Have you ever seen cats with different colored eyes? Two different colored eyes, also called heterochromia, are more likely to occur in certain breeds of cats .
Cat eyes can be of many colors , from gold to copper, orange, green and blue. Interestingly, the eyes of cats are always light in color – cats do not have dark brown eyes, like dogs or people.
Sometimes cats have different colored eyes. This striking phenomenon, called heterochromia, can also occur in dogs and even people.
Heterochromia in cats can give rise to any combination of eyes, such as a blue and a green eye, or a gold and a blue eye, etc.
The anatomy of cat eyes
Cat eyes are extraordinary. Let’s take a look to see for ourselves and find some answers in science! Cats eyes are significantly large compared to the size of their head. This is a key characteristic of all nocturnal animals.
The actual eyeballs are placed in the bony cavities called orbits. The white part of the eye is the sclera and is covered with a thin membrane that functions as the conjunctiva. The conjunctiva covers the inside of the eyelids. In front of the eye there is a light cupola dome. The cornea protects the eye and lets light in. The round, colored area of the eye is the iris.
Light enters the eye through the pupils (the black area in the center of the eyes). Heterochromia cats are very sensitive to changes in light and adjust accordingly. In the great abundance of light, the cat’s pupils appear elliptical, while in darker conditions they are round, almost filling the entire iris area. The smaller the pupil, the less light enters, and vice versa.
Domestic cats present with vertically slit pupils. However, there are some big cats, like Siberian tigers, that have circular pupils, similar to us. The characteristic of vertical eyes is accepted as an adaptation to a nocturnal lifestyle, since the shape of this pupil excludes light more effectively. Vertical pupils also change size much faster than round pupils.
Behind the iris is the lens. Align the back of the eye with the retina of the light-sensitive tissue. Light is focused on the retina through the cornea, pupil, and lens. It is the retina that will convert light rays into nerve impulses and send them to the brain.
What breeds of cats are likely to have heterochromia?
Heterochromia in cats is common in certain cat breeds such as British Shorthairs , Cornish and Devon Rex, Japanese Bobtails, Munchkins , Persians, Scottish Folds, Siamese, Sphynxes, and Turkish Angoras . It is also common in white cats of any breed .
Causes of heterochromia in cats
Different colored cat eyes can be inherited from parents (genetic) or acquired due to certain diseases , injuries, and medications . Acquired strange eyes cannot be passed on to kittens. However, most of the time, strange eyes are congenital (associated with developmental defects).
How does heterochromia occur?
This usually occurs in cats with white or light spots (bicolor and tuxedo). The dominant white gene (the gene that makes cats completely white) and the white spots gene (the gene that causes cats to have white spots) sometimes interfere with the migration of melanocytes to one of the eyes. This condition does not occur very often in cats that lack these two genes. In cats of different colors , the strange eyes are often the result of differently developed eyes in the embryo.
The iris is the colored part of a cat’s eye. The color of the iris is determined by the presence of pigment, also known as melanin. Therefore, a cat with different colored eyes has a condition in which the iris of one eye is different from the other iris.
Types of heterochromia in cats
Heterochromia can be inherited, congenital, or acquired. It can occur in three different ways: complete heterochromia (one eye is a completely different color than the other), central (different colors within the iris that give a spiky or halos appearance) or sectorial (part of the cat’s iris is blue and the rest of that eye is a different color). Complete heterochromia is the most common form.
– Inherited heterochromia
This type is mainly found in epistatic white cats (epistatic means that the cat is genetically of another color, such as black or gray, but is hidden by the white masking gene) or in bicolor cats , due to the white spotting gene.
– Congenital heterochromia
It may be due to mysticism in which two distinct populations of cells arise from a fertilized egg, or chimerism in which two zygotes fuse early in the developmental stage.
– Acquired heterochromia
Acquired heterochromia can be due to uveitis (inflammation of the middle lamina of the eye, which is located between the retina and the sclera), certain medications, tumors of the iris, and trauma.
What should you do if you notice a change in the colors of your cat’s eyes?
If you notice a color change in your cat’s eyes or if you suspect that your cat’s eyes are bothering her, take her to the vet for an eye exam.
Other conditions that can cause eye color changes that are not associated with heterochromia can include cataracts, glaucoma, corneal dystrophy, uveitis, nuclear sclerosis, underdeveloped optic nerve, and retinal dysplasia.
Does heterochromia in cats cause other medical problems?
White cats with one or more blue eyes have a higher incidence of congenital deafness, but these cats are not more prone to blindness than other cats.