For many reasons, its almost certain that horses see things very differently to us. Horses’ eyes are one of the largest of vertebrates living on land.
- With a single eye horses can see around 228° compared with only around 155° in people.
- Binocular vision in horses is only around 60° in horses compared with 120° in people.
- Horses have poor visual acuity (ability to distinguish shape and detail) compared with other land-living mammals.
- Horses can perceive depth and three-dimensional structure but only in the binocular vision field which likely explains why they are able to jump well.
- The equine retina has no central fovea but instead has what is known as a “visual strip”. This is believed to allow horses to see a strip or band of the entire horizon, but much less above or below it.
- Head and neck position are important factors found to affect the visual abilities of horses.
- Horses can roll their eyes to keep things in focus.
- When a horses’ head is in an extreme hyperflexed position (i.e. significantly behind the vertical) the horse cannot roll its eye sufficiently to keep things in focus.
- Horses have very good low light/night vision.
- Horses appear to be able to see details better on overcast days compared with sunny days.
- Horses colour vision is dichromatic – this means they can only distinguish two of the three colours we can see (human vision = trichromatic; three colours).
- Horse vision appears to show laterality. Some studies suggest horses prefer using the left eye when observing people and for viewing objects that could have both positive and negative associations.
For more information on equine eye disease – Eye Disease in Horses & Ponies – Some Helpful Resources
