Updated September 25, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: Microphthalmia means a cat was born with one or both eyes abnormally small. It develops before birth, from genetics or problems during pregnancy, and there’s no medication that makes the eye grow. Vision ranges from nearly normal to blind depending on how the eye formed. Treatment focuses on related problems such as eye infections, discharge, or pain, and sometimes removal of an eye that’s causing ongoing trouble. Many cats with microphthalmia live happy, normal lives.
What it looks like
- One eye noticeably smaller than the other, or both eyes small
- The eye sits deep in the socket, with the third eyelid often visible
- Squinting, discharge, or frequent eye infections
- Cloudiness in the eye (from cataracts or other defects)
- Bumping into things, or cautious movement, if vision is reduced
Causes
- Genetics: it can be inherited, sometimes along with other eye defects.
- Problems during pregnancy: infections, certain medications, or poor nutrition in the mother can affect how the eyes develop.
- Other birth defects may occur along with it, such as cataracts, a gap in the iris (coloboma), or retinal problems.
Conditions that can look similar
- Phthisis bulbi: an eye that was normal size but shrank after serious injury, infection, or inflammation.
- Enophthalmos: a normal-size eye that sits sunken, from pain, dehydration, weight loss, or nerve problems such as Horner’s syndrome.
Your vet can tell these apart, which matters because they have different causes and treatments.
When to see a vet
Have any kitten with an unusual-looking eye examined, ideally by a veterinary ophthalmologist. See your vet promptly if an eye becomes red, painful, cloudy, swollen, or has thick discharge, or if your cat is squinting or pawing at its face.
How vets diagnose it
Your vet will examine both eyes, test vision and reflexes, and check tear production and eye pressure. An eye ultrasound can measure the eye and look for other defects.
Treatment
- No treatment is needed for a comfortable, infection-free eye.
- Eye drops or ointment prescribed for conjunctivitis or infections.
- Eyelid surgery if eyelashes or lids rub the eye.
- Removing the eye (enucleation) if it’s painful, repeatedly infected, or blind and causing problems. Cats adapt very well afterward.
Home care
- Keep the eye area clean: gently wipe discharge with gauze or a cotton pad moistened with sterile saline, using a fresh pad for each eye.
- Help a low-vision cat: keep furniture, food, water, and litter in the same places, and use rugs or textures to mark areas.
- Keep your cat indoors if its vision is limited.
- Use your voice before touching your cat so you don’t startle it.
- Spay or neuter: affected cats shouldn’t be bred.
What to avoid
- Human eye drops, including redness relievers and allergy drops, unless your vet prescribes them.
- Leftover eye medications, especially steroid drops, which can make some infections and ulcers much worse.
- Tea, chamomile, or homemade eye washes. Use sterile saline if your vet recommends cleaning.
- Treatments that claim to “grow” the eye. There aren’t any.
Frequently asked questions
Can a cat with microphthalmia see?
Some can, some can’t. It depends on how the eye developed. Cats rely heavily on hearing, smell, and whiskers and cope well with limited vision.
Is microphthalmia painful?
Usually not, but related problems like infections or a poorly fitting eyelid can be. Signs of pain include squinting and pawing at the eye.
Will the eye get bigger as my kitten grows?
It may grow slightly, but it will stay smaller than normal.
Sources
- Merck Veterinary Manual: Congenital and inherited anomalies of the eye in cats
- Merck Veterinary Manual: Ophthalmology in small animals
- Gelatt KN (ed.). Veterinary Ophthalmology. Wiley-Blackwell
- American College of Veterinary Ophthalmologists (ACVO): Pet owner information
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.