Cataracts are often associated with elderly people, giving them a stereotypical hazy eyed appearance and contributing to disruptions in eye sight. But what are they? And can they affect our pets too? We know elderly dogs commonly develop cataracts, but what about our feline four legged friends? They might appear in the word, but do they really put the ‘cat’ in cataracts? 

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What are cataracts?

The American College of Veterinary Ophthalmologists (ACVO) defines cataracts as an “abnormality of the lens in which an opacity, or a cloudy change in the tissue, scatters light. Hence, the normal composition of the lens is disrupted and its transparency is lost”.

The lens is a curved structure that sits behind the pupil of the eye, focusing incoming light onto the retina; the structure that receives light and transmits electrical signals to your brain. When the lens becomes cloudy, the pathway of light to the retina is disrupted, meaning changes to the individual’s vision. 

What causes cataracts?

Cataracts develop when proteins in the lens break down, causing abnormal opacities to form. This is often due to age related changes in dogs and humans (‘senile cataracts’) but can occur for a variety of other reasons in much younger individuals, including diabetes, nutrition, and other eye diseases. 

So what about cats? 

Cataracts are less common in cats than they are in dogs and humans, but can nevertheless occur in felines of any age, sex or breed. In contrast to dogs and humans, cataracts in cats most commonly occur as a result of inflammation within the eye (‘uveitis’), or are due to a genetic predisposition (‘inherited cataracts’). Such a predisposition has been observed in Birmans, Himalayans and British Shorthair cats (Narftröm 1999). 

Uveitis is by far the most common cause of cataracts in cats, and is often the result of an underlying disease process, such as Feline Immunodeficiency Virus (FIV), Feline Infectious Peritonitis (FIP) or Feline Leukaemia Virus (FeLV). Uveitis can cause the cat’s immune system to recognise the lens as a foreign object, attacking it and contributing to the formation of a cataract.

What are the signs of cataracts?

Due to the progressive nature of cataracts, cats may not show any symptoms as they may not yet be disrupting the cat’s vision. Cataracts are often an incidental finding at a routine check up with your vet. 

When cataracts become advanced, a cat’s eyes may appear cloudy or hazy and owners may notice their pets behaviour changes, such as becoming more reluctant to go outside or climbing up and down stairs.

It is important however to remember that cataracts are not the only reason cats eyes can become cloudy. Infections, trauma or other age related changes can cause changes to the eyes’ appearance, and only a vet can reliably distinguish between these changes. 

When should you contact your vet?

It can be hard to spot early changes in your cat’s eyes and as cataracts are often related to underlying disease processes in cats, it’s important that your vet is contacted as soon as you notice any changes. It’s also important to ensure your cat visits the vet regularly throughout their life to ensure things like cataracts can be detected early on, and any potential underlying causes can be investigated. 

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How are cataracts diagnosed and treated?

In any species, cataracts are diagnosed using an ophthalmoscope, a special tool used to examine the internal structure of the eye. Once cataracts have been diagnosed in a cat, any potential underlying causes must be investigated via blood and urine tests, a thorough physical examination, and other diagnostic tests. 

Treatment for cataracts involves surgery to remove the cloudy lens. And then replace it with an artificial lens in a procedure known as phacoemulsification. Cataracts cannot be treated with medications, meaning they will not resolve without surgery. However, cataracts themselves are not painful. And if caught early, often do not interfere with the cat’s vision or quality of life. Your vet may not feel your cat is a candidate for surgery. So they may recommend treating any underlying conditions and managing any complications the cataracts may cause; such as glaucoma (increased pressure inside the eye) with topical or oral medications. 

Summary 

Cataracts are an abnormal opacity in the lens of the eye. Unlike in dogs and humans, are often linked to underlying disease processes in cats. 

Regular physical examination by a vet is important to keep a track of your cat’s health and once diagnosed, your vet may recommend surgery to treat advanced cataracts, or may advise you that the condition can be managed with medications alone.

The important thing to note is that cataracts are often secondary to an underlying disease, and diagnosing and treating this is important to prevent further complications.

And remember, cataracts are not the only potential cause of cloudy eyes in cats, so it’s alway better to be safe rather than sorry, and contact your vet. 

References and further reading