Understand Extraocular Muscles And How They Change The Shape Of The Eye

acaihw — Sat, 02 Jan 2010 09:56:53 +0000

It is important to understand how the Extraocular muscles change the shape of the eye. The eye is like a balloon. The Extra ocular muscles can hold tension, thus causing a distortion in the shape of the eye. In the normally shaped eye the light that enters the eye focuses on the retina. When the eye is too long for the focusing mechanism, the light focuses in front of the retina. This is nearsightedness or myopia.

When the eye is too short for the power of the focusing mechanism of the eye, the light focuses behind the retina. This is called farsightedness or hyperopia. When there is a greater curvature of the cornea, or the lens, or the back of the eye in one direction more than the other, this is called astigmatism. In each of these cases, vision can be corrected through LASIK eye surgery.

The oblique muscles wrap around the center of the eye. The superior comes from above and the inferior oblique from below. The superior oblique comes from the back of the orbit behind the eye, angles forward through a pulley at the medial superior bony orbital ridge by-way of a tendon which passes through the trochlea (pulley), and then traverses laterally over the top of the eye. Thus this muscle and its tendon may cause a distortion from two different directions, one coming straight from the back forward, and the other around the equator of the eye after it passes through the trochlea.

The inferior oblique muscle attaches to the orbital bone at the inferior nasal bone about 45 degrees below a horizontal line through the center of the eye. This muscle then passes under the eye and attaches laterally posterior to the equator of the eye.

If the superior and /or the inferior muscles were to contract at the same time, this would act as if a string were contracting around the middle of a Balloon and would elongate the eye. Thus the eye would be nearsighted.

If the rectus muscles which originate immediately behind the superior, inferior, medial, and lateral were to contact at the same time the back of the eye would move forward. This also may be due to the fat and the blood vessels behind the eye in the middle of the rectus muscles which are being squeezed forward like a tube of toothpaste. Astigmatism may be caused by one or more muscles exerting pressure from one or more directions. This may be due to more electrical tension being fired at a constant higher baseline tension in one or more muscles.

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Understand Extraocular Muscles And How They Change The Shape Of The Eye