Myopia in animals
{{For|myopia in humans|Myopia}}
{{Short description|Shortsightedness}}
File:Diceros bicornis.jpg, known for its poor eyesight]]
Some animals suffer from shortsightedness and have poor eyesight. In domestic animals, myopia, with or without astigmatism, occurs frequently.{{cite book|last1=Dukes|first1=Henry Hugh|last2=Hewitt|first2=Earl Albon|last3=McNutt|first3=George William|title=The Physiology of Domestic Animals|url=https://books.google.com/books?id=hEy4AAAAIAAJ|accessdate=31 October 2012|year=1935|publisher=Comstock publishing company, inc.}}
In rhinoceroses
Whereas the rhinoceros may suffer from less-than-adequate eyesight, it generally survives by concentrating with its superior hearing and sense of smell.{{cite book|last= Kingdon |first= Jonathan |title= East African Mammals: An Atlas of Evolution in Africa, Volume 3, Part B: Large Mammals|url=https://books.google.com/books?id=xdH_Gi92-fAC&dq=Myopia+in+Rhinos&pg=PA97|year=1988|publisher= University of Chicago Press|isbn=9780226437224|pages=96–97}} Some reports, however state that it can see better when focusing with one eye, particularly when walking, posturing, and combatting.{{cite book|last=Bates |first= William Horatio |title= The Cure of imperfect sight by treatment without glasses|url=https://archive.org/details/cureimperfectsi00bategoog|quote=Myopia in Elephants. |year=1920|publisher= Central Fixation Publishing Company|page=[https://archive.org/details/cureimperfectsi00bategoog/page/n124 100]}}
Research
Myopia, with or without astigmatism, is the most common eye condition in horses.
Several types of occlusion myopia have been recorded in tree shrews, macaques, cats and rats, deciphered from several animal-inducing myopia models. Preliminary laboratory investigations using retinoscopy of 240 dogs{{Cite journal|url=http://www.iovs.org/content/33/8/2459.full.pdf|title=Myopia and Refractive errors in Dogs|journal=Investigative Ophthalmology & Visual Science|volume=33| issue = 8|date=July 1992|accessdate=2 November 2012|publisher=Association for Research in Vision and Investigative Optholomology}} found myopic problems with varying degrees of refraction errors depending on the breed. In cases involving German Shepherds, Rottweilers and Miniature horses, the refraction errors were indicative of myopia. Nuclear sclerosis of the crystalline lens was noticed in older dogs.
Experiments into newborn macaque monkeys have revealed that surgically fusing the eyelid for one year results in eye deterioration as the eye has not had a chance to grow and develop.{{Cite journal
| last1 = Raviola | first1 = E.
| last2 = Wiesel | first2 = T. N.
| doi = 10.1056/NEJM198506203122505
| title = An Animal Model of Myopia
| journal = New England Journal of Medicine
| volume = 312
| issue = 25
| pages = 1609–1615
| year = 1985
| pmid = 4000200
| pmc =
}} Keeping monkeys in the dark for a similar period, however, does not lead to myopia. In 1996, Maurice and Mushin conducted tests on rabbits by raising their body temperatures and intraocular pressures (IOP) and noted that while younger rabbits were prone to developing myopia, older rabbits were not.{{cite book|last1=Rosenfield|first1=Mark|last2=Gilmartin|first2=Bernard|title=Myopia and Nearwork|url=https://books.google.com/books?id=mNT577S8uywC&pg=PA4|accessdate=31 October 2012|year=1998|publisher=Elsevier Health Sciences|isbn=978-0-7506-3784-8|page=4}} Some tests have revealed that myopia in some animals can be improved with eye drops containing zinc, by increasing the activity of superoxide dismutase (SOD).{{cite book|last=Schmid|first=Klaus|title=Myopia Manual|url=https://books.google.com/books?id=BX2r1F-GQREC&pg=PA96|accessdate=31 October 2012|date=28 June 2004|publisher=Pagefree Publishing|isbn=978-1-58961-271-6|page=96}}
The rhesus monkey's vision amplitude reduction is noticeable in its second decade of life; however the condition does not impede normal functioning. Older rhesus monkeys have more difficulty accommodating this reduction in vision amplitude, encountering difficulty in focusing on objects at close range, even objects on the ground within an arm's length.{{cite book|last=Rawlins|first=Richard G.|title= The Cayo Santiago Macaques: History, Behavior, and Biology|url=https://books.google.com/books?id=3fMCzTve890C&dq=Myopia+in+Animals&pg=PA244|year=1986|publisher=SUNY Press|isbn=9780887061356|pages=243–44}}