Glasses are an optical instrument that is worn in front of the eyes and compensates for the ametropia (refraction error) of the eye, so that the wearer sees sharper. In addition to refractive errors, some other deviations can also be corrected with glasses, such as strabismus, old-sightedness, and the like. Furthermore, glasses can be used as eye protection, such as sunglasses, various types of safety glasses, and the like.

Glasses consist of the frame and the lenses (optical lenses), which can be made of glass or plastic.

History

The word ‘glasses’ comes from the mineral beril. That used to be used for grinding spectacle lenses.

Historians report that Emperor Nero watched gladiator fights through an emerald. It is believed that he did so because he was short-sighted. This is the oldest record of what can be called glasses. Emerald is a variety of beril.

Lenses used to improve eyesight have been reported in Italy since 1280. It is possible that at that time some kind of glasses were in use in the Arab world and in China, but the data on this are rather vague. It is possible that this invention was made in an undetermined place in the 13th century and then quickly spread over a large area.

The first glasses were for farsighted and / or old-sighted people, especially older monks who had difficulty reading.
Performance

Initially, the lens was in a stand, which was held by hand. The glasses clamped on the nose (squeeze glasses or pince-nez) with two glasses came a little later. Another version, best known from German officers, is the eyeglass, which was held in the folds of skin around the eye. Many of these glasses were worn on a string so that they could not fall. Glasses were also added with a stick on one side to hold, a so-called lorgnet.

The modern goggles, with springs (popularly referred to as legs) that attach the goggles behind the ears, date back to the early 18th century, and are first mentioned in England. These glasses were initially found to be ugly, and vain wearers preferred squeeze glasses or lorgnon, which were occasionally taken out. The advantage of modern glasses is that they can be worn permanently without leaving your hands.