Below is information about the structure and functions of eyes. We’ll explain the general structure of a cat’s eyes and how they work.
What Are Cat’s Eyes?
Cat’s eyes are receptors for special vision.
Where Are Cat’s Eyes Located?
Cats have two eyes, positioned on either side of their face. There’s quite a bit of variation in the position, size (including the bony sockets of the eyeballs), and the size and shape of the eyelid slits (the openings between the eyelids) among different animal species. In felines, these structures are very consistent, although in some breeds, like Persian cats and Burmese cats, their eyes seem to stick out more from the skull, and the openings appear larger.
What Is the General Structure of a Cat’s Eyes?
A cat’s eyes are made up of three concentric layers or tissue layers: the outer fibrous layer, the middle vascular layer, and the inner nerve layer. The fibrous membrane is the outermost layer of the eye, consisting of the sclera (the white part of the eye) and the cornea (the transparent cover at the front of the eye). The vascular layer is the thicker middle layer, usually called the uvea. It includes the choroid (a thin, dark layer of blood vessels behind the retina), the ciliary body (which produces fluid in the front chamber of the eye and helps support the lens), and the iris (the tissue that makes up the pupil). The pupil is the opening (or black dot) in the center of the iris, primarily regulating the amount of light the eye receives. The inner nerve layer at the back of the eye is the retina. The retina works like the film in a camera, sending electronic images to the brain through the optic nerve.
Inside a cat’s eye, there are three chambers: the anterior chamber, the posterior chamber, and the vitreous body. The anterior chamber is between the cornea and the iris and contains aqueous humor (a clear fluid produced by the ciliary body). The posterior chamber is between the iris and the lens and also contains aqueous humor. The vitreous body is behind the lens and in front of the retina. It’s a gel-like substance that helps keep the eye’s shape.
Other Important Structures of a Cat’s Eyes Include:
- Orbital Socket: The bony cavity that holds and protects the eyeball.
- Eyelids: Extensions of the facial skin that protect the eyes. The outer surface of the eyelids is covered with skin, while the inside has a thin, whitish membrane called the conjunctiva.
- Third Eyelid: Originates from the inner corner of the eye, containing strong cartilage support and tear glands. It’s an extra protective mechanism designed for a cat’s eyes.
- Conjunctiva: A thin, almost transparent, vascular tissue that covers the white part of the eye and the eyelids.
- Lens: A soft, transparent, spherical structure floating inside the eye just behind the pupil. The lens is mainly responsible for focusing light that enters through the pupil onto the retina at the back of the eye.
- Tear Gland System: Includes the lacrimal glands and the tear glands of the third eyelid, responsible for producing tears and draining them from the eye.
What Are the Functions of a Cat’s Eyes?
The function of a cat’s eyes is to provide vision. The ability to see depends on the activity of several structures inside and around the eyeball. When a cat looks at an object, light reflects off the object onto the cornea. The cornea bends the light, which then passes through the pupil into the lens, and through the vitreous body to the retina.
The lens ensures that the light is clearly focused on the retina. The image formed on the retina is upside down, and it’s the brain’s job to flip the image so the cat sees it correctly. The retina contains millions of light-sensitive cells called rods and cones. Rods are sensitive to dim light, while cones are sensitive to bright light and color. The retina converts light energy into electrical signals, which are sent to the brain through the optic nerve—the pathway from the eye to the brain. In the brain, these electrical signals are transformed into images that can be perceived upright.
