Glaucoma in Cats: Causes, Symptoms & Cure – Catmart
Health,  Illness & Injury

Glaucoma in Cats: Causes, Symptoms & Cure

Header image coutresy of Innovative Veterinary Care.

Feline glaucoma isn’t common, but it is serious. So what causes it, is it serious, and how do you fix it?

What is glaucoma, and how do cats get it? Glaucoma is a condition that affects the eyes and causes blindness. A build-up of aqueous fluid behind the lens of the eye causes the eye to swell, the eye/vision to become cloudy, and the optic nerve to be damaged. This build-up of fluid can either have a genetic cause (the eye produces too much fluid, or the ducts that drain the fluid can’t drain it quickly enough) or another health condition as the cause (where an infection, for example, causes swelling that stops the fluid draining). Glaucoma cannot be reversed but it can be managed. If it gets serious, surgery is the only option; eye removal surgery is the most common fix, although there is an expensive and difficult surgery that can retain the eye and restore vision.

The guide below covers everything you need to know about feline glaucoma. It starts by detailing what glaucoma is, and what it affects. It then describes what causes the condition in the first place, the symptoms of glaucoma you’re likely to see, how you can fix it (and whether it can even be fixed at all), and how to manage it long term.

What Is Glaucoma?

cat eye health
Glaucoma makes your cat’s eyes look cloudy like this.

Feline glaucoma is a condition that affects the eye. Glaucoma is when the watery fluid behind the lens, which is the frontmost part of the eye, is unable to drain correctly. This fluid is called an aqueous humor, and having it build up is why the eye turns a different color in glaucoma.

When this fluid builds up, it causes pressure in the eye, and on the optic nerve. This can result in nerve damage, which further reduces your cat’s vision. If left untreated glaucoma can result in either partial or total blindness. It can affect either one or both eyes.

There are two kinds of glaucoma: primary and secondary glaucoma. These are common medical terms frequently used to refer to health conditions. A secondary condition is one that occurs because of another health condition; in this case, glaucoma can occur because of uveitis, which is inflammation elsewhere in the eye. This is the most common cause. Primary glaucoma is glaucoma that occurs because the cat’s genetics/breed predispose it to the condition.

What Does Glaucoma Affect?

Glaucoma affects all parts of the eye. The fluid collects behind the lens, and light has to pass through it to get to the retina, which is where the light is turned into signals for the brain (i.e. sight). As such, glaucoma affects vision because the fluid physically blocks light. Glaucoma also makes your cat’s vision worse by putting pressure on the optic nerve.

What Causes Glaucoma in Cats?

There are two ways that glaucoma can be caused. It can either be caused directly by genetics, or it can be caused by inflammation of the eye stemming from a separate cause. Which kind of glaucoma your cat has determines how the condition will be treated.

Uveitis, Inflammation & Glaucoma

Uveitis is swelling that affects the uvea, which is a structure in the eye. The uvea is made up of three parts: the iris, which is the colored part of the eye; the ciliary body, which is what produces fluid in the eye; and the choroid, a thin layer of blood vessels and connective tissue that connects the sclera and the retina.

When pressure builds in the uvea, it stops fluid from draining in the eye. The drainage ducts that lead away from the eye become blocked with proteins and debris. Inflammation here is typically the result of bacterial or viral infection, like in conjunctivitis. Common causes include feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), feline infectious peritonitis (FIP) and toxoplasmosis.

There are therefore two ways that glaucoma can be related to inflammation. One is for the glaucoma to cause swelling, because the fluid that builds up causes pressure. The second is for inflammation elsewhere in the eye to cause glaucoma to occur.

Are Some Cats More Susceptible to Glaucoma?

Some cat breeds are susceptible to glaucoma. Burmese and Siamese cats are known to get it the most frequently. It’s also possible for an individual cat to be susceptible to glaucoma because of its genetics. There’s no telling if your cat is susceptible in this way.

If a cat is naturally susceptible to glaucoma, then it will develop bilateral glaucoma, i.e. in both eyes. If the glaucoma is secondary to something else, the glaucoma will most likely appear in only one eye. Secondary glaucoma in one eye is by far the most common form of the disease.

What Are The Symptoms of Glaucoma in Cats?

The symptoms of glaucoma are not as easy to spot as those of other conditions. The condition can progress very slowly, meaning that you hardly notice the progressive change.

Nevertheless, there are symptoms, and they are detailed below.

My Cat’s Eyes Look Cloudy

One of the first symptoms you’re likely to notice is that your cat’s eyes look cloudy. This is a result of the physical liquid building up behind the lens in your cat’s eye/s. This liquid is normally see-through, but when lots of it builds up, its slight opacity builds up too. This carries on to the point where the eyes appear cloudy and silvery.

My Cat’s Eyes Look Swollen

Glaucoma can cause, or is caused by, inflammation. You will therefore notice that one or both of your cat’s eyes are swollen. This swelling can affect either one or both eyes. If it affects just one eye, the glaucoma is likely secondary to uveitis. If it affects one eye, it could either be a serious infection or primary glaucoma, i.e. caused by genetics/breed.

This swelling is small at first but can get progressively larger, to the point where the eyeball is too large for its socket. You may not even notice this swelling at first, but you would be shocked at how swollen an eye affected by glaucoma can become. The eyeball or eyeballs can swell up to such a degree that your cat becomes blind, and the only safe way of dealing with them is by surgically removing them.

Redness Around The Eye

cat eyes
The initial symptoms of glaucoma look a little like conjunctivitis (redness, swelling and discharge).

There are also symptoms that go along with the inflammation. You may notice that your cat’s eye/s become red, which is a result of blood rushing to the area. This occurs when there is an infection: the body allows more blood to an area to let more white blood cells in, as white blood cells kill bacteria.

It’s also possible for your cat to poke and scratch at its eye. That’s because the condition is painful and the cat is trying to relieve it. This can cause grazes or scratches on or around the eye. These make the whole appearance of the eye even more red.

Vision Loss

Glaucoma will cause vision loss for your cat. This vision loss can be in one or both eyes, depending on whether both eyes are affected. It is caused by the means described above: the fluid caught under the lens physically blocks light from hitting the retina, meaning your cat can’t easily see through it. The pressure of the fluid building up, or of the inflammation that causes secondary glaucoma, will also put pressure on the optic nerve and stop it from working correctly.

In practise, this means your cat will struggle to see what it’s doing as it goes about its day. You may notice:

  • Your cat walking into things
  • Your cat missing jumps without the explanation of a soft tissue injury
  • Your cat getting surprised by things that it should have been able to see
  • Your cat is more tense, skittish and defensive than usual

Bear in mind that a cat’s vision isn’t good at the best of times. It’s thought that cat vision is roughly the equivalent of somebody very short-sighted. There are also other explanations for a cat’s failing vision. But if you notice these signs in conjunction with the others in this list, the likely cause is glaucoma.

Dilated Pupils

In a symptoms related to vision loss, you may also notice that your cat’s pupils are dilated. This dilation can range from slight to almost complete, i.e. where the pupil is open to almost the full width of the eye.

The reason for this is that your cat is struggling to see. When your cat opens its pupil further, it allows more light into its eye; more light can hit its retina. Allowing more light in means that your cat can see better in low light conditions. You will have noticed the same thing if you’ve ever seen your cat’s eyes in the dark. Your cat is trying to see despite its glaucoma being in the way.

Is Glaucoma in Cats Painful?

Glaucoma can be a very painful condition for your cat.

When the condition first begins, it will hardly even inconvenience your pet. The swelling and vision loss will be so slight that neither your cat nor you will notice. But as it gets worse, and the swelling gets bigger, glaucoma will start to hurt your cat. The eye has nerves in it, which makes sense: sight is a delicate sense and the eyes have to be protected from things getting in them like dust and hairs. This means that your cat will feel that there is a swelling in its eye, and swellings hurt.

In practise, this means you may notice signs that your cat is in pain. You may notice:

  • Increased defensiveness
  • Lethargy, i.e. not having the energy to do things
  • Lack of appetite
  • Decreased interest in playing with toys
  • Pawing at the eye and the areas around it
  • Staying out of site and trying to get away from people/other cats

These symptoms will become more apparent as the condition gets worse.

Can Glaucoma Kill a Cat?

Glaucoma can kill a cat either on its own, or as part of a wider problem.

Since glaucoma is typically secondary to an infection, it stands to reason that if that infection is left untreated, it can go on to kill your cat. That happens when the infection reaches your cat’s blood stream. From there, the bacteria/virus spread around the body and infect the organs. When the organs shut down, the cat dies. This is known as sepsis/septicemia. This is not strictly caused by the glaucoma—it’s caused by the infection that caused the glaucoma in the first place—but this does mean when your cat has glaucoma, it’s possible that it can die from complications of the issues it’s experiencing.

It’s also possible for primary glaucoma to kill a cat. The swelling can continue until the eyeball ruptures, at which point bacteria or viruses can get into the eye. This, again, could kill your cat through sepsis/septicemia.

There are also other roundabout ways that glaucoma can seriously hurt your cat. Your cat could sustain injuries from a fall, for example. Or it could be more easily injured by a car, another cat, or another pet.

Can You Fix Glaucoma in Cats?

The first thing you should do if you notice that your cat is ill in any way is to take it to the vet. You may think both that you can diagnose and treat cat health conditions at home, and sometimes, you can. However there are important things to remember especially when the condition is serious:

  • It is easy to misdiagnose the problem. You may think that your cat has incurable primary glaucoma, when the issue is actually uveitis. You can stop the swelling of uveitis when it’s caused by something like toxoplasmosis.
  • Vets have access to the best medicines and other cures. One of the fixes for glaucoma, for example, is surgery. You obviously can’t perform surgery at home.

Vets can also diagnose glaucoma with a high degree of accuracy. First, your vet will look at your cat’s medical history, and perform a thorough check of your cat’s eyes. To confirm their diagnosis, they will use a tool called a tonometer. This blows a puff of air at your cat’s eye, by which it measures intraocular pressure (the pressure inside the eye). If it is higher than normal, and the symptoms above are present, then they will diagnose glaucoma.

Can Glaucoma Be Cured? (& Cat Glaucoma Eye Removal)

Primary glaucoma cannot be reversed. There is no way of quickly draining the eye with a needle, as can be done with things like boils/abscesses. There are no tablets that can ease the swelling. Secondary glaucoma can be managed and its symptoms made less severe, but if it is allowed to continue until the eyeball is heavily swollen, then again there is no simple fix.

One way in which glaucoma is managed is through the application of eye drops. There are several kinds of eye drops which the vet might prescribe. These work in different ways:

  • Dorzolamide 2% drops. According to patient.info, “Dorzolamide works by blocking the action of an enzyme called carbonic anhydrase. Blocking this enzyme reduces the amount of fluid that you make in the front part of your eye (called aqueous humour), and this helps to lower the pressure within your eye.” These drops work the same way when they’re given to cats.
  • Timolol 2.5% drops. Patient.info state that “Timolol eye drops work by lowering the pressure in the eye. It is thought they do this by reducing the amount of fluid that the eye makes that fills the front part of the eye (called aqueous humour). By reducing the amount of fluid produced, it reduces the pressure within the eye.” They may also help drain fluid from the eye.
  • Steroid drops. These can reduce the level of inflammation in the eye. So, if the glaucoma is secondary to inflammation, these can reduce the effects of the glaucoma too.

Follow your vet’s guidance with regard to how often these drops are administered. Twice or three times a day is a common recommendation.

The current method of treatment for severe glaucoma is surgery on the eye. There are two different kinds of surgery that can be performed. One allows the eye to drain (trabeculectomy), while the other is removal of the eye (enucleation). Removal of the eye is the sugery commonly performed when the eye gets too big to fit correctly in its socket. The surgery involves making small incisions around the eye to allow it to come out easily, removing it with a scalpel, and sealing the wound afterwards.

Trabulectomies are even more complex surgeries. These involve using a special laser to destroy the fluid-producing tissues responsible for primary glaucoma. The surgeon will also remove the lens and replace it with an artificial one. Eye removal is a common surgery performed by vets, but trabulectomies are not. They are only performed at specialist centers.

Cat Glaucoma Treatment Cost

The cost of treatment depends on what kind of treatment your cat receives. The cost is typically somewhere between $1000-$2000.

Trabeculectomies aren’t offered everywhere, and are more difficult surgeries to perform than removals. You may therefore be charged more for a surgery to save your cat’s eye/s than a simpler surgery to remove them. Talk to your vet about your options, and the cost of each surgery.

Natural Treatment for Glaucoma in Cats

There is no natural cure for glaucoma, just as there is no medical cure. You shouldn’t use natural treatments like supplements or ‘natural’ eye drops instead of seeking veterinary treatment for your cat. If you use the treatments alongside proper medical treatment, that’s not a problem, and they may work to alleviate some of the symptoms of glaucoma. But using them instead of getting your cat surgery, or managing its pain and eye pressure another way, is a bad idea.

Can Cats Live with Glaucoma?

As glaucoma is not something that can be reversed, your cat must learn to live with the condition. This is possible, and your cat can live a long and happy life regardless.

Managing The Symptoms of Glaucoma in Cats

Glaucoma will cause your cat pain, and you have to manage that pain for your cat to live a full life. The vet will prescribe painkillers you can administer to your cat. These are typically pills that you add to your cat’s food. Both steroidal and non-steroidal painkillers may be used.

Sometimes, managing the pain of glaucoma is the only course of action that the vet may recommend. If the eye is not severely inflammed, they may not want to put the cat through surgery, especially if it has health conditions that mean it may not survive anesthetic.

Caring For a Cat With Glaucoma

Whether your cat has lost its vision because of the glaucoma, or it has had its eye/s removed, you need to accommodate for that fact. You must make your house easy to navigate for your cat, or it will struggle to adapt to losing its sight. The good news is that cats rely on their senses of smell and hearing more than we do. A cat’s eyesight is akin to a person with very severe short sightedness (and that’s without glaucoma). As such, small adjustments can go a long way. Ways to make your cat more comfortable when it loses its sight include:

  • As much as possible, don’t move things around. Your cat has a mental map of where things are in the house. If you were to move its food bowl somewhere else, it may struggle to find it. The only instance in which you should consider moving your cat’s things is if they’re difficult to access (e.g. it has to jump to reach them).
  • Keep your house clutter free. Your cat may hear and smell some things, but it won’t know if there are obstacles in its way. It will find out by bumping into them. Getting rid of as much clutter as possible stops your cat experiencing these nasty surprises.
  • Use smell to make your cat feel comfortable. Your cat will feel vulnerable because it can’t see. Cats use pheromones to mark their territories. If you haven’t already, give your cat toys, beds and soft furnishings that will hold onto its scent and give it places that it literally feels at home.
  • Remember your cat can’t see when you approach it. It’s easy to forget that your cat can’t see you, at least at first. When you approach your cat, talk to it in a low tone, and offer it your hand for it to sniff. And don’t make light of its condition by sneaking up on it, as this will just make it uncomfortable and unhappy.
  • Forgive your cat if it’s defensive. Your cat may hiss at you, scratch you, try to get away from you or not want you to pet it. If that’s the case, you have to respect that. Your cat feels vulnerable and may take time to feel safe around you again.

Another piece of good news, in a sense, is that your cat has already been dealing with its sight loss for a while. Glaucoma causes sight loss long before it necessitates eye surgery. As such, your cat may already have gotten over the initial vulnerability it feels when it loses its sight.

Other than this, if you’re ever concerned about your cat’s health for this or another reason, take it to the vet as soon as possible.

Hi! My name is Jamie Fallon. I run Catmart, an online cat health and cat behavior resource. If I'm not sat in front of my PC—and I usually am—then I'm either spending time with my cats or my other half... Whoever jumps on me or asks me for food first!

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