The first glasses

It is unknown who invented present-day glasses. During the archeological dig of Troy and on Crete were found optic lenses made out of rock crystal, which theoretically could be used as optic device for vision correction. According to legend, Rome imperator Nero used optical lens made out of emerald for vision correction. Present-day glasses (https://www.buyglassesusa.com/) are 600 years old. Just from the end of XIII century glass lenses for vision correction were mentioned.

Glasses – what are they?

Glasses are an optical device for vision correction.  They consist of glasses lenses and a frame. It might seem- everything is simple, but in real to pick up good glasses that will fit you is quite difficult task. Let us assume that you got a chance to be diagnosed by a good specialist and you got correct receipt for glasses vision correction. Then, what you should know while buying glasses?

Typical mistakes during glasses choosing.

The typical mistake while choosing glasses is that attention is pay on frame choosing. Most of people do not even think about the lenses which will be put onto frame. They believe that frame is the glasses. Unfortunately, mass of people consider glasses as fancy goods, but not as medical goods. Glasses are product to sell everywhere besides the special institution. You can by sunglasses, for example, in clothes shop. While buying such glasses attention is paid on the frame appearance. While optic quality is not issue to discuss. What happens if “incorrect” glasses, which does not comply with optic characteristics (diopter, spacing on centers ), were bought? Or if glasses lenses were made out of low quality material? Then process of habituation is initiated. While habituation an organism tries to compensate optical distortion (aberrations), which results in eye overwork, headache and further deterioration of vision.

 -    Glasses lenses material. At  present lenses picking up lies between glass and plastic. Definitely entire preference cannot be given neither to glass, no to plastic.  Plastic, as material, much more softer than glass, and more open to injury. But all modern plastic lenses are produced with strengthening cover, which makes them resistant to scratches as glass.

-    Advantages of plastic lenses is their lightness. Specific weight of optical plastic is two times less then glass, that’s why your plastic lenses glasses will be much lighter. They are less danger, besides. Plastic gives more opportunities for handling, lenses coloring, in particular.

-     Advantages of glass lenses is refraction coefficient (index), which is higher than in plastic. Besides, durability of glass is higher (except for impact resistance). These mean that quality glass lenses with equal diopters  will be  thinner and more plane, than plastic.

-    Anti-reflex lenses cover is a special technology, much improving optical features of glasses lens. Anti-reflex increases lenses transparence for 8-10 %. at the cost of better transparence and absence of visual noises lenses with anti-reflex much more comfort for eyes and produce  less  ocular fatigue. In darkness lenses with anti-reflex allow to see better while driving the car.Thus, glasses choosing should be started from lenses choosing, eslecially, if you need correction of marked malfunktions with many diopters.