Cat With Red Eyes -Why Are My Cat’s Eyes Red?

closeup of a cat's eye green color

Do you have a cat with red eyes? If you have, you have probably also wondered why they are red and if you need to be concerned.

Red eyes in cats can be caused by several conditions including conjunctivitis, uveitis, glaucoma, and corneal ulcers. These conditions can be caused by injury, infection, allergies, underlying eye conditions, and systemic diseases. Cats with red eyes should see a veterinarian to protect their vision. 

Understanding the causes of red eyes in cats and their associated symptoms can help you determine whether your pet needs immediate medical attention.

In this blog post, we will explore the anatomy of a cat’s eye, the different reasons for redness, the associated symptoms, and how to prevent and treat this condition.

Importance Of Cat’s Eyes

Like all creatures that rely on their sense of vision, a cat’s eyes are incredibly important to their overall health and wellbeing. Not only do they play a vital role in a cat’s ability to see and navigate their environment, but they also provide valuable insight into their emotional state and overall health.

A cat’s eyes have several unique features, including a wide range of motion, incredible low-light vision, and a reflective layer called the tapetum lucidum that enhances their ability to see in low-light conditions. These features make cats incredibly skilled hunters, capable of seeing prey in near-total darkness.

Additionally, a cat’s eyes can reveal a lot about their emotional state. For example, if a cat’s pupils are dilated, they may be frightened or excited. Alternatively, if their pupils are constricted, they may be feeling content or relaxed. These subtle cues can help you understand your cat’s mood and respond accordingly.

Overall, a cat’s eyes are a critical component of their health and well-being, and it’s essential to keep them healthy and free from any abnormalities or conditions that could affect their vision or overall health.

When To Be Concerned About A Cat’s Red Eyes

Some cases, a cat with red eyes may be due to temporary reactions, such as irritation from environmental factors such as smoke or pollen in the air. However, persistent redness or other symptoms can indicate a more serious issue.

For example, redness in a cat’s eyes may be a symptom of a viral or bacterial infection, such as conjunctivitis or uveitis, which can lead to discomfort, pain, and potential vision loss if left untreated.

Additionally, red eyes can be a sign of glaucoma, a condition in which the pressure in the eye becomes too high, causing damage to the optic nerve and potentially leading to blindness.

Red eyes in cats can also be a sign of a corneal ulcer.

These are all serious medical conditions that require prompt veterinary attention. If your cat has red eyes, it’s important to watch for other symptoms and to seek appropriate veterinary are when needed.

Causes Of Red Eyes In Cats

As mentioned above, red eyes in cats can be caused by a variety of factors, including environmental triggers and medical conditions.

Environmental causes include smoke, pollen, and other allergens that your cat may come into contact with. These irritants can lead to temporary redness or swelling of the eyes that should clear up once the allergen is removed.

Medical conditions that can cause red eyes in cats include conjunctivitis, uveitis, glaucoma, corneal ulcers, and cataracts. Each of these conditions have different causes and require specific treatments. Let’s look at these a little closer.

Conjunctivitis In Cats

Conjunctivitis in cats (pink eye), is a condition in which the conjunctiva, the thin and transparent tissue that covers the white part of the eye and the inner eyelid surface, becomes inflamed.

Conjunctivitis can affect one or both eyes and can be caused by a variety of factors, including bacterial or viral infections, allergies, and injuries.

Causes Of Conjunctivitis

Bacterial conjunctivitis in cats is usually caused by bacteria such as Mycoplasma or Chlamydia, while viral conjunctivitis is typically caused by feline herpesvirus or feline calicivirus.

In some cases, conjunctivitis in cats may be caused by environmental factors, such as exposure to smoke, dust, or other irritants, or allergies to pollen or other substances. While these causes are usually temporary, long-term exposure may cause ongoing symptoms.

Conjunctivitis due to these causes usually occurs in both eyes at the same time (or starts in one and quickly spreads to the other). If only one eye is affected, then the cause is more likely to be something like an injury, foreign object in the eye, or a blocked tear duct.

Symptoms Of Conjunctivitis In Cats

Common symptoms of conjunctivitis in cats include redness, swelling, discharge, squinting, and rubbing or scratching of the eyes. The cat will also likely experience discomfort or pain, which can cause them to avoid bright light or close their eyes more often than usual.

In severe cases, conjunctivitis can lead to corneal ulcers, which can be painful and potentially cause permanent vision loss if left untreated.

Treatment Of Conjunctivitis In Cats

Many cases of conjunctivitis in cats is self-limiting (goes away on its own). But if symptoms don’t subside in a day or two, if it worsens or if the cat is in obvious distress, then it should be taken to a veterinarian for treatment.

Treatment for conjunctivitis in cats typically involves identifying and treating the underlying cause of the inflammation. Depending on the cause, your veterinarian may prescribe antibiotics, antiviral medications, or anti-inflammatory medications which are usually administered as drops to the eyes.

In some cases, your cat may need to wear an Elizabethan collar to prevent them from scratching or rubbing their eyes, which can further irritate the condition.

Cats with herpesvirus may have recurring episodes of conjunctivitis throughout their lives, because, once infected, the infected cat will carry the virus for the rest of its life.

cat with red eyes - closeup image of a orange eyes in a grey cat face

Uveitis In Cats

Uveitis in cats is a condition that involves inflammation of the uveal tract, which is the middle layer of the eye that contains the iris, ciliary body, and choroid.

The iris is the colored part of the eye, while the ciliary body produces aqueous humor (the fluid that fills the front of the eye) and controls its pressure. The choroid is a layer of tissue between the retina and sclera (the white part of the eye) that contains many blood vessels and helps to nourish structures within the eye.

Causes Of Uveitis In Cats

Uveitis in cats can be caused by injury or damage to the eye itself, such trauma, tears or holes in the cornea (such as penetrating corneal ulcers), or tumors in the eye.

It can also be cause by variety of systemic diseases, such as feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV), by fungal infections like Cryptococcosis, or by parasitic infections such as Toxoplasmosis

Uveitis in cats can also be caused by immune-mediated, meaning that the cat’s own immune system begins attacking its eye tissues, leading to inflammation. There is often a trigger associated with this, such a exposure to a drug, vaccine, or a toxin.

Uveitis can even by caused by general systemic problems such as a systemic infection, high blood pressure, or high cholesterol.

Since there are so many potential causes of uveitis in cats and the risk of permanent damage to the eye is high, cats suspected of having uveitis should be seen by a veterinarian as early as possible.

Symptoms Of Uveitis In Cats

Onset of uveitis in cats may be rapid, or they may come on gradually. Although uveitis is quite painful, cats are masters at hiding pain so you might not notice symptoms until the condition is well advanced.

Common symptoms of uveitis in cats include:

  • Red eye is most commonly the first symptom noticed
  • May affect one or both eyes
  • Sensitivity to light – squinting, excessive blinking
  • Watery eye or eyes
  • Eye discharge
  • Iris may change color or appear cloudy
  • Eye may bulge if the uveitis results in glaucoma

If left untreated, uveitis can lead to complications such as glaucoma, cataracts, and even blindness. Therefore, prompt veterinary care is crucial if you suspect that your cat may have uveitis.

Treatment For Uveitis In Cats

Treatment for uveitis in cats typically involves identifying and addressing the underlying cause of the inflammation, as well as providing symptomatic relief. If an underlying systemic disease is found, treatment will focus on getting this under this control.

Treatment will differ depending on the the exact condition and may include prescription medication such as anti-inflammatory drugs, corticosteroids, or antibiotics, as well as eye drops or ointments to reduce pain and inflammation in the affected eye.

Glaucoma In Cats

Feline glaucoma is a condition characterized by increased pressure within the eye that can damage the optic nerve and lead to vision loss.

The eye produces a fluid called aqueous humor that helps maintain the shape and pressure of the eye. The fluid is produced by the ciliary body, a structure located behind the iris, and flows through the pupil and into the front chamber of the eye.

From there, it drains out of the eye through a mesh-like structure called the trabecular meshwork, which is located at the junction of the iris and the cornea.

In glaucoma, the drainage of the aqueous humor is impaired, leading to an accumulation of fluid and increased pressure within the eye. The increased pressure can damage the optic nerve, which transmits visual signals from the eye to the brain, leading to vision loss or even blindness

Causes Of Glaucoma In Cats

There are two types of feline glaucoma: primary and secondary.

Primary glaucoma is a relatively rare hereditary condition in cats that occurs due to a genetic defect that impairs fluid drainage from the eye. This defect causes the eye’s fluid to build up, leading to increased pressure and potential damage to the optic nerve.

Primary glaucoma can occur in one or both eyes and is most common in certain breeds such as Siamese, Persian, and Burmese.

Secondary glaucoma, on the other hand, is caused by an underlying condition that affects the eye’s drainage system, leading to increased pressure within the eye. Conditions that can cause secondary glaucoma in cats include inflammation of the eye (uveitis), tumors, cataracts, and trauma.

Symptoms Of Glaucoma In Cats

Like uveitis, glaucoma in cats can be quite painful but early symptoms will likely be missed since cats are so good at hiding their pain. Glaucoma is often well advanced before owners notice their pet’s discomfort.

Glaucoma can occur in one or both eyes. Owners often first notice something amiss because one eye appears different than they other (which can happen even when both eyes are affected).

Symptoms of feline glaucoma may include:

  • Redness or bloodshot appearance of the eye
  • Cloudy or blue-colored eye
  • Excessive tearing or discharge
  • Squinting or closing of the eye
  • Changes in the size or shape of the pupil
  • One eye appearing larger than the other

Treatment For Glaucoma In Cats

Because cats hide their pain so well, the disease is often quite advanced and they may have lost their vision by the time they are seen by a veterinarian. In these cases, treatment is focused on management of pain.

Options for managing pain in cats with glaucoma may include nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, or other pain-relieving medications. These medications can help reduce inflammation and pain in the affected eye, and they may be administered orally or applied topically to the eye. Surgery may be recommended to remove the eye altogether.

Cats that still have vision in affected eyes will receive treatment focused on reducing the pressure in the eye. This may include medications to reduce fluid production and/or improve fluid drainage from the eye.

Treatment for glaucoma can also involve laser therapy or surgical intervention to create a new pathway for fluid drainage from the eye. This can help relieve pressure in the eye and reduce pain.

Underlying conditions will also by treated; however, by the time the damage occurs the glaucoma often irreversible and long-term treatment will be needed to manage it.

Corneal Ulcers In Cats

Corneal ulcers in cats are a common eye condition that affects the cornea, which is the clear outer layer of the eye. Corneal ulcers occur when there is damage or abrasion to the cornea, resulting in an open sore.

These ulcers can be superficial, affecting only the outer layers of the cornea, or they can be deep, affecting the deeper layers of the cornea. In severe cases, they can become so deep that they penetrate the cornea entirely.

Causes Of Corneal Ulcers In Cats

Feline corneal ulcers are often a result of trauma or injury to the eye. Cats that spend time outdoors are at higher risk of developing corneal ulcers due to exposure to foreign objects, plants, or fights with other animals.

Cats that have underlying eye conditions, such as dry eye or entropion, are also more susceptible to developing corneal ulcers. In addition, infections caused by bacteria, viruses, or fungi can also cause corneal ulcers in cats.

Feline herpesvirus is a common cause of corneal ulcers in cats, as it can cause inflammation of the eye and lead to the development of ulcers.

Systemic diseases such as diabetes, hyperthyroidism, and other metabolic disorders can also increase the risk of corneal ulcers in cats. These conditions can affect the health of the eye and increase the likelihood of developing ulcers.

Symptoms Of Corneal Ulcers In Cats

The cornea is very sensitive, and corneal ulcers in any species are extremely painful. They can be difficult to see, requiring the use of a special eye examination called fluorescein staining to identify them.

The most common symptoms of corneal ulcers in cats include:

  • Redness and inflammation of the eye
  • Excessive tearing or discharge from the eye
  • Squinting or holding the eye closed
  • Sensitivity to light
  • Cloudiness or whiteness of the cornea
  • Pain when touching or examining the eye
  • Small depression – if the ulcer is large enough, you might be see a small divot in the cornea

Treatment Of Corneal Ulcers In Cats

The treatment of corneal ulcers in cats depends on the severity and underlying cause of the ulcer.

The primary goal of treatment is to reduce pain and inflammation, promote healing, and prevent further damage to the cornea. Treatment typically involves a combination of topical and/or oral medications and may include surgical intervention in some cases.

Topical medications, such as antibiotics and anti-inflammatory drops, are often prescribed to help prevent infection and reduce inflammation. An ophthalmic ointment may be prescribed to help protect the cornea and promote healing. Pain relief medication may also be prescribed.

If the corneal ulcer is deep or non-healing, or if there is a significant risk of vision loss, surgical intervention may be necessary. Surgery may involve removing damaged or diseased tissue from the cornea or performing a conjunctival graft to promote healing.

Cataracts In Cats

Although cataracts themselves are not painful, cats with cataracts may have underlying causes for the cataracts that cause them pain. Thus, cats with cataracts may also have red eyes.

Cataracts are a common cause of vision loss in cats, resulting when the lens of the eye becomes cloudy or opaque. This opacity blocks light from passing through the lens, leading to vision loss and, in some cases, blindness.

Causes Of Cataracts In Cats

Cataracts in cats can be caused by a variety of factors, including genetics, aging, trauma, underlying medical conditions such as diabetes or hyperthyroidism, exposure to toxins or radiation, and certain medications.

Some breeds of cats, such as the Persian and Siamese, are also more prone to developing cataracts.

Symptoms Of Cataracts In Cats

The most common symptom of cataracts in cats is a cloudy or opaque appearance to the eye. Other symptoms may include:

  • Decreased vision: Your cat may bump into objects, misjudge distances, or have difficulty finding their food or water dishes.
  • Difficulty seeing in low light conditions: Cats with cataracts may have difficulty seeing in low light conditions or in dimly lit rooms.
  • Changes in behavior or activity levels: Cats with cataracts may become less active or less interested in playing or exploring. They may also become more clingy or vocal, as they seek comfort and reassurance.
  • Eye discomfort or pain: In some cases, the underlying cause of the cataracts can cause eye discomfort or pain, which can cause your cat to paw at their eye or rub their face against objects.
  • Red eyes: This is often the first thing that owners notice in cases of cataracts that have underlying causes that result in pain.

Treatment For Cataracts In Cats

The treatment options for cataracts in cats depend on the severity of the cataract and the degree of visual impairment.

Here are some common treatments for cataracts in cats:

Surgery: Surgery is the most common treatment for cataracts in cats. The affected lens is removed and replaced with an artificial lens.

Management of underlying conditions: In cases where the cataract is caused by an underlying condition, managing the underlying condition may help slow the progression of the cataract and preserve vision.

Environmental modifications: If surgery or medical management is not an option, environmental modifications may be helpful in managing the condition and improving quality of life for affected cats. For example, you can use textured mats or rugs to help your cat navigate slippery surfaces, and place food and water dishes in easily accessible locations.

Eye drops: In some cases, eye drops may be prescribed to help manage any inflammation or discomfort associated with the cataracts.


Red eyes in cats can be caused by a variety of conditions, many of which can be serious and require prompt veterinary attention. Conjunctivitis, uveitis, glaucoma, corneal ulcers, and cataracts are all common eye problems in cats that can cause redness and other symptoms.

Recognizing the signs of these conditions and seeking prompt veterinary care can help ensure that your cat receives the appropriate treatment and that any underlying health problems are addressed.

With proper care and management, many cats with eye problems can enjoy good vision and a high quality of life. If you notice any unusual symptoms in your cat’s eyes, it’s always best to consult with your veterinarian for a proper diagnosis and treatment plan.

Disclaimer: This article is intended for information purposes only, and does not constitute medical advice. Always consult your veterinarian if you have specific concerns about your pet’s health.


  • Dr. Wendy Wilkins, DVM, PhD

    Dr. Wendy Wilkins is an experienced veterinarian and epidemiologist with over 20 years of expertise. She holds a Doctor of Veterinary Medicine (DVM) degree and a Doctorate in Epidemiology from the University of Saskatchewan. Throughout her career, Dr. Wilkins has excelled in clinical practice, academia, research, and regulatory veterinary medicine. She is a respected voice in knowledge dissemination, delivering factual information in a readable and understandable manner through articles, books, and public engagements.

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