 nanometers, which is lower than the visible light range of 400 to 700 nanometers that the human eye can see. When the eyes are exposed to light, the self-protective responses instinctively produced by the human body, such as constricting the pupils, closing the eyes and strabismus, have almost no effect in the face of ultraviolet rays. If exposed to ultraviolet rays for a long time, various tissues of the eyes, such as the cornea, lens and retina, will be damaged to varying degrees.
Cataract is one of the common "post-ultraviolet syndrome". Ultraviolet rays can denature, oxidize and polymerize the proteins in the lens, gradually making the originally clear and transparent lens cloudy. In addition, ultraviolet rays may also cause keratitis, pterygium, skin cancer of the eyes and macular degeneration. However, there is no need for everyone to worry too much. A suitable pair of sunglasses can effectively block ultraviolet rays and provide a "protective umbrella" for the eyes.
How to choose the right sunglasses?
Sunglasses are not necessarily better the more expensive they are
Sunglasses, scientifically known as "sun glasses", have been extensively studied to show that a qualified pair of sunglasses can block most ultraviolet rays. However, nowadays, the prices of sunglasses on the market vary greatly, ranging from tens of yuan to several thousand yuan. Many people may habitually think that the more expensive, the better, but the price does not entirely equal the filtering effect.
Some high-end brand sunglasses are quite expensive due to the use of high-quality materials, the application of complex and meticulous coatings and processing techniques, as well as brand added value and other factors. However, this does not mean that a high price necessarily represents perfect protective performance. Some low-priced sunglasses, although affordable, may not have undergone professional sun protection treatment for their lenses. Not only do they fail to effectively block ultraviolet rays, but they may also cause vision distortion due to poor optical performance, affecting eyesight. Therefore, when choosing sunglasses, people should not judge their filtering quality merely based on the price.
How to choose the right sunglasses
Recognize the logo
When choosing sunglasses, be sure to check the labels "UV400" or "UV100%". "UV400" and "UV100%" indicate that the lenses can block ultraviolet rays with wavelengths within 400nm. If some merchants merely label "UV protection", it is very likely to be false advertising.
The first choice is grey/brown/greenish grey
When it comes to color selection, grey, brown and greenish grey should be the top choices. They evenly absorb the spectrum without obvious color differences and can restore the true visual effect to the greatest extent.
Lens material
Glass lenses are very hard, but also heavy and fragile, so be careful when choosing them. Resin lenses are lightweight, impact-resistant and suitable for daily wear. PC lenses (polycarbonate) have excellent impact resistance and are suitable for sports occasions. Polarized lenses are suitable for driving or water activities because they can reduce glare and improve clarity.
Classification of light transmittance
Transmittance (CAT) refers to the proportion of visible light energy that passes through the lens and enters the eye. According to national standards, sunglasses are classified into four categories:
CAT1 type: The transmittance is 43% to 80%, and the lens color is relatively light. It is suitable for shopping or taking photos on cloudy days, but the shading effect is relatively poor.
CAT2 type: With a transmittance of 18% to 43%, the lens color is moderate, making it suitable for daily travel and self-driving.
CAT3 type: With a transmittance of 8% to 18%, the lens color is darker, making it suitable for outdoor sports or beach use.
CAT4 type: Transmittance 3% to 8%, the darkest lens color, and the strongest light-blocking effect. They are suitable for special scenarios such as skiing or mountain climbing. Don't wear it while driving!
How should different groups of people and scenarios make choices?
Driver: Choosing polarized lenses can filter out road reflections. However, be sure to avoid the lens being too dark in color to prevent it from affecting your eyesight at traffic lights. Grey and brown lenses are the best choices
Children: Children under the age of 6 should avoid wearing sunglasses to prevent it from affecting their vision development. Children over 6 years old can choose professional children's brands. The lenses are made of PC material, and the frames are made of soft and flexible TR90 material.
People with myopia: It is recommended to choose clip-on sunglasses first and then tinted lenses. It is not recommended to stack contact lenses and sunglasses together. If your degree of myopia is not very high, you can choose sunglasses with an appropriate degree. Coated myopia sunglasses are the top choice.
Outdoor sports: In high-altitude areas, choose high-protection and dark-colored ones. Polarizing filters for water sports; When cycling, you need a pair of well-lit sunglasses.
Warm reminder: Wear sunglasses even on cloudy days
UVA in ultraviolet rays has a strong penetrating ability. Even on cloudy days, it can still easily penetrate the clouds. So, even on a cloudy day, don't forget to wear sunglasses
