Anatomy: Physiology of the Eye
ANATOMY & PHYSIOLOGY of the EYE
Even though the eye is small, only about 1 inch in diameter, it serves a very important function -- the sense of sight. Vision is by far the most used of the five senses and is one of the primary means that we use to gather information from our surroundings. More than 75% of the information we receive about the world around us consists of visual information.
The eye is often compared to a camera. Each gathers light and then transforms that light into a "picture." Both also have lenses to focus the incoming light. Just as a camera focuses light onto the film to create a picture, the eye focuses light onto a specialized layer of cells, called the retina, to produce an image.
- A multichambered, almost spherical structure
- Located in the anterior portion of the orbit
*orbit is the bony structure of the skull that surrounds & protects the eye
I. EXTERNAL LAYER
- Fibrous coat that supports the eye a. SCLERA - a tough, leather-like tissue, also extends around the eye. Just like an eggshell surrounds an egg and gives an egg its shape, the sclera surrounds the eye and gives the eye its shape.The extraocular muscles attach to the sclera. These muscles pull on the sclera causing the eye to look left or right, up or down, and diagonally. * opaque white tissue normal – white * systemic problems – icteric sclera
b. CORNEA – dense transparent layer. The cornea is the transparent, clear layer at the front and center of the eye. It is well supplied with nerve endings. The main purpose of the cornea is to help focus light as it enters the eye. If one wears contact lenses, the contact lens rests on the cornea. normal – transparent, smooth, shiny & bright accident or eye injury – cloudy areas or specks on the cornea
II. MIDDLE LAYER
- Vascular & heavily pigmented a. CHOROID
- lines most of the sclera & is attached to the retina
- contains many blood vessels
- supplies nutrients to
Even though the eye is small, only about 1 inch in diameter, it serves a very important function -- the sense of sight. Vision is by far the most used of the five senses and is one of the primary means that we use to gather information from our surroundings. More than 75% of the information we receive about the world around us consists of visual information.
The eye is often compared to a camera. Each gathers light and then transforms that light into a "picture." Both also have lenses to focus the incoming light. Just as a camera focuses light onto the film to create a picture, the eye focuses light onto a specialized layer of cells, called the retina, to produce an image.
- A multichambered, almost spherical structure
- Located in the anterior portion of the orbit
*orbit is the bony structure of the skull that surrounds & protects the eye
I. EXTERNAL LAYER
- Fibrous coat that supports the eye a. SCLERA - a tough, leather-like tissue, also extends around the eye. Just like an eggshell surrounds an egg and gives an egg its shape, the sclera surrounds the eye and gives the eye its shape.The extraocular muscles attach to the sclera. These muscles pull on the sclera causing the eye to look left or right, up or down, and diagonally. * opaque white tissue normal – white * systemic problems – icteric sclera
b. CORNEA – dense transparent layer. The cornea is the transparent, clear layer at the front and center of the eye. It is well supplied with nerve endings. The main purpose of the cornea is to help focus light as it enters the eye. If one wears contact lenses, the contact lens rests on the cornea. normal – transparent, smooth, shiny & bright accident or eye injury – cloudy areas or specks on the cornea
II. MIDDLE LAYER
- Vascular & heavily pigmented a. CHOROID
- lines most of the sclera & is attached to the retina
- contains many blood vessels
- supplies nutrients to