Obtaining the correct knowledge of eyeglasses and lenses, which you do not know unexpectedly, will help you to care for your own eyes and eyesight. Please use it as a reference for living a healthy and comfortable visual life.
Vol.9 Story about ultraviolet rays
Heat stroke is one of the diseases that increase in summer, and it is often mentioned in the news, but on the other hand, what is not surprisingly known is eye disease caused by ultraviolet rays.
It is also important to protect your eye health during this time of year when the amount of UV rays is high.
Therefore, this time, we will take up eye diseases caused by ultraviolet rays and introduce measures against ultraviolet rays with glasses and sunglasses.
1. What is ultraviolet light?
In the first place, ultraviolet rays (UV = UltraViolet) is not the seven colors of "visible light" of the rainbow introduced earlier, but a wavelength shorter than purple that cannot be seen by the human eye.
When it comes to UV protection in eyeglasses and sunglasses, many people think of lenses with dark colors, but UV rays are invisible light, so it has nothing to do with the presence or absence of lens color. .. Even if it is a transparent lens, if it is UV-cut, it will be a measure against UV rays.
The ultraviolet rays are classified into three types according to the length of the wavelength, and are called "UV-C", "UV-B", and "UV-A" in ascending order of wavelength. Since the properties differ depending on the type, knowing the damage caused by each can be a reference when choosing a sunscreen.
* All of it is absorbed by the UV-C atmosphere (ozone layer) and does not reach the surface of the earth.
UV-A
Due to its long wavelength, it reaches deep into the skin and destroys collagen in the dermis, causing wrinkles and sagging. In addition, some of them reach the crystalline lens and retina at the back of the eye, which is thought to be the cause of cataracts. The effect of sunscreen is indicated by PA (Protection grade of UV-A).
UV-B
Most are absorbed in the atmosphere, but some reach the surface and have a negative effect on the human body. It mainly acts on the skin and the surface of the eyes, such as damaging the DNA of skin cells, causing inflammation and blemishes.
It has also been pointed out that skin cancer is also associated with "UV-B". The effect of sunscreen is displayed by SPF (Sun Protection Factor).
2. Eye diseases caused by UV rays
Eye diseases caused by UV light include cataracts, pterygium, macular degeneration, and photokeratitis.
Of these, cataracts and macular degeneration are very well-known as eye diseases that "onset with aging as the most important cause." However, the root cause of these diseases has not been clarified, and apart from aging, "exposure to ultraviolet rays" is considered to be one of the many causes.
Cataract-Kunai-
Ultraviolet rays are absorbed by the crystalline lens of the eye, and when exposed to ultraviolet rays for a long time, the protein of the crystalline lens changes and becomes cloudy. This is a cataract. Cataracts are often thought of as an eye disease in the elderly, but the WHO (World Health Organization) reports that about 20% of cataracts are caused by UV light.
Pterygium-well-
Pterygium is a disease in which the conjunctiva (white eye area) grows abnormally and covers the cornea (black eye area). The name comes from the fact that the covering shape looks like a bird's wing. The symptoms are that the conjunctiva is covered, so the cornea is pulled and astigmatism appears, redness is likely to occur, the eyes are rough, and when the central part of the cornea is covered, the eyesight deteriorates.
Macular degeneration-Ohanhenseisho-
The macula is located in the center of the retina and is the most important part for maintaining eyesight. It is a collection of cells that identify the shape, size, color, and lightness of things. When the macula is impaired due to aging, etc., eyesight may deteriorate or things may appear distorted. In some cases, sudden loss of vision or inability to see the center of vision can lead to inconvenience in daily life.
Ray keratitis-Kousen Kumakuen-
It is also called UV keratitis or photokeratitis. It is a disease that causes scratches on the transparent film (cornea) on the surface of the black eye due to exposure to strong ultraviolet rays.
As a result, eye pain and foreign body sensation may occur, tears may appear, and the white of the eyes may become red. Depending on the degree of scratches, you may feel glare or the object may look hazy.
3. About UV cut lens
Currently, not only products made as sunglasses, but as I mentioned at the beginning of this story, most of the products are UV-cut even with transparent eyeglass lenses.
But did you know that there are two ways to cut this UV?
UV cut processing
A coating that has a UV blocking effect on the lens surface. Although it has the advantage of being inexpensive, the coating may be peeled off due to scratches or deformation due to heat, and the UV cut function may be lost even if the lens color remains.
・ UV cut material
At the stage of making a lens, a material with a UV blocking effect is mixed. Most of the lenses in prescription eyeglasses are kneaded with this UV cut material. The lens itself has a UV blocking effect, so even if it gets scratched, that effect will continue semi-permanently. Some sunglasses lenses with no degree use UV-blocking material.
Information on TV and the Internet says, "If you wear dark sunglasses, your pupils will open and your eyes will absorb a lot of UV rays." If you use sunglasses with "" in a state where the coating has fallen off due to aging etc. and the effect has disappeared, I think that such a thing can happen. Therefore, when considering sunglasses as a measure against UV rays, it is necessary to confirm whether they are "UV cut processed products" or "products using UV cut materials".
To reduce glare, a darker lens color is more effective. The darker lens color is useful in fine weather, driving in the west, and outdoors. Even a light lens color can reduce glare sufficiently during times when there is not much sunlight or for everyday use. I would like you to use different sunglasses according to your situation and environment.
4. Good points of ultraviolet rays
So far, I have explained about UV protection, but finally I will talk about the good points of UV rays.
When exposed to UV light, the skin can make a lot of vitamin D that cannot be supplemented by diet alone. And it is known that vitamin D has various actions like hormones. Vitamin D is widely known to promote calcium absorption and increase bone formation and muscle strength, but it is also said to be effective in preventing cancer, infectious diseases, and diabetes.
Vitamin D deficiency is often seen in modern people, but the cause is that many people have a lifestyle of spending the day indoors, and even when they go out, they use sunscreen externally to protect them from UV rays. And so on.
Even if you sunbathe for about 15 minutes a day, when you are exposed to the sun, "serotonin", which is said to be a happiness hormone, is also secreted, and serotonin has the effect of stabilizing your mood, leading to an increase in motivation.
You can also obtain sterilization and deodorizing effects by drying the laundry outside.
I want to think about eye health and strike a good balance between measures and utilization.
[Personal Sunglasses]
Personal sunglasses
Charmant Namiki St. Ginza, just for you to suit your lifestyle
Want to find "personal sunglasses"?
What is "personal sunglasses"?
These sunglasses allow you to freely combine frames and color lenses carefully selected by the staff.
We will find your favorite combination and hand it to you on the spot.
Of course, it is also possible to make prescription and non-prescription sunglasses by choosing the one you like from all the frames that are always on display at the store.
It may take some time to complete, so please contact the staff for details.
On the left photo:
XL1817 BU + green color lens (visible light transmittance 15%)
Bottom left photo:
XL1819 BR + gray / blue color lens (visible light transmittance 53%)