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Euphrasia, or eyebright, is a genus of about 215 species of herbaceous flowering plants in the family Orobanchaceae (formerly included in the Scrophulariaceae), with a cosmopolitan distribution. They are hemiparasitic on grasses and other plants.
Euphrasia stricta, the drug eyebright, is an annual forb in the genus Euphrasia. [1]It has been introduced in northeastern North America, where it is found in New England (except Connecticut), New York, Pennsylvania, Nova Scotia, New Brunswick, Prince Edward Island, Ontario, Quebec, the upper peninsula of Michigan, northern Wisconsin, Minnesota and Illinois. [2]
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 .
Other sources restrict the use of the word to temporary, reversible vision loss, distinguishing it from permanent blindness in a hierarchy of effects: "when the eye perceives bright light one of four reactions may take place. These are, in order of increasing brightness: dazzle, after image formation, flash blindness, and irreversible damage.
Euphrasia vigursii, also known by its common names of Vigur's eyebright [3] or Cornish eyebright, [4] is an endangered annual of the eyebright family which is endemic to Devon and Cornwall. [ 5 ] [ 6 ] [ 7 ] It is a facultative hemiparasite and needs open conditions and regular grazing of larger shrubs and grasses to grow.
Visual acuity with Near chart without correctors Visual acuity with eye chart at Near 15.7 inches (400 mm) and without (sc: Latin sine correctore) correctors (spectacles); Ncc is with (cc: Latin cum correctore) correctors. See Visual_acuity#Legal_definitions: VA OS Left visual acuity VA OD Right visual acuity VDU Visual display unit VF Visual field
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 ...
The largest letter on an eye chart often represents an acuity of 6/60 (20/200), the value that is considered "legally blind" in the US. Many individuals with high myopia cannot read the large E without glasses, but can read the 6/6 (20/20) line or 6/4.5 (20/15) line with glasses. By contrast, legally blind individuals have a visual acuity of 6/ ...