Eye glasses consist of frames that contain lens. These lens then provide vision correction for those with sight problems as well as protection from UV light. Historical eye glasses include a lorgnette, scissors glasses, monocle and pince-nez. Modern glasses will provide support in the form of pads by the ears and nose. Commonly eye glass frames are made of plastic or metal and the lenses are made of glass.
Your eyeglasses will have a frame made of plastic or metal and lenses that are composed of many different materials. Besides glass eyeglass lenses are made of plastic, polycarbonate and CR-39.
Synthetic eyeglasses can also filter out UV light to protect your eyes, are very durable and can transmit visible light much better the glass eyeglasses. Some of the newest materials for eyeglasses, one being izon, can even correct higher eye aberrations which could be difficult to fix.
The latest in eyeglasses include lenses that have anti-reflective coatings, hydrophobic coatings and are scratch resistant. Anti-reflective lenses make it much more easier to see at night and hydrophobic coatings make cleaning your eyeglasses very easy. Eyeglasses with CR-39 lenses are the most popular as this material cannot be scratched, protects against infrared and UV light and are very lightweight.
Most eye glasses are used to correct vision problems. These eyeglasses achieve this in a way so that when you combine the lenses in your glasses with the lenses in your eyes you can see clearly. Eyeglasses can be used to correct farsightedness, nearsightedness and astigmatism. Most vision problems will require prescription glasses which require and eye exam. However very mild forms of farsightedness can be corrected using over the counter reading glasses.
Sunglasses can be obtained as prescription or non-prescription lenses. The main purpose of sunglasses is to protect your eyes from very bright light and UV light. The newest types of eyeglasses are photochromatic so that when more UV light hits them they automatically darken to protect your eye. Sunglasses also have light polarization features. This polarization removes glare so that you can see when reflected light and glare might normally be a problem.
Sunglasses have many different colored lens. Yellow lenses can be used to improve your depth perception and color contrast. Brown lenses tend to cause color distortion and are used by golfers. Sunglasses that are green, purple or blue do not enhance your vision at all. Many times sunglasses are only worn for aesthetic reasons as a person may want to hide their eyes. In this case mirror shades are very popular.
Other types of eyeglasses include 3D glasses that create a three dimensional illusion, reading glasses that are general for very mild cases and can be purchased over the counter, bifocals which have two focus lenses, general for near sight at the bottom and far sight on the top, trifocals have three different lenses for multiple focus and progressive eyeglasses that are multi focus but do not have any lines and have a smooth transition between different focal lenses.