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How the Eye WorksThe five senses include sight, sound, taste, hearing and touch. Sight, like the other senses is closely related to other parts of our anatomy. The eye is connected to the brain and dependent upon the brain to interpret what we see. How we see depends upon the transfer of light. Light passes through the front of the eye (cornea) to the lens. The cornea and the lens help to focus the light rays onto the back of the eye (retina). The cells in the retina absorb and convert the light to electrochemical impulses which are transferred along the optic nerve and then to the brain. The eye works much the same as a camera. The shutter of a camera can close or open depending upon the amount of light needed to expose the film in the back of the camera. The eye, like the camera shutter, operates in the same way. The iris and the pupil control how much light to let into the back of the eye. When it is very dark, our pupils are very large, letting in more light. The lens of a camera is able to focus on objects far away and up close with the help of mirrors and other mechanical devices. The lens of the eye helps us to focus but sometimes needs some additional help in order to focus clearly. Glasses, contact lenses, and artificial lenses all help us to see more clearly. What is the muscular layer surrounding the pupil?The iris sphincter muscle, also known as the pupillary sphincter or sphincter pupillae, is a muscle located in the colored part of the eye called the iris. The sphincter muscle fibers are located near the pupillary margin and are slightly anterior to the pigmented epithelium of the iris.
What is the muscle that surrounds the eye?The orbicularis oculi muscles are the main protractors (closure) of the eyelids. It is a flat, ringlike band of skeletal muscle surrounding the anterior orbit composed of three parts: the orbital portion, the palpebral portion, and the lacrimal portion.
What part of the eye has color and is a muscle?Iris. This is the colored part of the eye. It contains a ring of muscle fibers that expand or contract the size of the pupil to control the amount of light entering the eye.
Why is the iris muscle Coloured?The function of the iris is to limit the amount of light that passes through the lens to the retina. To make the iris opaque, it is coated with the pigment melanin, in varying degrees for each of us. Melanin makes the eyes dark brown and 10,000 years ago, everyone's eyes were this colour.
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