Editing Presbyopia (section)

==Signs and symptoms==
The first symptoms most people notice are difficulty reading fine print, particularly in low light conditions, [[asthenopia|eyestrain]] when reading for long periods, blurring of near objects or temporarily blurred vision when changing the viewing distance. Many extreme presbyopes complain that their arms have become "too short" to hold reading material at a comfortable distance.{{cn|date=July 2022}}

Presbyopia, like other focal imperfections, becomes less noticeable in bright sunlight when the pupil becomes smaller.<ref name="MarquetteEye">{{cite web|url=http://www.marquetteeye.com/patientinfo/presbyopia.html|title=Presbyopia: Patient Information|publisher=Eye Associates of Marquette|location=[[Marquette, MI]]|year=2008|access-date=2010-10-31|url-status=dead|archive-url=https://web.archive.org/web/20081202175115/http://www.marquetteeye.com/patientinfo/presbyopia.html|archive-date=2 December 2008}}</ref> As with any lens, increasing the [[F-number|focal ratio]] of the lens increases depth of field by reducing the level of blur of out-of-focus objects (compare the effect of aperture on [[depth of field]] in [[photography]]).

The onset of presbyopia varies among those with certain professions and those with [[miotic]] [[pupil]]s.<ref name="Garcia">{{cite journal |pmid=12410405 |date=Nov 2002 |last1=García Serrano |first1=JL |last2=López Raya |last3=Mylonopoulos Caripidis |title=Variables related to the first presbyopia correction |volume=77 |issue=11 |pages=597–604 |issn=0365-6691 |journal=Archivos de la Sociedad Española de Oftalmología |url=http://www.oftalmo.com/seo/2002/11nov02/03.htm |format=Free full text |first2=R |first3=T |url-status=live |archive-url=https://web.archive.org/web/20111007032318/http://www.oftalmo.com/seo/2002/11nov02/03.htm |archive-date=7 October 2011}}</ref> In particular, farmers and homemakers seek correction later, whereas service workers and construction workers seek correction earlier. [[Scuba divers]] with interest in [[underwater photography]] may notice presbyopic changes while diving before they recognize the symptoms in their normal routines due to the near focus in low light conditions.<ref name="pmid22692711">{{cite journal |author=Bennett QM |title=New thoughts on the correction of presbyopia for divers |journal=Diving Hyperb Med |volume=38 |issue=2 |pages=163–164 |date=June 2008 |pmid=22692711 |url=http://archive.rubicon-foundation.org/10206 |access-date=2013-04-19 |url-status=usurped |archive-url=http://archive.wikiwix.com/cache/20130419204149/http://archive.rubicon-foundation.org/10206 |archive-date=19 April 2013}}</ref>

===Interaction with myopia===
People with low [[myopia|near-sightedness]] can read comfortably without eyeglasses or contact lenses even after age forty, but higher myopes might require two pairs of glasses (one for distance, one for near), bifocal, or progressive lenses. However, their myopia does not disappear and the long-distance visual challenges remain. Myopes considering [[refractive surgery]] are advised that surgically correcting their nearsightedness may be a disadvantage after age forty, when the eyes become presbyopic and lose their ability to [[accommodation (eye)|accommodate]] or change focus, because they will then need to use glasses for reading. Myopes with low [[Astigmatism (eye)|astigmatism]] find near vision better, though not perfect, without glasses or contact lenses when presbyopia sets in, but the more astigmatism, the poorer the uncorrected near vision.{{cn|date=July 2022}}

A surgical technique offered is to create a "reading eye" and a "distance vision eye", a technique commonly used in contact lens practice, known as [[monovision]]. Monovision can be created with contact lenses, so candidates for this procedure can determine if they are prepared to have their corneas reshaped by surgery to cause this effect permanently.{{cn|date=July 2022}}