Equine vision

Homozygous cream dilutes, sometimes called double-dilutes, always have light blue eyes to match their pale, cream-colored coats.

[6] The eyes of horses with the Champagne gene are typically greenish shades: aqua at birth, darkening to hazel with maturity.

The lacrimal apparatus produces tears, providing nutrition and moisture to the eye, as well as helping to remove any debris that may have entered.

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.

[10] The horse uses its binocular vision by looking straight at an object, raising its head when it looks at a distant predator or focuses on an obstacle to jump.

To use binocular vision on a closer object near the ground, such as a snake or threat to its feet, the horse drops its nose and looks downward with its neck somewhat arched.

Such motion is usually first detected in their periphery, where they have poor visual acuity, and horses will usually act defensive and run if something suddenly moves into their peripheral field of vision.

This means they distinguish colors in two wavelength regions of visible light, compared to the three-color (trichromic vision) of most humans.

Therefore, most people paint their jump rails a different color from the footing or the surrounding landscape so that the horse may better judge the obstacle on the approach.

[17] The large eye of the horse improves achromatic tasks, particularly in dim conditions, which presumably assists in the detection of predators.

[18] Laboratory studies show horses are able to distinguish different shapes in low light, including levels mimicking dark, moonless nights in wooded areas.

"[19] However, horses are less able to adjust to sudden changes of light than are humans, such as when moving from a bright day into a dark barn.

It is also important in riding, as quickly moving from light to dark or vice versa will temporarily make it difficult for the animal to judge what is in front of it.

[21] However, this does not usually place them at a disadvantage, as accommodation is often used when focusing with high acuity on things up close, and horses rarely need to do so.