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A person taking the test covers one eye from 6 metres or 20 feet away, and reads aloud the letters of each row, beginning at the top. The smallest row that can be read accurately indicates the visual acuity in that specific eye. The symbols on an acuity chart are formally known as "optotypes". Variation of Snellen chart with another letter ...
The eighth edition contains charts in English, Italian, French, German, and a calligraphic hand of the Latin script of German. [4] Snellen's charts became the global standard. [5] The most significant innovation was Snellen's use of what he called optotypes, specially designed characters generated on a 5x5 grid, rather than using standard fonts ...
Glasses, also known as eyeglasses or spectacles, are vision eyewear with clear or tinted lenses mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms, known as temples or temple pieces, that rest over the ears for support.
Modern glasses, the most dominant form of eyewear. Eyewear is a term used to refer to all devices worn over both of a person's eyes, or occasionally a single eye, for one or more of a variety of purposes. Though historically used for vision improvement and correction, eyewear has also evolved into eye protection, for fashion and aesthetic ...
Pince-nez (/ ˈ p ɑː n s n eɪ / or / ˈ p ɪ n s n eɪ /, plural form same as singular; [1] French pronunciation:) is a style of glasses, popular in the late 19th and early 20th centuries, that are supported without earpieces, by pinching the bridge of the nose.
Edward Scarlett (1688 – 1743 in London) was an English optician and instrument maker, who first invented an eyeglass frame with earhooks in 1727. This frame is held by the nose and ears, at times the glasses were called in contrast to the nasal cannula and temples because they had short straps that pressed on the temple.
It has been proposed that glass eye covers in hieroglyphs from the Old Kingdom of Egypt (c. 2686–2181 BCE) were functional simple glass meniscus lenses. [40] The so-called Nimrud lens, a rock crystal artifact dated to the 7th century BCE, might have been used as a magnifying glass, although it could have simply been a decoration. [41] [42 ...
An example of the Landolt C eye chart (also known as the Japanese eye chart). Numerous types of eye charts exist and are used in various situations. For example, the Snellen chart is designed for use at 6 meters or 20 feet, and is thus appropriate for testing distance vision, while the ETDRS chart is designed for use at 4 meters. [16]