Does anyone know if horses can be short or long sighted?

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Rouletterose

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as above really just wondering if your horses eyesight is ok, can they get short or long sighted in one eye or both the same as we can? and when vets check their eyesight is there a special eye test for this? just want to know as they just have to put up with it I suppose as they can't wear glasses can they?
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I'm pretty sure my old loan horse was short sighted. Her eyes were stucturally normal (all you can test) and she could definitely see, but she wasn't quite right, vision wise.
 
Horses have a limited focusing ability. The optical power of the human lens can change by as much as 10 diopters, while dogs have 1-2 diopters, rabbits 0, and horses are about 2 diopters.

What is different about the horse retina is that it is naturally focused on distant objects and can make limited accommodations for near objects. So horses are naturally presbyopic if you want a human analogy.

Another interesting finding is that the main axis of the horse eye has a very high concentration of ganglia, which may mean that images that fall outside this area may be difficult to perceive - this may explain why horses are suddenly startled by objects that seemed to be in their field of vision all along.

Main study on retinal focusing:
Sivak J.G., and Allen D.B., "An evaluation of the ramp retina of the horse eye" Vision Research, 15 (1975) 1353-56
 
Booboos, that is interesting. I have done some reading about the field of vision but didn't know the other. My old horse did have a contact lens......it wasn't to improve his eyesight though but to protect it whilst healing from a scratch. Was somewhat bigger than my contacts!
 
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Horses have a limited focusing ability. The optical power of the human lens can change by as much as 10 diopters, while dogs have 1-2 diopters, rabbits 0, and horses are about 2 diopters.

What is different about the horse retina is that it is naturally focused on distant objects and can make limited accommodations for near objects. So horses are naturally presbyopic if you want a human analogy.

Another interesting finding is that the main axis of the horse eye has a very high concentration of ganglia, which may mean that images that fall outside this area may be difficult to perceive - this may explain why horses are suddenly startled by objects that seemed to be in their field of vision all along.

Main study on retinal focusing:
Sivak J.G., and Allen D.B., "An evaluation of the ramp retina of the horse eye" Vision Research, 15 (1975) 1353-56

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Mmmmm...very interesting stuff explains a lot I think about one of mine also her eyes seem to be set a little more round to the side than some, so really we can never be 100% sure about how good our horses eyes are?
 
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I'd say that it is a pretty likely explanation for some horses being more spooky than others.

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That's what I thought too
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For anyone interested in more info on the horse's eye and vision try:

Budiansky S., "The Nature of Horses", Phoenix, 1998

It's a book on the science of evolution, biology and ethology of horses but written by a science journalist so he distills what might otherwise be rather dry science topics into a more regular-reader friendly version and has a good bibliography for anyone who wants to read more. You can pick it up on Amazon for under six pounds.
 
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