Difference between revisions of Diopters
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Diopter is a measure of the power of a [[lens]] (or mirror). It is equal to 1/[[focal length]] in meters. In EM we refer to the [[cm measurement]] to calculate diopters needed to correct [[refraction]] of the eye. If you can see 50cm clearly your diopters will be 1/0.5=2 diopters. | Diopter is a measure of the power of a [[lens]] (or mirror). It is equal to 1/[[focal length]] in meters. In EM we refer to the [[cm measurement]] to calculate diopters needed to correct [[refraction]] of the eye. If you can see 50cm clearly your diopters will be 1/0.5=2 diopters. | ||
Lenses in series add their powers : if you're wearing -2 diopter contacts ([[vertex distance|adjusted for glasses strength]]) and put +1 diopter reading glasses over the contacts you're in effect wearing -1 diopters. | |||
A lens with a negative diopter sign compensates for [[nearsightedness]] while a lens with a positive diopter sign compensates for [[farsightedness]] | A lens with a negative diopter sign compensates for [[nearsightedness]] while a lens with a positive diopter sign compensates for [[farsightedness]]. | ||
Approximate categorizations of myopia by lens power: | Approximate categorizations of myopia by lens power: | ||