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Eyeglass prescription. Using a phoropter to determine a prescription for eyeglasses. An eyeglass prescription is an order written by an eyewear prescriber, such as an optometrist, that specifies the value of all parameters the prescriber has deemed necessary to construct and/or dispense corrective lenses appropriate for a patient.
Prism dioptres. Prism correction is commonly specified in prism dioptres, a unit of angular measurement that is loosely related to the dioptre. Prism dioptres are represented by the Greek symbol delta (Δ) in superscript. A prism of power 1 Δ would produce 1 unit of displacement for an object held 100 units from the prism. [2]
The prism cover test ( PCT) is an objective measurement and the gold standard in measuring strabismus, i.e. ocular misalignment, or a deviation of the eye. [1] It is used by ophthalmologists and orthoptists in order to measure the vertical and horizontal deviation and includes both manifest and latent components. [1]
Mobile phones use geographic area codes (two digits): after that, all numbers assigned to mobile service have nine digits, starting with 6, 7, 8 or 9 (example: 55 15 99999–9999). 90 is not possible, because collect calls start with this number. [5] xx 7: xx 8: xx 9: British Indian Ocean Territory +246: 380 7 387 British Virgin Islands +1: 284: 10
Landolt C. Lea test. logMAR chart. 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.
These letter assignments have been used for multiple purposes. Originally, they referred to the leading letters of telephone exchange names.In the mid-20th century United States, before the switch to All-Number Calling, telephone numbers had seven digits, including a two-digit prefix which was expressed in letters rather than digits, e.g.; KL5-5445.
Area codes 514, 438, and 263. Area codes 514, 438, and 263 are telephone area codes of the North American Numbering Plan (NANP) for Montreal and most of its on-island suburbs, specifically the Island of Montreal and Île Perrot in the Canadian province of Quebec . Area code 514 was one of the original North American area codes assigned by AT&T ...
Prism (optics) A familiar dispersive prism. An optical prism is a transparent optical element with flat, polished surfaces that are designed to refract light. At least one surface must be angled — elements with two parallel surfaces are not prisms. The most familiar type of optical prism is the triangular prism, which has a triangular base ...