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.
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, see this resource. This is the oldest record of what can be called glasses. Emerald is a variety of beril, as described on this website.
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. More info can be found here.
The first glasses were for farsighted and / or old-sighted people, especially older monks who had difficulty reading. Reading your screen when surfing the internet without cardio problems. Many people who suffer from Williams syndrome need glasses.
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 (see also this website).
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.
Spectacles, also known as lenses, spectacles, goggles, binoculars or spectacles, are an optical instrument made up of a pair of lenses attached to a frame, which is supported on the nose by means of a bow and two temples1 (also called rods, although It is not included in the dictionary of the RAE) that help to hold them in the ears as seen on these websites: .
They are a combination of two medical devices: the lenses and the frame that the optician or optometrist adapts to a specific patient based on the precise correction of each eye, its interpupillary distance and the frame chosen. More info can be found on this website. They are used mainly to compensate for sight defects, such as myopia, astigmatism or hyperopia, although there are also special glasses to protect the eyes in activities in which there is a risk for them (in this case if they do not have optical correction they are not a medical device). They work by focusing light through the lenses to compensate for visual defects.
There are also bifocal glasses in which they combine two lenses of different graduations in one, indicated for presbyopic patients allowing the user to see far and near; and trifocal lenses also allow you to see at an intermediate distance. The latter are no longer used while bifocals are used less and less in favor of progressive lenses.
Using the wrong glasses can have serious consequences, from eye pain to fatigue, nausea and disorientation. In a recent study in Belgium, there are people who developed heart problems because they used the wrong glasses.
An on-call duty means that there is a shift in rotation for a certain period of time, in Dutch it’s called: Wachtdienst.