Here’s Why Cat Eyes Are So Unique

There’s almost nothing more instantly recognizable than a cat’s eye. The eyes’ unique colors and shapes make them stand out — and the unique way cat eyes work is actually even cooler.

To learn more about what makes cat eyes so special and how pet parents can best take care of their cats’ eyes, we talked to Dr. Julie Sanders, the director of operations at Heart + Paw. And the science behind their eyeballs proves that cats are magical creatures.

Though cats’ eyes are fairly similar to those of humans and other mammals, they have a special reflective structure at the back of the eye near the retina called the “tapetum lucidum.”

“This acts like a mirror, reflecting light back onto the retina,” Dr. Sanders told The Dodo. “This is part of what allows cats to see better than people in dim lighting. It also gives cats’ eyes that cool reflective glow.”

Cats also have a third eyelid that hides within the inner corner of the eye that partially covers the eye.

“The partial covering provided by the third eyelid protects the eye from trauma while allowing some vision,” Dr. Sanders said. “Most people don’t notice the third eyelid unless their pet is sick, injured or has a genetic abnormality (like prolapse of the tear gland in this lid).”

“No animal can truly see (with their eyes) in total darkness (an absence of light),” Dr. Sanders said. “Cats have anatomic differences that allow them to see in very low light that may seem like ‘dark’ to humans.”

The tapetum lucidum helps the light-sensing rods in the retina to be stimulated two times by a single light particle, Dr. Sanders explained. And cats’ rods are also differently proportioned and concentrated compared to the rods in human eyes.

“Rods, which provide black and white vision, are far more sensitive to light and require less photons for stimulation of vision,” Dr. Sanders continued. “Cats have more rods than people, enabling better low-light vision.”

Yes, cats can see some colors — but not all of them.

“They do have some cones, or sensors in the retina, that process color,” Dr. Sanders said. “Cats (like dogs) are red-green color blind,” but can see blues and yellows.

Cats’ eyes can be affected by many different medical issues and conditions. Here are some of the most common medical problems in cats that can affect the eyes.

Feline herpes is the most common disease that affects cats’ eyes, Dr. Sanders said.

“[Feline herpes] can cause discharge and ulcers,” she explained. “Nearly every cat experiences feline herpes virus in their lifetime, and symptoms can range from mild to severe. Ocular symptoms include protrusion (elevation) of the third eyelid, discharge, squinting and ulcers.”

Rough play, injury from foreign objects, and self-trauma caused by rubbing or scratching can cause cat eye injuries and issues like corneal ulcers, with symptoms including sensitivity to light, squinting, watery discharge, a dull appearance to the surface of the cornea, and proptosis of the eye (meaning the eye pops out of its socket).

“[Proptosis of the eye] is an emergency,” Dr. Sanders said. “If the optic nerve is still intact, it is possible to surgically save the proptosed eye. If it is not, your cat will need an enucleation to remove the eyeball to restore comfort.”

Luckily, only having one eye won’t affect your cat too much. Depth perception is really the only issue your cat may encounter after losing an eye.

Rotting teeth can cause abscesses to form in the jaw, which can cause swelling around the eye, and if not properly treated, “the pressure from this swelling could eventually cause blindness,” Dr. Sanders said.

Cancer in or near the face can also cause swelling, so take your cat to the vet ASAP to make sure the swelling is taken care of.

“Cats also can have retinal detachments from high blood pressure,” Dr. Sanders said. “Several chronic medical conditions such as kidney disease/failure and hyperthyroidism (both [of] which are common in older cats) can cause high blood pressure.”

If your cat has been diagnosed with one of these medical conditions, you should get her blood pressure checked at least every six months. “Yes, there is blood pressure medication for cats to treat hypertension!” Dr. Sanders added.

“Cats can sometimes develop cataracts, which is a change in the lense that makes it impenetrable to light,” Dr. Sanders said.

Cats, like humans, can actually undergo cataract removal surgery to have their vision restored. If your cat has been diagnosed with cataracts, talk to your vet about the pros and cons of having your cat undergo cataract-removal surgery.

Lenticular sclerosis is a natural increase in the lens density that occurs with age and is often confused with cataracts because the eye’s lens can appear cloudy.

“The two conditions can be difficult to differentiate. If you notice that your pet’s central eye seems hazy, get it checked out!” Dr. Sanders said. “Cataracts often occur with diabetes mellitus, which is treatable but best if diagnosed and treated early.”

If your cat is dealing with allergies or mites, she might lose some hair around her eyes. Set her up with a vet-approved pest preventative plan and talk to your vet about what you can do to treat her allergies.

The easiest way to make sure your cat’s eyes stay healthy is to simply pay attention.

“Healthy eyes don’t need any specific care,” Dr. Sanders told us. “The best thing a pet parent can do is pay attention to any changes in their pets’ eyes and [seek] medical attention if [they notice] any changes such as squinting; consistent protrusion of the third eyelid; discharge that is watery, mucusy or colored; cloudiness in appearance; swelling of the eye; or swelling around the eye. If your cat experiences any of these symptoms, it’s important to visit your veterinarian as soon as possible.”

And stay on top of annual or biannual vet appointments. An ocular health check and blood tests are always routine at these checkups, and your vet will be able to quickly detect symptoms of diseases that may affect your cat’s eye health.

“For first aid purposes, if you need to flush your cat’s eyes for any reason, use an over-the-counter eye wash or saline solution specifically labeled for the eyes,” Dr. Sanders said, and these washes and solutions can be found at most pharmacies. “Never put anything other than saline labeled ‘for the eye’ into a cat’s eye,” she continued.

Cats' eyes are just as incredible and unique as they are, and keeping a close eye (no pun intended!) on your cat’s ocular health will help you make sure that her vision stays crystal clear for years to come.