101:
394:
486:. If both surfaces of the lens are curved, consider their curvatures as positive toward the lens and add them. This gives approximately the right result, as long as the thickness of the lens is much less than the
578:
308:(nearsighted) person requires a basic correction of, say, −2 dioptres to restore normal distance vision, might then make a further prescription of 'add 1' for reading, to make up for lack of
221:
are placed close together their powers approximately add. Thus, a thin 2.0-dioptre lens placed close to a thin 0.5-dioptre lens yields almost the same focal length as a single 2.5-dioptre lens.
198:
metre. A flat window has an optical power of zero dioptres, as it does not cause light to converge or diverge. Dioptres are also sometimes used for other reciprocals of distance, particularly
674:
300:
optical power, rather than doing a detailed analysis of the entire optical system (the eye and the lens). Optical power can also be used to adjust a basic
694:
Monoyer, F. (1872). "Sur l'introduction du système métrique dans le numérotage des verres de lunettes et sur le choix d'une unité de réfraction".
740:
255:
The idea of numbering lenses based on the reciprocal of their focal length in metres was first suggested by
Albrecht Nagel in 1866. The term
584:
This is approximately the magnification observed when a person with normal vision holds the magnifying glass close to his or her eye.
343:
is about 11 to 16 dioptres at age 15, decreasing to about 10 dioptres at age 25, and to around 1 dioptre above age 60.
232:, it has not been included in the standard, so that there is no international name or symbol for this unit of measurement—within the
870:
839:
537:
676:
The history & traditions of the
Moorfields Eye Hospital: one hundred years of ophthalmic discovery & development
657:
441:
423:
241:
336:
805:
419:
779:
903:
593:
312:(ability to alter focus). This is the same as saying that −1 dioptre lenses are prescribed for reading.
233:
225:
339:. This results in increased convexity of the lens which in turn increases the optical power of the eye. The
908:
487:
199:
240:(m). However most languages have borrowed the original name and some national standardization bodies like
747:
340:
680:
466:
with a radius of 1/2 metre has a curvature of 2 dioptres. If the curvature of a surface of a lens is
365:
346:
751:
415:
404:
31:
17:
623:
511:
408:
372:(nearsightedness). Typical glasses for mild myopia have a power of −0.50 to −3.00 dioptres.
217:
has the object distance, image distance, and focal length all as reciprocals. Additionally, when
173:
104:
Illustration of the relationship between optical power in dioptres and focal length in metres.
358:
301:
289:
319:
accounts for approximately two-thirds of this refractive power (about 40 dioptres) and the
8:
714:
471:
328:
309:
141:
137:
315:
In humans, the total optical power of the relaxed eye is approximately 60 dioptres. The
862:
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The main benefit of using optical power rather than focal length is that the
161:
157:
880:
849:
236:, this unit for optical power would need to be specified explicitly as the
207:
185:
177:
323:
contributes the remaining one-third (about 20 dioptres). In focusing, the
100:
373:
245:
30:
This article is about the unit of measure in optics. For other uses, see
628:
603:
361:
354:
831:
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608:
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455:
357:(the limited accommodation of advancing age) to read at close range.
350:
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for reading. Thus an eye care professional, having determined that a
268:
218:
393:
783:
650:
Spectacles and Other Vision Aids: A History and Guide to
Collecting
613:
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have positive dioptric value and are generally used to correct
316:
305:
165:
181:
297:
118:
573:{\displaystyle V=0.25\ \mathrm {m} \times \varphi +1}
540:
380:
using lenses graded in steps of 0.25 dioptres.
368:have negative dioptric value and generally correct
244:specify a unit name (dioptrie, dioptria, etc.). In
572:
830:. SPIE Field Guides vol. FG01. Bellingham, Wash:
454:The dioptre can also be used as a measurement of
890:
184:. For example, a 3-dioptre lens brings parallel
501:
284:The fact that optical powers are approximately
856:
825:
422:. Unsourced material may be challenged and
364:are rated at +1.00 to +4.00 dioptres.
266:in 1872, based on earlier use of the term
773:
771:
647:
442:Learn how and when to remove this message
353:(farsightedness) or to allow people with
803:
738:
99:
693:
672:
279:
14:
891:
768:
712:
624:Prism correction § Prism dioptres
857:Hecht, Eugene; Alfred, Zając (1987).
804:Palanker, Daniel (October 28, 2013).
512:Magnifying glass § Magnification
156:. It is normally used to express the
420:adding citations to reliable sources
387:
27:Unit of measurement of optical power
808:. American Academy of Ophthalmology
462:measured in metres. For example, a
224:Though the dioptre is based on the
24:
777:
741:"Measuring Vision and Vision Loss"
554:
25:
920:
828:Field Guide to Geometrical Optics
673:Collins, Edward Treacher (1929).
780:"Clinical optics and refraction"
527:is related to its optical power
392:
861:(2nd ed.). Reading, Mass:
806:"Optical Properties of the Eye"
719:La médecine à Nancy depuis 1872
458:equal to the reciprocal of the
335:transferred to the lens by the
797:
732:
706:
687:
666:
648:Rosenthal, J. William (1996).
641:
490:of one of the surfaces. For a
296:as a simple correction to the
13:
1:
634:
234:international system of units
826:Greivenkamp, John E (2004).
502:Relation to magnifying power
478:, the optical power is φ = (
383:
119:
7:
587:
10:
925:
748:Smith-Kettlewell Institute
681:H. K. Lewis & Co. Ltd.
505:
494:the optical power is φ = 2
341:amplitude of accommodation
29:
84:
80:
62:
54:
46:
41:
782:. Eyeweb. Archived from
327:contracts to reduce the
32:Diopter (disambiguation)
259:was proposed by French
739:Colenbrander, August.
696:Annales d'Oculistiques
652:. Norman. p. 32.
574:
219:relatively thin lenses
105:
575:
506:Further information:
290:eye care professional
188:of light to focus at
103:
904:Units of measurement
715:"Monoyer, Ferdinand"
538:
416:improve this section
337:suspensory ligaments
280:In vision correction
252:is frequently used.
148:, equivalent to one
909:Non-SI metric units
488:radius of curvature
472:index of refraction
138:unit of measurement
75:... is equal to ...
570:
200:radii of curvature
106:
92:
86:
872:978-0-201-11609-0
841:978-0-8194-5294-8
552:
452:
451:
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294:corrective lenses
264:Ferdinand Monoyer
215:thin lens formula
170:physical quantity
146:reciprocal length
126:American spelling
98:
97:
63:Conversions
16:(Redirected from
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525:magnifying glass
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518:magnifying power
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396:
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378:refractive error
376:usually measure
359:Over the counter
321:crystalline lens
197:
196:
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155:
150:reciprocal metre
122:
121:
114:British spelling
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362:reading glasses
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274:Johannes Kepler
261:ophthalmologist
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180:, expressed in
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28:
23:
22:
15:
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5:
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863:Addison–Wesley
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778:Najjar, Dany.
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366:Concave lenses
325:ciliary muscle
281:
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786:on 2008-03-23
785:
781:
774:
772:
757:on 2014-12-04
753:
749:
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735:
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709:
702:. Paris: 101.
701:
698:(in French).
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659:9780930405717
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508:Magnification
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401:This section
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347:Convex lenses
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342:
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310:accommodation
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292:to prescribe
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258:
253:
251:
247:
243:
239:
238:inverse metre
235:
231:
230:metric system
227:
222:
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216:
211:
209:
208:optical beams
205:
201:
187:
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172:equal to the
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168:, which is a
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158:optical power
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83:
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53:
50:optical power
49:
45:
40:
37:
33:
19:
858:
827:
810:. Retrieved
799:
788:. Retrieved
784:the original
759:. Retrieved
752:the original
734:
723:. Retrieved
718:
708:
699:
695:
689:
683:p. 116.
675:
668:
649:
643:
583:
523:of a simple
517:
515:
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483:
479:
475:
467:
453:
438:
432:January 2015
429:
414:Please help
402:
374:Optometrists
345:
314:
302:prescription
283:
267:
256:
254:
249:
223:
212:
178:focal length
133:
129:
117:
109:
107:
74:
69:
58:dpt, D
47:Unit of
36:
721:(in French)
713:Thomas, C.
594:Astigmatism
288:enables an
248:the symbol
246:vision care
154:1 dpt = 1 m
68:1 dpt
893:Categories
812:2017-10-16
790:2008-03-25
761:2009-07-10
725:2011-04-26
679:. London:
635:References
629:Vertometer
604:Lens clock
355:presbyopia
174:reciprocal
164:or curved
128:), symbol
619:Optometry
609:Lensmeter
599:Dioptrics
562:φ
559:×
456:curvature
403:does not
384:Curvature
351:hyperopia
269:dioptrice
142:dimension
881:13761389
850:53896720
588:See also
470:and the
286:additive
204:vergence
202:and the
88:SI units
18:Diopters
424:removed
409:sources
329:tension
257:dioptre
193:⁄
176:of the
136:, is a
120:diopter
110:dioptre
42:dioptre
899:Optics
879:
869:
859:Optics
848:
838:
656:
614:Optics
551:
492:mirror
464:circle
460:radius
370:myopia
333:stress
317:cornea
306:myopic
182:metres
166:mirror
70:in ...
55:Symbol
755:(PDF)
744:(PDF)
298:eye's
160:of a
140:with
116:) or
877:OCLC
867:ISBN
846:OCLC
836:ISBN
832:SPIE
654:ISBN
548:0.25
516:The
510:and
482:− 1)
407:any
405:cite
186:rays
162:lens
531:by
474:is
418:by
331:or
272:by
242:DIN
206:of
144:of
132:or
130:dpt
94:1 m
895::
875:.
865:.
844:.
834:.
770:^
746:.
717:.
700:68
498:.
276:.
226:SI
210:.
152:,
108:A
883:.
852:.
815:.
793:.
764:.
728:.
662:.
580:.
568:1
565:+
555:m
545:=
542:V
529:φ
521:V
496:C
484:C
480:n
476:n
468:C
445:)
439:(
434:)
430:(
426:.
412:.
250:D
228:-
195:3
191:1
134:D
124:(
112:(
34:.
20:)
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