The dog's eye is definitely an organ with several parts, each uniquely adapted to satisfy the special needs of the dog. The eyeball is seated in a bony socket and guarded with a cushion of fat. Muscles surrounding the eyeball close the eyelids tightly in reaction to pain, irritation, and objects approaching the eye. This will make it hard to examine the top of the eye for injuries and foreign bodies.
The big, clear window in front of the eye may be the cornea. Bordering it's a narrow rim of white ligament known as the sclera, that is much less conspicuous in dogs than in humans. The sclera surrounds and props up entire eyeball. In certain breeds the sclera might be pigmented or spotted.
The round opening in the center of the eye may be the pupil. Round the pupil is really a sphincterlike muscle known as the iris. Just like a shutter on the camera, the iris opens and closes to manage the quantity of light that enters the eye. The iris offers the pigment that provides the eye its color. While most dogs have eyes that really are a shade of brown, blue eyes are normal for many breeds and colours and also have normal vision. In some Northern breeds and dogs using the merle pattern, odd eyes (one brown and one blue) aren't uncommon.
A pinkish membrane known as the conjunctiva covers the white of the eye and doubles to cover the inside of the eyelid. This membrane contains arteries and nerve endings. When inflamed, the conjunctiva appears red and swollen.
The eyelids are tight folds of skin that offer the front of the globe. Eyelashes will always be present on the upper eyelids, although not on the lower eyelids. You will find small hairs on the edge of the lower lids.
Your dog comes with an important third eyelid, the nictitating membrane, located in the inner corner of the eye. This third eyelid is generally inconspicuous, however when it extends over the surface of the eye, it's as though the eyeball has rolled back to its socket.
Tears are secreted by the lacrimalglands. Each eye has two lacrimalglands: one underneath the bony ridge at the very top of the eye socket and also the other integrated into the 3rd eyelid. Tears are conveyed towards the surface of the eye by small ducts that empty behind the lids. Tears avoid the cornea from becoming dry. Additionally they contain substances that fight infections. Tears help eliminate any irritating substances or foreign bodies that come in connection with the eye.
Tears gather in the inner corner of the eye and therefore are carried by the nasolacrimal ducts in to the nasal cavity close to the front of the nose. The inner eye has three fluid-filled chambers. The anterior chamber is located between your cornea and also the iris. The little posterior chamber lies between your iris and front of the lens. The big vitreous chamber, containing a definite jelly, fills the cavity behind the lens and in front of the retina.
The lens is held in place with a number of strands known as the suspensory ligaments. These affix to the ciliary body, a structure made up of muscle, ligament, and arteries. The ciliary body secretes the fluid that fills the anterior and posterior chambers. Contraction of the ciliary muscles changes the curvature of the lens, which enables images of objects at different distances to become focused to the retina.
Light enters the eye by passing with the cornea and anterior chamber and then with the pupil and lens. It then travels with the vitreous and it is received by the retina. The retina is really a layer of photoreceptor cells that convert light into electrical impulses. These impulses are then carried towards the brain through the optic nerves.
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Note: This article was sent to us by: Norma Richards at 05132011
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