If a cat has one pupil bigger than the other for more than an hour, I would recommend getting the cat checked out by a vet. There may be a neurological problem, and the sooner your cat sees a veterinarian, the better for the long-term health of the animal.
Unlike human eyes, which work best in daylight, the cat's eyes function well in extremely low light condition and as such are well suited to an animal that is predominantly crepuscular (most active at dawn and dusk). In darkness, cats eyes are able to function in approximately one-sixth of the light needed for human vision. However they must also be able to function well in daylight - so just how is this achieved.
In low light levels the cats pupil are able to open as wide as possible, but in bright sunlight they are also able to contract to very small size to protect the sensitive retina in bright sunlight. In human eyes, this size variation of the pupil is controlled by a circular ciliary muscle, but this limits the amount of size variation. In cats however, the same process is controlled by two, shutter-like ciliary muscles, which gives the cat it's characteristic slit-like pupil in bright light conditions. All cats pupils are therefore elliptical, however some, notable the 'Big Cats', appear more circular when dilated.
The size of the cats eye is relatively larger than those found in humans; this enables a larger pupil and therefore more light to enter the eye. Generally, the lens is more curved enabling sharper focusing even at the edges of the lens. The size of the anterior chamber and the curvature of the cornea is also greater, which helps more light to be refracted onto the light-sensitive retina.
Another feature, which enabled the amount of light hitting the retina to be increased, is the tapetum lucidum. This is positioned at the back of the eye, behind the retina and acts like a mirror, reflecting light back onto the light sensor cells in the retina. This gives the cats eyes the characteristic night-time glow when they are caught in a beam of light.
There are two distinct types of light receptor cell on the retina - Cones, which are sensitive to high levels of light, used in colour vision and Rods, sensitive in low light conditions. In cats, there is a greater concentration of Rods, aiding their night-time vision. As in humans, there is a greater concentration of receptor cells at the centre of the eye, leading to the optic nerve. In cats, however, these a concentrated along a broader, horizontal band. This gives the cat far more sensitivity to movement along the horizontal axis and they are therefore more able to detect prey movement along the ground at greater distances.
sometimes they are just born with it but sometimes there is a problem
It means that they are about to attack.
Cats pupils adjust just a little slower than humans pupils.Actually the answer above is not correct at all. Cats eyes adjust almost faster than humans. The reason being, because they are going to fight or are scared/frightened there pupils grow on will. If the room is too bright they pupils will grow to very thin slits. When nothing is wrong with the cats there pupils are normal, like a perfectly smooth rhombus.
It helps the pupil let in the right amount of light.
because some cats have a weird history like heritage problems and it causes them to have round pupils, especialy if its a big cat like a Maine coon or a Persian.
Outside and at night, all they need is the stars.
The darker the room your cat is in, the larger it's pupils will get to allow more light into the eye. But I notice though, when my cat wants to pounce something, her pupils will get bigger also. A cats pupils change size not only because of light, but also because of mood. When prey (which if your cat is indoor might just mean a toy mouse) comes by, its pupils will dilate to get a better view of prey.
Animal pupils come all different shapes and sizes. A cat has slit shaped pupils, and a chicken has round pupils. Some goats even have time glass shaped pupils. Many different shapes.
Abviously not. Hence tha pupils changing size.
Cats pupils adjust just a little slower than humans pupils.Actually the answer above is not correct at all. Cats eyes adjust almost faster than humans. The reason being, because they are going to fight or are scared/frightened there pupils grow on will. If the room is too bright they pupils will grow to very thin slits. When nothing is wrong with the cats there pupils are normal, like a perfectly smooth rhombus.
I'm sure all shapes
Are you talking about the pupils look straight in the am and then look like a circle in the afternoon? This could possibly be do to constriction and dilation of the pupils with adjustments to how light it is out....
No Warrior Cats have brown eyes, because simply... cats cannot have brown pupils! The closest thing to brown cats can have is amber.
It helps the pupil let in the right amount of light.
Because of thier shapes
because some cats have a weird history like heritage problems and it causes them to have round pupils, especialy if its a big cat like a Maine coon or a Persian.
Like many animals, cats have large pupils (slit pupils in domestic cats) and a tapetum lucidum, a tissue layer behind the retina that reflects light back through the optical sensors. These improve their night vision. (The tapetum is the source of cat's "glowing eyes" at night.)
Cats eyes can spot predators because they have large pupils which adjust to darker situations easier. This allows cats to spot their prey in dim conditions.
Not in most fish, but flat fish and eel pupils change in size according to the amount of light they receive - like humans, these fish's pupils become smaller when there is plenty of light.