What is a photochromic lens?
Photochromic lenses are lenses that become dark when exposed to a particular wavelength of light (usually ultraviolet light), but return to their original transmittance and become clear when no longer illuminated by the light source. Photochromic lenses can be made of glass or resin. The discoloration effect is caused by silver chloride or other halides added to the lens, which are transparent to visible light when not irradiated by ultraviolet light. When irradiated by ultraviolet light, chemical reactions will occur, which will absorb part of the visible light and make the lens show dark. The chemical reaction is reversible, so the lens returns to its original transparent state when it is no longer exposed to UV light.
Retro glasses
The retro glasses have a strong retro flavor. Then, of course, you should choose a special design to wear, simple will make you stand out from the crowd. The square full frame is very retro, using special metal. The metal frame wears comfortable and has a better decorative effect.
Difference Between Driving Glasses And Night Vision Goggles
The special effect of polarized glasses is to eliminate and filter the scattered light in the beam of light effectively so that the light can be put into the visual image of glasses with the right track, and the field of vision is clear and natural. The effect of night vision goggles is that they allow the wearer to observe the surroundings at night without being affected by light. For example, aviation accidents can be greatly reduced through the use of navigation winches equipped with forward-looking infrared cameras on aircraft and by requiring pilots to wear goggles fitted with night vision goggles.
Metal frames have many benefits.
It has a certain hardness, good softness, good elasticity, wear resistance, corrosion resistance, gloss, and good color and luster.?For example, for the high nickel alloy frame, nickel content reaches more than 80%. It mainly has nickel-chromium alloy, manganese nickel alloy. High nickel alloy’s corrosion resistance is better. In addition, the material elasticity is good.?Titanium frame has a high melting point, light material, strong corrosion resistance, and solid electroplating. The eyeglass frame that uses pure titanium is deft and comfortable, more in accord with human body engineering. And flexibility is good, long-term use is not out of shape. And they do not fade, do not cause skin allergy, relatively durable.? Memory titanium alloy frame refers to a new alloy made up of nickel and titanium according to the atomic ratio of 1:1.?Memory titanium is more resistant to corrosion than high nickel alloys but less resistant than pure titanium and β-titanium.
What is the cheapest way to buy prescription glasses?
Optometry must be accurate. Optometry is the main basis for glasses. The accuracy of optometry is directly related to the success rate of the glasses prepared. Optometry must be accurate first, and the difference between the upper and lower levels should not exceed 12.5 degrees of the prescription. Secondly, the astigmatism axis should be accurate, and the general axis difference should be limited to plus or minus l to 3 degrees. In addition, the interpupillary distance must be accurate, and the interpupillary distance must be equal to the optical center distance of the lens. If you do not pay attention to the above-mentioned checkpoints in optometry, the prepared spectacle lenses will have blurred vision, prolonged visual fatigue, dizziness, nausea, and even diplopia. Optometry is best to go to a professional eye hospital. For children’s optometry or to wear glasses for the first time, you must use mydriatic optometry to be accurate. You can also check if there is any problem with the fundus, and go to the hospital to get more accurate optometry.
Don’t Do When Cleaning Glasses
Here are something you can’t do when cleaning the glasses.
1. Don’t use your shirttail, blouse, or other clothing to clean your glasses, especially when the lenses are dry because they will scratch your lenses.
2. Don’t use the saliva to wet your lenses.
3. Don’t use some surface cleaners to clean your eyeglasses because they may damage glasses lenses and coatings.
4. Don’t use some paper to clean your lenses, such as paper towels, napkins, or some tissues. They may scratch or smear your lenses or make them full of lint.
5. Don’t try to remove a scratch on your lenses by buffing away. This action can make the situation worse.
How Do Progressive Lenses Work?
So, how do progressive glasses work? Progressive lenses allow you to see at all distances with one pair of glasses. They start with your distance prescriptions at the top of the lens and increase as you move toward the bottom of the lens. You can move your head position to allow you to focus through different areas of the lens.
Move your head upwards to see something in the distance, and hold it straight for intermediate or arm’s length vision and down for near vision for objects that are close up. Apart from the aesthetic improvement of the lens without the line segments, progressive lenses avoid the visual discontinuity or image-jump when your eyes shift from one zone to the other in non-progressive multifocals.
