BEHAVIOR & TRAINING

Why Do Cats Eyes Glow: Caring for Your Cat’s Amazing Eyes

cat's eyes in the darkness
Stella Noble
Written by Stella Noble

If you have ever seen a pair of disembodied eyes glowing in the dark and moving slowly towards you, you know how eerie it can be, even if you are aware that it is just your feline pet approaching you. Experiencing that even just once can make you wonder why do cats eyes glow.

The eyes of cats are extraordinary visual organs. They are built differently compared to human eyes because they serve a different purpose, which is to give cats better nocturnal vision. Knowing the anatomy of your pet’s eyes and why they glow at night can help you take better care of your cat’s eye health.

In this article, we’ll first talk about the anatomy of feline eyes so we can gain a deeper understanding of why do cats eyes glow in the dark. We’ll then talk about common feline vision problems that may steal the light away from your cat’s eyes. We’ll also talk about symptoms of feline eye problems you should watch out for. Lastly, we’ll give you some tips on how to check if your cat has vision problems so you can react accordingly to preserve that light.

Anatomy of Feline Eyes – How They See and Glow in The Dark

cat's eyes anatomy

Overall, the eyes of cats have the same basic component as human eyes. And they function in the same way, too.

Cats have a cornea which is transparent and forms the outer covering of your pet’s eyeball. Then, your pet also has a pupil which is found in the center of the eye and is responsible for permitting light from the environment to enter the eye.

Your cat also has an iris which is a pigmented membrane. It surrounds the pupil, and this is the part of the eye that either contracts or expands, depending on whether it is bright or dark.

The eye lens is also transparent. Its shape adjusts in order to properly focus on the image that your cat is seeing. Your cat also has a retina which converts the received light impulses to visual information. The retina then sends the visual information to the brain through the optic nerve. And then there’s the tapetum lucidum.

Cats are, in general, nocturnal creatures. And to help them see better at night, their eyes are anatomically different than ours, though similar. At the back of your pet’s eyeballs, there’s a special reflective layer which is called the tapetum lucidum. Humans don’t have this reflective layer, but other nocturnal creatures like owls do.

The tapetum lucidum is an iridescent membrane. It reflects light back to the retina and is capable of detecting even slight rays of light.

When your cat is prowling in the dark at night, your pet’s eyes need to trap as much light as possible so that your pet can see where she is going.

The tapetum lucidum in your cat’s eyes basically serves as a vision booster that helps your cat see better at night. This extra layer in cats eyes is still part of their genetic heritage from their wild ancestors who were excellent nocturnal hunters.

When there’s even a slight ray of light, it will reflect off objects and enter your cat’s cornea. The light then crosses your cat’s pupil, and then on through the iris. The iris then decreases or increases in size depending on how much light is passing through.

In the dark, your cat’s pupils will be open extra wide in order to let in as much light as possible. But when it is bright like during daytime, your pet’s pupils won’t dilate as much because there’s sufficient light for your cat to see what’s happening around her.

After the light passes through the pupil and the iris, it will then course through the eye’s lens. The lens is the structure that is responsible for image focusing. After going through the lens, the light will then travel on to the retina. Then the retina sends the information back to the brain so that your pet can process what she is seeing.

This is the part where the tapetum lucidum plays a key role. Behind your cat’s retina, you’ll find the tapetum lucidum. Light gets reflected from the tapetum lucidum back to the retina. Experts say that this reflection process is like a second chance for cats to absorb the light and see the image again.

What’s even more amazing about the tapetum lucidum is that it can multiply whatever little light there is up to fifty times. As the tapetum lucidum magnifies the light and reflects it back to your pet’s retina, it makes your cat’s eyes glow.

Despite this amazing extra layer in the eyes, your feline pet still cannot see when there is total darkness. The tapetum lucidum is only able to reflect light when there is actually some light available. In total darkness, the tapetum lucidum cannot reflect anything, and your cat will be almost blind.

Only almost blind but not totally blind, at least not visually. That’s because cats rely on their other heightened senses to figure out what’s going on around them. For instance, cats have extra sensitive sensory receptors in their whiskers that can even detect changes in the direction of air currents.

So, even if it is totally dark, your pet still won’t feel blind or lost. She’ll still be able to navigate through her surroundings by using all her acutely sensitive senses. And that’s another reason why cats are simply so awesome.

Aside from the tapetum lucidum which makes feline eyes different from that of humans, cats also have a “haw,” which actually serves as a third eyelid. This thin membrane is located at the eye’s inner corner. You can find it in between your pet’s eyeball and lower eyelid.

The haw serves to protect your cat’s eyeball from being scratched by growing hair. It also keeps your pet’s eyeball moist. And if in case your pet gets involved in a fight with another cat or another animal, the haw serves as a shield to prevent eye injuries.

Feline vision problems may involve any of the basic components found in their eyes. When feline vision problems are diagnosed and treated early, you can prevent your cat from going blind. This is why it is important to always have your pet’s eyes checked.

See Also: Why Do Cats Stare at Nothing

Common Feline Vision Problems

Because cats have unique vision features, their eyes are quite sensitive and are vulnerable to injury. There’s a wide variety of eye disorders and diseases that can impair your pet’s vision or cause your pet to become partially or even completely blind.

In fact, poor eyesight and blindness are common in middle-aged or elderly cats. When a cat’s eye disease is left untreated, it can progress to blindness as the cat ages. There are actually several behavioral signs that indicate your pet is having vision problems. When you notice those signs, you should take your pet to the vet right away.

#1: Cataracts and Glaucoma

cat with cataract

Feline eye disorders include cataracts and glaucoma. Cataracts occur when the lens becomes clouded. This happens gradually, but when you notice it, you should have your pet checked right away. When your pet has cataracts, the cloudy covering actually prevents light from entering your pet’s eye. This means your cat can’t see anymore.

Glaucoma, on the other hand, occurs when the eyeball hardens due to excessive fluid pressure within it.

#2: Progressive Retinal Atrophy

Other feline eye problems include progressive retinal atrophy wherein the retina deteriorates and is no longer able to function properly.

#3: Eye Infections

cat with eye infections

Other cat eye problems may be caused by bacterial, fungal, or viral infections. For example, a cat may develop an eye problem because of the feline leukemia virus (FLV), the feline immunodeficiency virus (FIV), the feline herpes virus (FHV), and the feline infectious peritonitis virus (FIP).

When your cat is infected by any of these viruses, it can cause various health problems and not just impaired eyesight. Aside from these viruses, your cat may also be infected by a parasitic organism called toxoplasma or cryptococcus which is a fungus.

#4: Conjunctivitis

Among the various feline eye diseases, conjunctivitis is one of the most commonly diagnosed. This can happen when your cat has an upper respiratory disease due to a viral or bacterial infection. When your cat has conjunctivitis, the outer surface of the eyeball and the membrane lining the eyelid’s inner surface are inflamed.

Aside from being swollen, your cat’s eyes will also become runny if your pet has conjunctivitis. This eye disease is actually highly contagious, so you need to have your pet treated right away so that the disease won’t spread, especially if you have other cats in your home.

#5: Uveitis

cat with uveitis

While conjunctivitis is one of the most common, the one that’s considered as one of the most severe eye problems in cats is called uveitis. This condition is usually caused by either an FIP, FIV, or FLV infection. When your pet has uveitis, her uvea or the middle area of her eye becomes inflamed.

Uveitis can actually cause feline blindness. When you see your pet’s eyes becoming noticeably enlarged, or when there’s an inflammation in her eyeball, or if your cat keeps squinting, it is highly likely that your pet has uveitis.

#6: Retinal Detachment

Retinal detachment is the second most common eye disorder that can cause blindness in cats. This happens when your pet’s retina becomes detached from the tissue underlying it.

This may be caused by a leakage of fluid between the retina and the underlying tissue. Retinal detachment is common in cats with high blood pressure, kidney disease, and an overly active thyroid gland.

#7: Injuries

Other factors that can cause blindness in cats include corneal lacerations or when the outer surface of your pet’s eye becomes lacerated or cut.

Symptoms That Tell You Your Cat Is Having Eye Problems

clumsy cat

When your cat has vision problems, she won’t be her usual graceful and confident self. You’ll find some warning signs of eye trouble in the way your cat behaves. In many cases, feline blindness can be prevented through prompt diagnosis and treatment.

Here are some symptoms you should watch out for.

  • Easily startled. If your cat gets easily startled or shocked, it may be because she’s not seeing what’s happening around her. You’ll notice it in the way your cat doesn’t seem to know where you are, even if you’re in the same room.

  • Always squinting. This isn’t normal behavior for cats. When your pet seems to be squinting all the time, either in both eyes or in just one of her eyes, this could be a sign that she’s having trouble seeing. Your pet could be squinting because she thinks it might help her see better.

  • Hesitation. Cats are usually extremely confident about the fact that they can navigate their way through most obstacles. If your pet shows hesitation as she walks around the house, it could be because she’s unsure of what’s in front of her. This could be another sign that she’s having eye problems.

  • Clumsiness. Cats don’t usually bump into things, whether it is a piece of furniture or the door. A healthy cat can gracefully skirt around whatever’s lying on her path. If your pet keeps on bumping into things, it is a sure sign that she can’t see clearly.

  • Staying close to the ground. If your cat is always crouching down, it could be that she’s feeling some apprehension about moving around. She may be crouching down so she can stay close to the ground because she’s afraid she’ll fall, even if she’s already on the floor. This could be because your pet’s vision is already blurry or maybe she can’t see anymore, and she doesn’t even know that she’s on the floor already.

  • Disoriented and extremely vocal. Vocalizing might be a hobby for your cat, but if it is accompanied by disorientation, your pet may be telling you that she’s confused and frustrated about it. When your pet is losing her vision, disorientation is a natural consequence. She may be yowling because she’s asking for help. She could be feeling lost and asking for someone to help her find her way back.

  • Temperament changes. As your cat’s vision slowly deteriorates, it will be accompanied by temperament changes. Your pet may become nervous, anxious, or scared. These behavioral changes are usually signs that something’s wrong with your pet.

  • Changes in your pet’s eyes. Cloudy, foggy, or discolored eyes are bad news, especially if it is accompanied by goo around the corners, watering, or unusual eye discharge. Unequal pupil sizes, a protruding third eyelid, or tearing in the corners of your pet’s eye are sure signs of eye problems.

How to Check Your Cat’s Eye Health

checking cat's eyes

You don’t have to wait for the symptoms of feline vision problems to manifest themselves. You can check your cat’s eye health regularly. Here are some tips on how you can do it yourself.

  • Changes in appearance. Check your pet’s eyes to see if anything changed in their appearance. Look for cloudiness, swelling or inflammation, increased redness, altered reflections, or eye enlargement. Any of these signs warrant a visit to the vet.

  • Slowly place your hand in front of your pet’s eyes. You should do this while your cat is awake. Do it calmly and slowly so that your pet doesn’t feel threatened. You’re looking for reactions. Your pet should blink or turn her head away as you slowly move your hand toward her. If she does not react at all, it is likely that she does not even see your hand approach.

  • Shine a light into your pet’s eye. You can use a penlight or a flashlight. Watch your pet’s reaction and see if she will turn her head, squint her eyes, or blink. When your pet doesn’t respond at all, your pet may already be losing her vision. If your pet’s pupils are healthy, they will constrict when exposed to bright light.

  • Drop a cotton ball in front of your pet. Place your hand directly above your pet’s head. Drop the cotton ball slightly in front of her face. You can also use a small feather or a sheet of paper, anything that doesn’t fall too quickly. Your pet should be watching the object as it falls to the ground. If she’s not even looking at the object or she’s not aware that something is dropping in front of her, her vision may already be impaired.

  • Place your cat on an elevated surface. Place your pet about a foot or a foot and a half above the floor. Observe her as she tries to find her way down. For cats with normal vision, jumping down from a height of two feet is nothing. However, if your cat has poor vision, she won’t just jump. She will feel her way with her feet before climbing down. She’ll also show hesitation where in the past she would just jump down as if she has no fear of falling from great heights.

See Also: How High Can a Cat Fall

Wrap Up

cat's eyes in the dark

If your cat’s eyesight is failing, she will rely on your help almost all of the time. She will need a lot of support and caring. If you observe any signs that your pet’s vision is deteriorating, you should take her to your vet without delay.

If you have any other tips on how to check a cat’s eye health, do share them with us. Please feel free to leave other comments and suggestions as well. You read this article because you’d like to understand your cat better, and in that case, we’re certain you will like our next article on why do cats like milk as well.

About the author
Stella Noble
Stella Noble

Stella Noble lives in Warren, Michigan with her family and three cats. She is a Certified Cat Trainer and a member of the International Association of Animal Behavior Consultants.

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