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Understanding Senior Eyes in Pets

Understanding Senior Eyes in Pets

“Senior pets” refer to cats above 10 years old, and dogs in the last ~25% of their breed’s estimated lifespan. As your pets approach their golden years, you may worry about them developing health issues that you may not be able to detect … until it’s too late.

Do you want to avoid such helplessness and manage your pet’s health proactively? We can help you! Eyes aren’t just windows to the soul – they can shine a light on your pet’s health!

This article describes what healthy eyes look like in pets. This article also describes the abnormal physical changes to look out for in pets’ eyes, what these changes may indicate and what you can do about it.

*What do healthy eyes look like?

In order to know what is abnormal, it’s important to know what’s normal! Here are the traits of eye-deal, healthy eyes:

  • Fully open (no squinting!)
  • Black, equal pupils

    “Pupils” are the black circles in the centre of the eyes. The pupils enable light to enter the eyes. Normal pupils should be jet-black, without any discolouration!

    Pupils can contract or expand. This regulates the amount of light that enters the eyes. However, normal pupils should be equal in size. Normal pupils should also be located at the centres of the eyes.
  • No discolouration in the whites of the eyes​​​​​​​​

    “Sclera” is the scientific term for the whites of the eyes. It’s normal for the sclera to have thin, faint red lines. These are the blood vessels that supply the eyes. Other kinds of discolouration require veterinary advice!
  • Clean, with minimal to no discharge​​​​​​​​

    It’s normal for some breeds to have a small amount of clear discharge (aka tear stains), due to the shape of their tear ducts.

What abnormal changes can happen in elderly pets’ eyes?

It can be easy for anxious paw-rents to get overwhelmed with scientific jargon! Therefore, we don’t expect you to memorise a list of conditions. This article does not include a complete list of eye conditions that senior pets can have (nor does it aim to!)

Also, this information is NOT meant to help you to diagnose your pet by yourself! We aim to equip you with the knowledge to spot the red flags, so that you can promptly consult a vet and let them diagnose your pet!

Here are the red flags to look out for:

  • Cloudy pupils

    What this could mean:

    Normal ageing

    Behind the pupil is the lens. The lens focuses light and help animals (and humans!) to see. It is common for the lens to harden with age. Fibre accumulates in the outer layers of the lens and compresses the lens’ inner layers. This gives rise to blueish-grey lens.

The scientific term for this condition is “Nuclear Sclerosis”. It is an age-related condition. It does not significantly affect vision, nor does it worsen enough to become dangerous. Nuclear sclerosis does not require treatment.

However, please do NOT assume that cloudy pupils in elderly pets are not serious! Without diagnostic tests, it is easy to confuse nuclear sclerosis with more sinister conditions. Read on to learn what they are…


Cataracts result when protein accumulates in the lens and forms clumps. While it is an age-related condition, certain breeds (e.g. Toy Poodles, Shih Tzus, Yorkshire Terriers) are more vulnerable. Diabetic pets are also more likely to develop cataracts. Cataracts block light that passes through the lens. Thus, they can affect vision and even cause blindness.

Cataracts can happen in one or both eyes. They vary in severity – from small, pinprick cataracts, to cataracts that cover the entire pupil. Their behaviour is unpredictable. They can be non-progressive, progress slowly or progress really quickly.

Cataracts can cause permanent blindness if left untreated. Untreated cataracts can also cause inflammation within the eye, which can block fluid drainage in the eye. This causes a dangerous condition called glaucoma (more about glaucoma later!) Once cataracts develop, cataract surgery is the only accepted way to remove them. However, pets may not be suitable for surgery if complicating factors (e.g. glaucoma) are present.

Corneal ulceration

The cornea is the transparent, protective outer layer of a healthy eye. When there is a corneal ulcer, fluid accumulates within the cornea and causes a cloudy appearance.

Corneal ulcerations can occur in pets of any age, including older animals. There are a few causes of corneal ulceration – including trauma and irritation.

These conditions have very different treatment, and only be differentiated with tests at a vet. If you see cloudy eyes in your senior pet, please consult a vet promptly!

  • Swollen eyeballs

    A swollen eyeball is a serious medical issue. Here are the potential reasons in elderly pets:


    The inside of a healthy eye is filled with fluid that nourishes it and contributes to its shape. In a healthy eye, excess fluid is drained into the bloodstream. Glaucoma refers to abnormally high fluid pressure within the eye. In animals, it occurs due to inadequate drainage from the eye. There are two types of glaucoma – primary glaucoma (due to inherited abnormalities within the eye) and secondary glaucoma (glaucoma due to injury or disease).

There are several reasons for secondary glaucoma (e.g. hypertension, cataracts, cancers inside the eye). Hypertension is more common in older cats and dogs.  In older pets,  hypertension occurs because of age-related conditions such as kidney disease and heart disease (as well as thyroid disease in cats).  Cancer is also more common in older pets. The American Veterinary Medical Association (AVMA) estimates that almost half of dogs over the age of 10 have cancer!

Glaucoma is a medical emergency. Without prompt treatment, pets can go blind!

Prolapsed Eye

A “prolapsed eye” is an eye that is partially or fully out of its socket. It usually occurs because of damage to the eye socket, although some bug-eyed breeds (e.g. pugs, bulldogs) are prone. Pets all of ages are vulnerable – including older pets!

  • Cross-eyed expression

It is concerning if one or both eyes are pointed in an abnormal direction, and/or if eye movement is not coordinated. The scientific term for this is “strabismus”. Strabismus usually occurs because of problems with the muscles controlling the eye, and/or issues with nerves that control the eye muscles. There are many causes of strabismus in pets – including brain, eye and nerve cancers in older pets!

  • Unequal pupils

    Pets with eye cancers or glaucoma can develop unequal pupils. Unequal pupils can also occur for other reasons (e.g. nerve damage, infection)

  • Bleeding

    Bleeding can occur within the eye, or from the eye. Internal bleeding is caused by serious conditions that can affect all animals (e.g. poisoning, infections, physical trauma). It can also occur because of cancer or hypertension (which older animals are prone to!)

    If your pet appears to have a blood-filled eye, please contact an emergency vet asap!

  • Other general symptoms (redness, inflammation, squinting, excessive discharge and scratching at eyes)

    Redness and inflammation could indicate a wide range of eye conditions – including the ones that have been discussed above (cataracts, corneal ulcers, glaucoma etc)! Other potential conditions include (but are not limited to):

    -Eye infection (commonly accompanied by yellow/green discharge)
    -Dry eye (a chronic disease that causes inadequate tear production)

As eye conditions are generally uncomfortable and painful, it is common for affected animals to squint and scratch at their eyes.

How can I take charge of my pet’s eye health?

  • Monitor your pet regularly

    You now have a good excuse for gazing lovingly at your pet! If you regularly eye-ball your pet’s appearance and activity, there is a higher chance of spotting subtle signs that a vet can investigate further.
  • Be diligent about routine vet visits

    All pets should go for a yearly vet visit. Senior pets should go for a vet visit and diagnostic tests every six months. Trained vets can spot red flags that paw-rents may miss . Tests can also spot early-stage health issues (e.g. hypertension, kidney disease) that cannot be detected with just a physical exam. It’s important to spot diseases early and manage/treat them before it is too late!
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