View source for Asthenopia

{{DiseaseDisorder infobox |
  Name        = Asthenopia |
  ICD10       = H53.1 |
  ICD9        = {{ICD9|368.13}} |
}}
{{SI}}



'''Asthenopia''' or eye strain is an [[ophthalmology|ophthalmological]] condition that manifests itself through nonspecific [[symptom]]s such as [[fatigue]], red eyes, eye strain, pain in or around the eyes, blurred vision, [[headache]] and occasional [[diplopia|double vision]]. Symptoms often occur after reading, computer work, or other activities that involve tedious visual tasks. 

When concentrating on a visually intense task, such as continuously focusing on a book or computer monitor, the inner eye muscles may tighten, which can cause the eyes to get irritated, dry, and uncomfortable. Giving the eyes a chance to focus on a distant object at least once an hour usually alleviates the problem. Small font sizes exacerbate the strain if they cause unconscious squinting or straining to focus.

On a computer, a [[Cathode ray tube|CRT]] with a low refresh rate (less than 70 Hz) can cause similar problems because of the flickering image.  Aging CRTs also often go slightly out of focus, and this can also cause eye strain.  [[Liquid crystal display|LCDs]] do not go out of focus and are less susceptible to visible flicker.  Higher refresh rates and larger font sizes are worthwhile when addressing eyestrain problems.

==Causes==
Sometimes, [[asthenopia]] can be due to specific visual problems, such as uncorrected [[refraction error]]s or [[binocular vision]] problems like [[accommodative insufficiency]] or [[heterophoria]].

== See also ==
{{wiktionary|asthenopia}}
*[[Computer vision syndrome]]
*[[Eye examination]]
*[[Vision therapy]]
*[[Astigmatism#Ophthalmic astigmatism|Astigmatism]]

==External links==
*[http://www.eyesite.ca/english/public-information/eye-facts/reducing.htm Reducing Eye Strain]
*[http://www.nei.nih.gov National Eye Institute]
*[http://www.3dtoast.com/ GoogleDark google thats easier on the eyes!]

{{Eye pathology}}



[[de:Asthenopie]]
[[pl:Astenopia]]


[[Category:Ophthalmology]]
[[Category:Medical signs]]
[[Category:Signs and symptoms]]


{{WikiDoc Help Menu}}
{{WikiDoc Sources}}