Main > Health > Optics/glasses/spectacles
Cleaning your glasses: NEVER clean your lenses when they are dry. If the lenses are dry then you will grind dust into the lenses, causing them to scratch. It is best to first rinse the glasses off before cleaning them. Always use water, or special glasses cleaner. Don't use alcohol or acetone. Use only a soft microfiber cloth to carefully wipe the lenses.
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Main > Health > Optics/glasses/spectacles
Don't buy your glasses at a "boutique" store, or you will pay many times more than what you need to. Get your prescription only, and make sure the optometrist records your "pupillary distance" (PD) on your prescription. Then you can find a cheap place online, and order your glasses online. Make sure that the frames you buy are the correct width for your face, and that the lens height is high enough for the kind of lenses that you need. Progressive lenses require more lens height. If ordering reading, or computer glasses online then you will need to provide the "Add" number on your prescription (or add the "Add" number to the "sphere" number, for each eye, if there is no provision to provide it).
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Main > Health > Optics/glasses/spectacles
Polycarbonate lenses can produce slightly less sharp images than plastic or glass lenses, but are thinner, lighter, stronger, and more scratch resistant. They are also UV resistant. Glass is the best optical material, but is significantly heavier, and shatters more easily. Plastic (CR-39) is the most popular material for glasses lenses, and is a compromise between the two.
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Main > Health > Optics/glasses/spectacles > Sunglasses
Sunglasses should be 100% UV resistant, as well as polarized (unless you are flying aircraft), and should wrap around your face so that light cannot get around the side of the frame. Test if they are polarized by looking at a computer screen with them on. If the light intensity from the screen changes as you tilt your head at various angles, then the lenses are polarized. Polarization test cards are also available which reveal hidden objects if viewed through a polarized lens. It's not so easy to test whether the lenses block UV light. Cheap UV meters are available (less than $10) on places such as Aliexpress. Even better is to have the lenses tested at your local optometrist.
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Main > Health > Optics/glasses/spectacles
If you don't have your glasses and you are near-sighted (can't focus on the distance) then you can use the camera on your phone to focus on what is distant, and view the image on your phone.
thesource (378)
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Main > Health > Optics/glasses/spectacles > Sunglasses
Different color lenses are for different purposes:
- Black, gray, smoke, or mirror lenses are best for bright conditions. The color that you see through the lens remain similar to what you normally see, though will be darkened.
- Brown is a good all-round lens, which is okay for bright light, but will also improve contrast, clarity, and depth perception.
- Amber or orange lenses are not the best for bright days, but can help increase contrast on cloudy or overcast days, as they filter out blue light. Blue light diffuses easily, decreasing the contrast of what one sees.
- Yellow lenses can increase clarity in foggy and hazy conditions. These also work by blocking blue light. These are not designed for bright days.
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