Testing of aspheric lens
The optical axis of the optical center just overlaps with the visual axis of the eye, which is the most ideal state. Because the light from the edge cannot form a focus on the optical axis, when the optical axis does not overlap with the visual axis (the difference is greater than 2mm), such unclear and scattered imaging results will occur. When choosing frames and aspheric lenses, you need to ensure that they fit correctly, to achieve the best visual and decorative effects. Simply put, due to the special design of the lens, we found through a calculation that the optical center should move down 1mm higher than the pupil for every 2° increase in front inclination angle. Otherwise, the wrong pupil height will cause the lens to look like astigmatism, and cause discomfort. For glasses with aspheric lenses, there must be an inclination angle after wearing. The specific angle varies from person to person.
When should I use blue light glasses?
Most of us spend a few hours a day in front of a screen. Because so many people work on a computer all day, many people wear blue glasses in the office. At the same time, many American high school and college students spend hours a day on their computers and could benefit from blue light glasses.
How to know if lens is polarized?
Make use of LCD screens. Point the glasses horizontally at the LCD screen and then rotate them upward by 45 degrees clockwise. If it is a polarized lens, it will show a change in color deepening. If it does not change no matter how you rotate it, it is not a polarized lens. You can borrow another person's polarized lens or have previously worn a known true polarizer, and place it crossover with the new glasses you want to buy. At this time, you should see the object clearly from the crossover part with your eyes. Then cross the glasses vertically and horizontally, and at this point, the opposite object should not be visible from the intersection. If this condition is satisfied, it means that a true polarized lens is being tested.
Blue light blocking glasses lenses and common glasses lenses have different functions.
Blue light-blocking glasses are glasses that prevent blue light from causing irritation to the eyes. Its main function is to prevent the eyes from being affected by this light and from being irradiated. It is suitable for use in extreme working environments. Blue light-blocking glasses are not for everyone. Special anti-blue light glasses can effectively isolate ultraviolet and radiation and can filter blue light. They are suitable for use when using electronic products. And common glasses are used to improve vision, eye protection, and could solve a variety of vision problems, including myopia, farsightedness, astigmatism, presbyopia or strabismus, amblyopia, and so on.
Why do glasses with the same prescription feel different?
The clarity of the lens changes. In addition to the case of the frame, the lens will be yellow or slightly scratched during use due to long-term absorption of ultraviolet rays, oily contact, dry rubbing by the user, etc., and the clarity of the lens will be affected. However, the clarity of newly equipped glasses tends to be higher, and the comparison between the two will cause discomfort. It is recommended that the new glasses can be used early the next morning. After a night's rest, the eyes will be easier to adapt to the new glasses. Under normal circumstances, new glasses generally require an adaptation period of about a week. After a few days of continuous wearing, the uncomfortable symptoms will disappear.
Choose the frame according to the hairstyle
If there are bangs, the upper edge of the frame should avoid contact with hair. If it is curly hair, it should be noted that the frame should not be too large so that the frame edge contacts the hair.
What kind of light is blue light?
Blue light is light of a certain wavelength. In the sunlight, including red light, orange light, yellow light, green light, blue light, indigo light, and purple light, blue light occupies a place. The wavelength of blue light is less than that of red light but greater than purple light. The energy intensity is also different, and the blue light is relatively less strong than red light. People must rely on the 'macula' to perceive light. The macula is a 'pearl' hidden in the fundus and the most important photosensitive part of the fundus. The macula can look at objects, generate electrical signals, and transmit the signals to the brain so that people can see the things in front of them clearly. Strong light shines directly on the eyes, and it is likely to cause damage to the macular structure at once.
