USMLE Internal Medicine Review 11 10 Eye Signs

USMLE Internal Medicine Review 11 10 Eye Signs

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Let’s start our USMLE Review with Hypothyroidism and Hyperthyroidism from the Gold Standard USMLE Foundations of Medicine Audio Review program.


Play USMLE Audio MP3 11 10 Eye Signs Below


Begin 11 10 Eye Signs Transcription

We’ll consider separately now the eye signs associated with Graves’ disease. The American Thyroid Association has a classification system useful in detailing the extent of eye involvement. The classes are numbered from 0-6, from least to most serious eye changes. The first letter of each sign or symptom spells out the pneumonic NO SPECS. Please pause the tape and take a guess at the signs in order. Don’t worry we’ll then go back and detail them. Class 0-N for no signs or symptoms. Class 1-O for only signs, no symptoms. Class 2-S for soft tissue signs and symptoms. Class 3- P for proptosis. Class 4-E for extraocular muscle involvement. Class 5-C for corneal involvement. And class 6-S for site loss.

Is this classification system also useful in accessing the progress of Graves’ disease, why or why not?

  • It’s not useful in accessing the progress of Graves’ disease because one class does not necessarily progress to the next.

In the American Thyroid Association classification of the involvement of Graves’ disease, what is the primary sign which can be observed in Class 1?

  • Class 1 involves spasm of the upper lids which is associated with active thyrotoxicosis. The spasm normally resolves spontaneously when thyrotoxicosis is adequately controlled. Classes 2-6 involve true infiltrative disease of the orbital muscles and tissues. Class 2 is characterized by soft tissue involvement with any or all of these three associated conditions.

First, edema in what location?

  • Periorbital edema.

Second is conjuntival redness or congestion.

And third is conjunctival swelling. What is the term for this?

  • Chemosis.

Class 3 consists of proptosis as measured with which instrument?

  • Proptosis is measured with the hertel exophthalmometer.

This instrument measures the distance which two eye structures?

  • The Hertel Exophthalmometer measures the distance from the orbital ridge to the anterior cornea.

What are typical distances in millimeters between these structures associated with Oriental, Caucasian, and African-American races in that order?

  • Oriental-18, Caucasian-20, and African-American-22 mm.

And what is the extraocular muscle most commonly involved in Class IV Graves’ disease?

  • Class IV most commonly involves the inferior rectus muscle.

Which eye function is limited by problems with the inferior rectus muscle?

  • Limited upward gaze.

And which muscle is next most commonly implicated and which eye function is affected?

  • The medial rectus impairing lateral gaze.

What is the function associated with the corneal involvement of Class V?

  • Keratitis

And Class VI involves site loss due to impairment of which nerve?

  • Optic nerve impairment.



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