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This specifies the part of the prescription designed primarily to improve far vision. In a bifocal lens, this generally indicates what is to be placed in the top segment. NV is an abbreviation for near vision. This may represent a single-vision lens prescription to improve near work, or the reading portion of a bifocal lens.
In glasses with powers beyond ±4.00D, the vertex distance can affect the effective power of the glasses. [4] A shorter vertex distance can expand the field of view, but if the vertex distance is too small, the eyelashes will come into contact with the back of the lens, smudging the lens and causing annoyance for the wearer.
In some studies, bifocal and progressive lenses have not shown differences in altering the progression of myopia compared to placebo. [ 95 ] [ 102 ] In the United States, the Food and Drug Administration (FDA) has approved myopia control contact lenses such as CooperVision’s MiSight and Johnson & Johnson Vision’s Acuvue Abiliti.
The 1.1"/75 caliber gun was an American anti-aircraft weapon of World War II, used by the United States Navy. [3] The name means that it had a bore diameter of 1.1 in (28 mm) and barrel caliber of 75 (1.1 inches × 75 = 82.5 in (2.1 m)). The gun was designed to replace the M2 Browning and four barrels were required to duplicate the rate of fire.
The human eye is a sensory organ in the visual system that reacts to visible light allowing eyesight.Other functions include maintaining the circadian rhythm, and keeping balance.
Illustration of the relationship between optical power in dioptres and focal length in metres. A dioptre (British spelling) or diopter (American spelling), symbol dpt or D, is a unit of measurement with dimension of reciprocal length, equivalent to one reciprocal metre, 1 dpt = 1 m −1.
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