Does Your Horse Need Glasses?
A study in the UK tested the eyesight of 333 horses. It noted that only 68% of horses have perfect vision in both eyes. Horses with impaired vision were either farsighted (hyperopic) or nearsighted (myopic). A breed difference was also noted. Warmbloods and Shires were more likely to be farsighted and Thoroughbred crosses nearsighted.
(Source: Vet Ophthalmol. 2014 Jul;17 A retinoscopic survey of 333 horses and ponies in the UK. Bracun A, Ellis AD, Hall C.)