Eye problems in cats can go from mild to serious quickly, and cats are good at hiding eye pain. A little clear tearing during a cold may settle on its own, but squinting, a cloudy eye or sudden blindness can threaten your cat’s sight within hours. Knowing which signs need a vet the same day helps you act in time.
Quick answer: Squinting, redness, discharge, cloudiness, a visible third eyelid or pawing at the eye are signs of an eye problem. Common causes include herpesvirus infection, conjunctivitis, corneal ulcers and, in older cats, high blood pressure. Squinting that lasts more than a few hours needs a vet visit. A cloudy eye, a suspected ulcer, or sudden blindness with large pupils is an emergency. Never use human eye drops on your cat.
Signs of eye problems
- Squinting or keeping one eye closed
- Watery, sticky, yellow or green discharge
- Red or swollen eyelids or the pink tissue around the eye
- The third eyelid (a pale membrane in the inner corner) showing across the eye
- Pawing or rubbing at the eye
- A cloudy, blue or white look to the eye
- Changes in the color of the iris, or dark spots
- Pupils of different sizes
- Bumping into things or seeming unsure where they’re going
Common causes
Herpesvirus and infections
Feline herpesvirus is one of the most common causes of eye trouble in cats. Many cats catch it as kittens, and the virus stays dormant, flaring up during stress or illness. Signs include red, watery eyes and squinting, often with sneezing. It can cause conjunctivitis and corneal ulcers, and some cats have repeated flare-ups. See upper respiratory infection in cats. Vaccines help reduce how severe it is; see the cat vaccination schedule.
Conjunctivitis
Conjunctivitis is inflammation of the pink tissue around the eye. It causes redness, swelling and discharge. Infections are the most common cause in cats, and allergies are less common than many people think. PetMD advises seeing a vet within 24 hours.
Corneal ulcers
An ulcer is a scratch or sore on the clear surface of the eye, from a scratch during play or a fight, a foreign body, or herpesvirus. Ulcers are painful: cats squint, tear up, avoid bright light and may paw at the eye. They can get infected or deepen quickly, so they need an urgent exam.
Problems inside the eye
- Uveitis is inflammation inside the eye, causing redness, squinting, a cloudy look or iris color changes. It’s often linked to infections or other diseases, so finding the underlying cause matters.
- Glaucoma is raised pressure in the eye. It’s painful, can cause rapid vision loss, and is an emergency.
- Cataracts cloud the lens and usually progress slowly.
High blood pressure in older cats
High blood pressure, often linked to kidney disease or an overactive thyroid, can cause bleeding in the eye or the retina to detach, leading to sudden blindness. PetMD notes that blindness can become permanent if treatment is delayed by even a few hours, which is why regular blood pressure checks are valuable in senior cats. See common health problems in senior cats.
Other causes
These include eyelids that roll inward and rub the eye (entropion), lumps on the eyelids, foreign bodies, injuries from fights, and dark spots or changes on the iris that need monitoring by a vet.
How urgent is it?
| What you notice | What to do |
|---|---|
| Sudden blindness, especially with large pupils | Emergency: go now |
| Cloudy or blue eye, or a bulging eye | Emergency: go now |
| Eye injury, or suspected scratch or ulcer | Same day |
| Squinting for more than a few hours | Same day |
| Red eyes with discharge | Within 24 hours |
| Third eyelid showing, iris color change or eyelid lump | Book a vet visit soon |
| Slight clear tearing in a cat that’s otherwise well | Watch closely; see a vet if it lasts or worsens |
Urgent: sudden blindness, a cloudy or bulging eye, an obvious injury, or a cat in clear pain holding an eye shut needs a vet the same day. Delays can mean permanent loss of sight or of the eye.
What you can and can’t do at home
- Do gently wipe away discharge with a clean cotton pad dampened with warm water, using a fresh pad for each eye.
- Do keep your cat indoors and calm, and stop it scratching the eye if you can.
- Don’t use human eye drops, old prescriptions or home remedies. Some steroid eye drops can make an ulcer much worse.
- Don’t wait days to see if it clears. Some mild viral infections settle, but many eye problems need treatment quickly.
Eye pain often shows as squinting and hiding; see signs your cat is in pain. For first aid if your cat injures an eye, see cat first aid basics, and for other warning signs, signs your cat is sick.
Frequently asked questions
Why is my cat squinting one eye?
Squinting usually means the eye is painful. Common causes include corneal ulcers, infections such as herpesvirus, foreign bodies and inflammation inside the eye. If the squinting lasts more than a few hours, see your vet.
Can I use human eye drops on my cat?
No. Human eye drops, especially ones containing steroids, can make some eye problems such as ulcers much worse. Only use eye medicine your vet prescribes for your cat.
Why is my cat’s third eyelid showing?
A visible third eyelid can be caused by eye pain, infection, dehydration, illness or a nerve problem called Horner’s syndrome. If it’s showing for more than a short time, or with other signs, ask your vet to check.
Can cats suddenly go blind?
Yes. In older cats, high blood pressure can cause the retina to detach, leading to sudden blindness, often with large pupils. This is an emergency, as quick treatment gives the best chance of saving some vision.
