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An eye chart is a chart used to measure visual acuity comprising lines of optotypes in ranges of sizes. Optotypes are the letters or symbols shown on an eye chart. [ 1 ] Eye charts are often used by health care professionals, such as optometrists , physicians and nurses , to screen persons for vision impairment .
Human proportions marked out in an illustration from a 20th-century anatomy text-book. Hermann Braus, 1921 Drawing of a human male, showing the order of measurement in preparation for a figurative art work (Lantéri, 1903) [1] It is usually important in figure drawing to draw the human figure in proportion.
In 1961, Danish Egyptologist Erik Iverson described a canon of proportions in classical Egyptian painting. [2] This work was based on still-detectable grid lines on tomb paintings: he determined that the grid was 18 cells high, with the base-line at the soles of the feet and the top of the grid aligned with hair line, [3] and the navel at the eleventh line. [4]
Eyeshades. Green eyeshades or dealer's visors are a type of visor that were worn most often from the late 19th century to the mid-20th century by accountants, telegraphers, copy editors, and others engaged in vision-intensive, detail-oriented occupations to lessen eye strain [1] due to early incandescent lights and candles, which tended to be harsh (the classic banker's lamp had a green shade ...
The first half of the 18th century saw British optician Edward Scarlett perfect temple eyeglasses which would rest on the nose and the ears. The innovations presented by Scarlett would not only spark some to look at aesthetic customization of eyewear for fashion within Europe but also lead Benjamin Franklin to invent bifocals in colonial America. [12]
A Snellen chart is an eye chart that can be used to measure visual acuity. Snellen charts are named after the Dutch ophthalmologist Herman Snellen who developed the chart in 1862 as a measurement tool for the acuity formula developed by his professor Franciscus Cornelius Donders .
Beer bottles of different colors. Glass coloring and color marking may be obtained in several ways.. by the addition of coloring ions, [1] [2]; by precipitation of nanometer-sized colloids (so-called striking glasses [1] such as "gold ruby" [3] or red "selenium ruby"), [2] Ancient Roman enamelled glass, 1st century, Treasure of Begram
Man with glasses. A woman with glasses. Glasses, also known as eyeglasses, spectacles, or colloquially as specs, 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.