Hess

Hess is a medical term referring to the Hess screen test, a diagnostic procedure used to evaluate the function of the extraocular muscles which control the movement of the eye. The test is named after Walter Rudolf Hess, a Swiss physiologist who won the Nobel Prize in Physiology or Medicine in 1949.

Overview

The Hess screen test is a binocular test performed to evaluate the strength and balance of the extraocular muscles. The test is performed using a specially designed screen and a pair of red-green glasses. The patient is asked to fixate on a target on the screen while the examiner moves a second target around the screen. The patient's task is to keep the two targets aligned. Any misalignment of the targets indicates a weakness or imbalance in the extraocular muscles.

Procedure

The Hess screen test is performed in a dark room. The patient is seated at a distance of 1 meter from the screen. The patient wears red-green glasses, with the red lens over the right eye and the green lens over the left eye. The examiner moves a red light around the screen, and the patient is asked to keep a green light aligned with the red light. The patient's responses are recorded on a chart, which provides a visual representation of the function of the extraocular muscles.

Interpretation

The results of the Hess screen test can help diagnose various conditions that affect the function of the extraocular muscles. These conditions include strabismus, myasthenia gravis, and thyroid eye disease. In strabismus, the eyes are not properly aligned with each other, which can cause double vision. Myasthenia gravis is a neuromuscular disorder that causes weakness in the skeletal muscles, including the extraocular muscles. Thyroid eye disease is an autoimmune condition that affects the muscles and tissues around the eyes.

See also

• Walter Rudolf Hess
• Extraocular muscles
• Strabismus
• Myasthenia gravis
• Thyroid eye disease

References

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