Glasses, also known as eyepieces, are lens lenses embedded in the frame and worn in front of the eyes to improve vision, protect the eyes or for decoration. There are also special glasses online glasses usa for watching 3D stereoscopic images or virtual reality images.
Glasses online glasses usa can correct a variety of vision problems, including short-sightedness, long-sightedness, astigmatism, presbyopia, or strabismus, but they cannot cure or cure these problems. Other types of eyewear include goggles, sunglasses, swimming goggles, etc., which provide various protection for the eyes.
Modern glasses online glasses usa usually have a nose pad (nose bridge support) in the middle of the lens, and soft pads where the left and right arms rest on the ears, and there are also contact lenses.
The inventors of corrective glasses online glasses usa that fit the modern definition vary. In 1268, Roger Bacon first recorded lenses for optical purposes; 1280 is considered the year of the invention of eyeglasses[1], and magnifying glasses online glasses usa mounted in frames for reading have already appeared in Europe. In Europe, the earliest glasses online glasses usa appeared in Italy in the 13th century, introduced by Alessandro di Spina of Florence. The earliest portrait with glasses online glasses usa, Hugh of Provence, was painted by Tommaso da Modena in 1352. [2]
It is said that the Chinese "glasses" were first called 叆叇ài dài, which is the transliteration of the Arabic word for glasses online glasses usa (alunwainat)[3]. During the Jiajing period of the Ming Dynasty, Zhang Jing of the Ming Dynasty recorded in "Fangzhou Miscellaneous Records": "If the money is big, it is shaped like mica and is very thin. None of them can distinguish the fine script, but this thing is placed in the eyes, and the characters are doubled.” During the Wanli period, Tian Yiheng’s "Liu Qing Ri Zha·Kuu": "This is used to cover the eyes, the spirit is not scattered, and the strokes are trustworthy. The silk and silk couplets are used in the middle. It is tied to the back of the head. No one knows it, so I asked about it. Yu Ri said, 'This is Kuu'.
Spectacle lenses were made of crystal in the early days, and later made of glass. Some fiber lenses can block more ultraviolet rays than glass lenses, bringing better protection to the eyes. Coating the anti-scratch film on the plastic or fiber lens can make the lens have the same scratch resistance as the glass lens. Various coatings, such as waterproof and non-reflective coatings, can bring convenience and better visual effects to the wearer.
Spectacle lenses generally match the vision problem to be corrected. Simple myopia, hyperopia, and presbyopia require spherical lenses, while those with astigmatism need cylindrical lenses. Myopia requires concave lenses, while hyperopia and presbyopia require convex lenses.
The refractive strength of spectacle lenses is generally expressed in degrees. A diopter is equivalent to what most people call 100 degrees, that is, D 1.00 in non-Chinese-speaking countries (here D is Degree). The more severe the vision problem, the deeper the prescription and the thicker the lenses will be.
