Anyone with a feline friend sharing their home with them probably knows how it feels to wake up to the sound of tiny feet scampering across the floor in a dash, or an object hitting the floor after being knocked from a high place. Cats are known for their night prowling abilities, but what makes them so good at navigating the world after dark? And, how does their overall eyesight compare to their nighttime vision or other animals?
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How cats see
Cats have a pretty wide field of peripheral vision, which measures about 200 degrees, just 20 degrees more than the field of vision of a human being. Since they are hunters by design, this increased visibility gives them an advantage over prey, making fast-moving animals like rodents and birds easy to spot for a feline. Two photoreceptors aid a cat's vision: the cone cells in a cat's eye make spotting movement easy, and the rod cells make visibility in low light situations possible. This combination is part of what makes cats the apex predators that they are.
Cats also have a third eyelid, which protects the eyes from harm and allows them to function properly. This is called the nictitating membrane and is found in the inner corner of the eyes near the nose. The membrane helps cats stay safe from scratches, and allows them to easily maneuver through tall grass or thick bushes.
Is their eyesight good?
While the answer to this question will depend on the health and age of a specific cat, generally, cats do have pretty good eyesight in some situations. When viewing things up close, their abilities surpass those of a dog's but aren't quite as finely tuned as the near-sight of a person. They aren't very adept at seeing things far away, as their eyes have naturally adapted to assist them with pouncing on things a short distance away. Cats are also color blind, and their color comprehension abilities are even worse than that of a dog's — blues and greens are reportedly easier for them to see than reds and pinks.
An edge cats do have on dogs and people, however, is their ability to see in very low light situations, and even in complete darkness. Much of a cat's eyesight has evolved to fit their hunting abilities and their sleep cycles, so because felines naturally stir around dawn and dusk, a cat's eyes have adapted to help them see during these hours. A cat's night vision can be attributed to the shape of the cornea, and tapetum, which rests behind the retina. This part magnifies light and is the reason cats' eyes often look reflective or glowing in the dark. The tapetum also makes cats sensitive to bright light.
Common eye issues in cats
Eye issues can arise in cats at any time of their lives, but most experience issues in their later, senior years. Cataracts and glaucoma are among the most common eye diseases found in cats and are often attributed to old age, progressing slowly over time. Sometimes, however, viral or bacterial infections can lead to eyesight impairment in cats and include feline immunodeficiency virus (FIV,) feline leukemia, toxoplasma and feline herpesvirus. Additionally, conjunctivitis, which is the most commonly diagnosed disorder affecting a cat's eyes, is highly contagious and can usually be spotted when noticing runny eyes in a cat.
More serious disorders that can lead to blindness in cats is when the retina becomes detached, which can be symptomatic of kidney disease, high blood pressure, or an overactive thyroid. Preventative care is the best way to spot early signs of eye diseases or dysfunction, and treatment is possible for many eye-related issues.
Cats have excellent eyesight in low light situations, far better than humans or dogs do. They can see pretty well up close but aren't highly adept at fine-tuning things very far away. Because their eyes are such an important part of a feline's survival, their ability to see at dawn and dusk has evolved over time to allow them to skillfully stalk and hunt prey, and a third eyelid keeps the eyes safer from potential harm, like scratches and debris. Eye diseases and disorders can lead to significant eyesight impairment or even blindness and should be discussed with a veterinarian to find a possible course of treatment.