What Do You Know About Eyeglasses?

Eyeglasses, defined in Wikipedia, are frames bearing lenses worn in front of the eyes. They are formerly used for vision correction; later for eye protection, either from foreign matter or from harmful rays. In fact, they can be a major part of person image and expression as well.

Eyeglasses are thought to be one of the most important invention of mankind history, because without them, scientists may not be able to do precision researches and bring so many discoveries to us; without them, we ordinary people with eyesight problems will never observe the beautiful world around us clearly.

Since eyeglasses are so important to us, what do you know about them?

Eyeglasses emerge earlier than most of us imagine. The first recorded use of corrective lenses may have taken place around 1^st Century AD in Rome, while the first pair of wearable eyeglasses was invented around 1284 in Italy by Salvino D'Armate. Since then, eyeglasses began their evolution, from those without legs to with legs; from those with glass lenses to high index plastic lenses; from those plastic frames to titanium frames, etc..

Then with different requirements of eyeglasses of different people, diverse types of eyeglasses are then invented.

Corrective glasses: the original corrective glasses are used to correct refractive errors of the eye--myopia, hyperopia or astigmatism, etc.. This should the most common type for people in their daily lives.

Safety glasses: they are mostly used by athletes or sports lovers, helping them prevent foreign bodies entering eyes; what's more, for the fact that there is a greater chance for this kind of glasses to get broken and debris may fly into eyes, safety glasses are usually made with shatter-resistant plastic lenses.

Sunglasses: sunglasses provide protection against harmful rays from the sun, so as to reduce or stop the possibility of the emergence of kinds of eye disease. Additionally, nowadays sunglasses can be of both prescription or non-prescription, that is to say, if you are a person with eyesight problems who has to wear corrective glasses, you can also wear prescription sunglasses which both prevent harmful rays and provide a clear vision.

Presbyopia glasses: they include bifocals, trifocals and progressive lenses. The first two lenses are the traditional ones which have only two or three distinct horizontal viewing area, which are easily to make the wearers dizzy for the sharp transition between the focal points. Unlike the two, the last lenses give a smooth transition, providing the wearers a comfortable feeling.

3D glasses: they are specially designed for people to watch 3D movies. Due to the illusion of three dimensions on a two dimensional surface, 3D glasses can offer each eye with different visual information, making the image more real.

Of course there are many other glasses for different usages, for example glasses for watching the solar eclipse.

As for eyeglass styles, they are of a great variety, ranging from rimless glasses to boxy glasses. At present the most in style is those with thick, black and boxy or round frames, in a kind of restoring ancient way. In street, if you keep an eye on the passersby, you will find a lot of them wearing thick boxy or round glasses of different colors, and some of them even just wear glass frames without lenses, just for fashion.

Eye Exercise Tips For You----take Care Of Your Eyes

Sit comfortably on a chair. Rub your hands together until they feel warm. Close your eyes and cover them lightly with your cupped palms. Avoid applying pressure on your eyeballs. Place your palms so that the nose remains uncovered, and the eyes remain behind the slight hollow of the palms. Make sure that no light rays enter the eyes, and leave no gaps between fingers or between the edge of the palms and the nose. You may still see other lingering traces of colors. Imagine deep blackness and focus on the blackness. Take deep breaths slowly and evenly, while thinking of some happy incident; or visualize a distant scene. After your eyes see nothing but blackness, remove your palms from your eyes. Repeat the palming for 3 minutes or more.
Close your eyes tightly for 3-5 seconds, and then open them for 3-5 seconds. Repeat this 7 or 8 times.
Close your eyes and massage them with circular movements of your fingers for 1-2 minutes. Make sure you press very lightly; otherwise, you could hurt your eyes.
Press three fingers of each hand against your upper eyelids, and hold them there for 1-2 seconds, then release. Repeat 5 times.
Sit and relax. Roll your eyes clockwise, then counter-clockwise. Repeat 5 times, and blink in between each time.
Sit about 6 inches (150 mm) from the window. Make a mark on the glass at your eye level (a small sticker, black or red, would be perfect). Look through this mark and focus on something far away for 10-15 seconds; then focus on the mark again.
Hold a pencil in front of you at arm's length. Move your arm slowly to your nose, and follow the pencil with your eyes until you can keep it in focus. Repeat 10 times.
Look in front of you at the opposite and pretend that you are writing with your eyes, without turning your head. It may seem difficult at first, but with a bit of practice it is really fun. The bigger the letters, the better the effect.
Imagine that you are standing in front of a really big clock. Look at the middle of the clock. Then look at any hour mark, without turning your head. Look back at the center. Then look at another hour mark. Do this at least 12 times. You can also do this exercise with your eyes closed.
Focus on a distant object (over 150 feet or 50 m away) for several seconds and slowly refocus your eyes on a nearby object (less than 30 feet or 10 m away) that's in the same direction. Focus for several seconds and go back to the distant object. Do this 5 times.
Focus on an object in the distance (as far as possible) with a low contrasting background. Do this for a few minutes every half hour or so. This does not improve your vision, nor does any other technique. It can, however, maintain your best eyesight level during the day and prevent significant further vision deterioration.
Make up and down eye movements starting from up to to down. Do this 8 times. Then do the side to side eye movement, starting from left to right. Repeat this 8 times. Make sure not to add pressure to your eyes! It only worsen your vision!