Glare in bright sunlight

Sunlight pouring onto the Earth

ays pouring from the sun onto the Earth include ultraviolet rays B and C, visible light, and infrared rays, and it is “visible light” that people feel glare.
However, ultraviolet rays in summer are particularly strong and become a factor that causes eye diseases. Thus, taking care for protecting the eyes from ultraviolet rays simultaneously is important.

“Visible light” that people feel glare, and invisible “ultraviolet rays”

We sometimes hear from customers that they want to cut off ultraviolet rays as a measure against glare, but to tell the truth, it is not correct.
Visible light means light of 380 to 780 nm visible to the eyes as shown in the figure.
Glare is caused by this visible light, not ultraviolet rays.
Ultraviolet rays actually cause damage, such as sunburn, age spots, and freckles, and for this reason, people tend to think that ultraviolet rays also contribute to glare.

What is the glare of “visible light”?

Of visible light, blue light, which has a short wavelength, easily scatters and causes glare.
For those acutely sensitive to glare, scattered blue light is very dangerous because it makes scenes look bright and consequently deteriorates eyesight.
In addition, glare may cause eye strain.

Measures against “ultraviolet rays” and “blue light” that should be taken together with measures against glare

In outdoor places, rays with short wavelengths, such as ultraviolet rays contained in sunlight, have strong energy, and there is a concern that they impose strain on the eyes.
For this reason, it is important to take care for protecting the eyes from ultraviolet rays and “purple light” with a particularly short wavelength of blue light at the same time.
Even some clear eyeglass lenses have the function of cutting off almost all ultraviolet rays and are effective against these rays.

Countermeasures / Improvements

• As a measure against glare in outdoor places, select lenses according to the lifestyle or the situation.
• Glare is different among individuals, and selecting an appropriate color or depth for the degree of glare is effective.
• When wearing dark-colored lenses in particular, the pupil opens, and ultraviolet rays easily enter the eyes. Thus, use in combination with these lenses a coating capable of preventing ultraviolet rays that reflect on the back surface of the lenses and enter the eyes.
  *When purchasing commercially available sunglasses, select ones with the “UV400” mark displayed on them.