Duction

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A duction is an eye movement involving only one eye. [1] There are generally six possible movements depending upon the eye's axis of rotation:

Human eye mammalian eye; part of the visual organ of the human body, and move using a system of six muscles

The human eye is an organ which reacts to light and pressure. As a sense organ, the mammalian eye allows vision. Human eyes help to provide a three dimensional, moving image, normally coloured in daylight. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth. The human eye can differentiate between about 10 million colors and is possibly capable of detecting a single photon.

Contents

  1. Abduction refers to the outward movement of an eye.
  2. Adduction refers to the inward movement of an eye
  3. Supraduction / sursumduction / elevation
  4. Infraduction / deosumduction / depression
  5. Incycloduction / intorsion
  6. Excycloduction / extorsion

Forced duction test

The forced duction test is performed in order to determine whether the absence of movement of the eye is due to a neurological disorder or a mechanical restriction. [2]

The anesthetized conjunctiva is grasped with forceps and an attempt is made to move the eyeball in the direction where the movement is restricted. If a mechanical restriction is present, it will not be possible to induce a passive movement of the eyeball. [3]

Notes

  1. Kanski, JJ. Clinical Ophthalmology: A Systematic Approach. Boston:Butterworth-Heinemann;1989.
  2. Forced duction - definition from Biology-Online.org
  3. Kunimoto D, Kanitkar K & Makar M. The Wills Eye Manual. Office and Emergency Room Diagnosis and Treatment of Eye Disease. Fourth Edition. Lippincott Williams & Wilkins; 2004

See also

Extraocular muscles

The extraocular muscles are the six muscles that control movement of the eye and one muscle that controls eyelid elevation. The actions of the six muscles responsible for eye movement depend on the position of the eye at the time of muscle contraction.

Eye examination a series of tests assessing vision and pertaining to the eyes

An eye examination is a series of tests performed by an ophthalmologist, optometrist, or orthoptist, optician (UK), assessing vision and ability to focus on and discern objects, as well as other tests and examinations pertaining to the eyes. Health care professionals often recommend that all people should have periodic and thorough eye examinations as part of routine primary care, especially since many eye diseases are asymptomatic.

Vergence

A vergence is the simultaneous movement of both eyes in opposite directions to obtain or maintain single binocular vision.

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