The pupil is the black area in the middle of the eye. It is controlled by the circular sphincter muscle. When the environment is dark, the pupil enlarges to let in more light; when the environment is bright, the pupil becomes smaller to let in less light. The shape of the pupil in horses is a horizontal oval.

The horse's wide range of monocular vision has two "blind spots," or areas where the animal cannot see: in front of the face, making a cone that comes to a point at about 90–120 cm (3–4 ft) in front of the horse, and right behind its head, which extends over the back and behind the tail when standing with the head facing straight forward.

The horse has a rectangular pupil shape which extends the area of visual perception. The size of the pupil determines the amount of light allowed into the back part of the eye. Pupils contract under bright light and enlarge in low light.

2023年5月15日 · Horses are generally thought to have good vision. Their large eyes and big pupils take in a lot of light, and the size of their retina allows a high number of cells to be involved in light capture and processing.

2016年6月18日 · Both eyes should be examined for pupil size and symmetry and for abnormalities such as synechia that may affect the PLR. One method to observe pupil symmetry in the horse is to use an indirect or direct ophthalmoscope directed at the center of the horse’s head from a distance of 6 to 8 feet.

2016年8月30日 · When you look into your horse’s eyes, the parts you’ll notice are the light-transmitting structures — the cornea, the aqueous humour (fluid) within the anterior chamber, the lens and the...

The foal or young horse has a round pupil, but it becomes more elongated horizontally as he grows older. By the time the horse is 5 or 6 the pupil is elliptical. The lens directs light rays onto the retina at the back of the eye.

The pupil contracts under bright light conditions and enlarges in low light. Just behind the pupil is the clear lens, which focuses an image on the back wall of the globe. The projection screen of the eye is called the retina.

2016年6月18日 · The horse eye is superior to the human in this regard because its pupil diameter has a greater dynamic range. 20 Another relatively rapid but more robust mechanism involves changing neural processing by the retinal bipolar and ganglion cells.

2019年12月9日 · Sometimes your horse’s pupil looks bluish-grey. What you’re seeing is the tapetum lucidum, a structure that reflects light back through the photoreceptor layer of the eye so that the horse has a high sensitivity to light, especially light reflecting off of the ground.