The short answer
A slow wink or blink is a genuine sign of trust and affection — the feline equivalent of a smile or “I love you.” (A persistent one-eye squint, though, can mean an eye needs cleaning or is irritated.)
A cat closing one eye at you is usually one of two completely different things: a genuine social signal, or an eye problem. Telling them apart takes about five seconds and is worth knowing, because one needs a vet.
The slow blink, which is the real signal
What owners describe as a wink is most often a slow blink — the cat meets your gaze, narrows its eyes, and closes them slowly, sometimes not quite symmetrically, before reopening.
Between cats, a hard unbroken stare is a threat signal. Deliberately narrowing or closing the eyes removes that content — it is the feline equivalent of unclenching. A cat that slow-blinks at you is actively signalling that it is comfortable and that you are not a problem.
It works in both directions, which makes it one of the few pieces of cat communication you can genuinely use. Meet your cat's gaze, narrow your eyes slightly, and close them for about a second. Many cats reciprocate. It is particularly useful with nervous or newly adopted cats, where the instinct to stare warmly at them is exactly the wrong move.
Why it can look like a wink
Slow blinks are often asymmetric. One eye closes slightly ahead of the other, or one closes more fully, especially when the cat is drowsy or lying with one side of its face against something.
Cats also blink one eye when something momentarily irritates it — a draught, a speck of dust, a whisker touched at the wrong angle. Brief, occasional, and immediately back to normal is unremarkable.
How to blink back properly
Do not stare first and then blink — that reads as a stare with a pause in it. Look at the cat with soft, slightly narrowed eyes from the start, then close them slowly for around a second and reopen just as slowly. Turning your head very slightly to the side rather than facing the cat square-on makes it more effective again, because full frontal orientation is itself mildly confrontational.
When one eye closing is a medical sign
This is the distinction that matters. A social slow blink is symmetrical enough, brief, and the eye returns to fully open and normal-looking. It happens in relaxed contexts and stops when the cat gets up.
A cat holding one eye partly or fully closed — squinting, blepharospasm — is a different picture entirely, and in cats it usually means pain. The eye may water, the third eyelid may show across the corner, the cat may paw at it or rub that side of its face on furniture.
Common causes include:
- Corneal ulcer, which is genuinely painful and can deteriorate quickly.
- Conjunctivitis, often associated with feline herpesvirus, which frequently reactivates during periods of stress.
- A foreign body — a grass seed or piece of grit under the lid.
- Trauma, including a scratch from another cat.
- Uveitis or glaucoma, both of which are serious and can threaten vision.
Squinting is not winking — get it checked
See a vet promptly if your cat holds one eye partly or fully closed, if the eye is watering or has discharge, if the third eyelid is visible across the corner, if the eye looks cloudy or the pupil is a different size to the other, or if your cat is pawing at it or shying from light. Cats hide pain well and eye conditions can deteriorate fast — corneal ulcers in particular can progress within a day or two. Do not use human eye drops, and do not use any leftover medication from a previous problem: steroid drops can cause serious damage if an ulcer is present.
The short version
Both eyes, slow, symmetrical, in a relaxed cat, followed by normal open eyes: that is a compliment, and you can return it.
One eye, held closed, in any context: that is your cat telling you something hurts, and it needs looking at rather than admiring.
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Frequently asked
Why does my cat wink at me?
What looks like a wink is usually a slow blink, often slightly asymmetric. Between cats a hard stare is a threat, so narrowing and closing the eyes removes that content — it is a deliberate signal that your cat is comfortable with you.
Should I wink back at my cat?
Slow blink back rather than winking. Look with soft, slightly narrowed eyes from the start, then close them slowly for about a second and reopen slowly. Turning your head slightly to the side helps, since facing a cat square-on is mildly confrontational.
How do I tell a slow blink from squinting?
A slow blink is brief, roughly symmetrical, happens in a relaxed context, and the eye returns to fully open and normal-looking. Squinting is one eye held partly or fully closed, often with watering, discharge, or the third eyelid showing.
Is my cat closing one eye an emergency?
It needs prompt attention. Persistent closing of one eye usually means pain, and causes include corneal ulcer, conjunctivitis, a foreign body, trauma, uveitis and glaucoma. Corneal ulcers can deteriorate within a day or two.
Can I use eye drops on my cat?
Not without veterinary advice, and never leftover medication from a previous problem. Steroid drops in particular can cause serious damage if a corneal ulcer is present, and human eye products are not appropriate for cats.
Why does my cat slow blink more at some people?
It is a comfort signal, so cats direct it at people they feel relaxed around. It is especially worth using deliberately with nervous or newly adopted cats — where the human instinct to gaze warmly at them is precisely the wrong move.
Sources
Every claim on this page is checked against published veterinary and animal-behaviour research. Here’s where it comes from.
- 1Social organization in the cat: a modern understanding — Journal of Feline Medicine and Surgery (via PubMed Central)
- 2Feline Behavior Problems: Aggression — Cornell Feline Health Center
- 3Common Cat Behavior Issues — ASPCA
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