ORBITAL COMPARTMENT SYNDROME: CHECK FOR AFFERENT PUPILLARY DEFECT

A patient presents in a coma after head and face injury. You note proptosis and the CT shows retroorbital hematoma. You wonder whether you should decompress this. Normally we based decompression on visual acuity but that is not available in the comatose patient. What can we do?

 

Afferent pupillary defect (swinging flashlight test) may be an important finding in these patients. A recent review of 8 cases showed that it was present in 7 of the 8, and was not able to be tested in the 8th.(Sun MT EMA 2014)

 

Other objective findings would include firmness to palpation, which is helpful because when you decompress the eye you want to be able to confirm your procedure was effective. If the tense eye becomes soft, that is helpful. Measure intraocular pressure for an objective measure. Do not press on the eye if open globe is on the differential.

 

Take Home Points:

-Look for afferent pupillary defect in patients suspected of having orbital compartment syndrome

-Palpate the eye before and after decompression

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LID LAG AS A SIGN OF HYPERTHYROIDISM

A patient presents with tachycardia. You notice the eyes seem wide. Is this the lid lag of hyperthryoidism?

The terminology of the opthalmologic signs of hyperthyroidism is sometimes excessively parsed. It is lagophthalmos when the eye does not close, von Grafe’s sign when the act of looking down causes a temporary lid retraction, and lid lag when the lid appears persistently retracted while looking down.(Harvey Opthalm Surg 1981)

It is probably sufficient to use the term lid lag for any of these conditions. The pathophysiology is the opposite of the ptosis of Horner’s syndrome. The sympathetically-innervated Mueller’s muscle has an increase rather than a decrease in the tone. As for its sensitivity and specificity, most studies neglect to record this sign.

We are not discussing here the other opthalmologic findings specific to Grave’s disease, which result from myxedema/swelling.

Take Home Points:

Hyperthyroidism causes increased tone in Mueller’s muscle, which causes lid lag

EYELID EVERSION

There are two situations when we particularly need to open the lid.  The first is to look for a foreign body. The lower fornix is easy to visualize. The upper fornix can not be fully visualized. Double lid eversion is recommended, which basically means taking retractors and flipping the tarsal plate upward. This is done most easily with the patient looking down. A q-tip can be used instead, with fingers holding the lashes. This still does not allow complete visualization, and some recommend sweeping the upper fornix to sample for the foreign body. However, this technique would only work if the foreign body has more avidity for the q-tip than the conjunctivae, which is wishful thinking. If there is doubt, have the patient follow-up with the opthalmologist.

 

The second situation is chemosis or swelling, particularly in trauma. You pull the lids away and edema rolls over the eye. What do you do next?

 

 

Cleaning the skin might allow a better grip. The ideal method is the Desmarre eyelid retractor, but it is rarely found in the ED. It is a metal non-sharp hook that pulls the entire lid away.  They can be made by bending the curved end of a paper clip to about 90-180 degrees.  Just make sure it is not one of those flaking paperclips that could leave a foreign body in the eye. This should allow you to at least examine acuity, pupils, and the anterior chamber.

 

Take Home Points:

Clean the eyelid grease for a better grip

Use a Desmarre retractor or modified paperclip if necessary,

 

TROUBLESHOOTING VISUAL ACUITY

Do your nurses have trouble getting visual acuity in triage? It is a common problem in emergency medicine practice, but fortunately there are solutions.

 

1. Patient can not open eye

Many patients say they can’t open the eye. By holding the lid open, usually the patient is able to demonstrate normal acuity. Topical anesthesia can improve compliance by alleviating pain. Clean around the eye if the finger slips because the skin is too greasy.

 

2. Patient forgot to bring glasses

There are two solutions:

 

a. Pinhole correction

Pinhole correction allows only parallel light to pass, giving a more accurate estimate of visual acuity in such patients. However, I find that this technique does not always get us back to normal vision.

 

b. Near-Snellen card

Technically this is called a Rosenbaum card but most non-ophthalmologists do not use the eponym.  This is widely available in pocket resources, on the internet, and with smartphone applications. It bypasses the need for corrective lenses in myopic patients.

 

Take Home Points

-If the patient won’t open the eye, assist him or her

-Pinhole correction can partially correct for refractive error

-Near Snellen testing can be an acceptable alternative for those who forget their glasses

OCULAR PALPATION

A patient presents with eye pain and redness. Does palpation help raise or lower the probability of acute glaucoma?  Is this physical examination finding worth pursuing?

First, it should be stated that many physical findings we pursue lack sufficient specificity to rule in a diagnosis.  Others lack the sensitivity to rule it out.  Palpation of globe pressure has not been studied prospectively as a physical finding in the acute painful eye population.

However, many opthalmologists consider it a useful finding.  If one palpates an asymmetrically rock hard globe on one side then the differential diagnosis can be narrowed substantially.  All that is required is confirmation through tonometry.

It is reasonable for emergency physicians to cultivate this as a bedside skill.  Have the patient look down, and palpate the superior portion of the globe through a closed lid.  See how much force is required to indent the wall. (Heidary 2010).  Use tonometry as the gold standard and hone your skills.

Update: Since first writing this post I heard from a colleague who had a severe trauma patient with GCS 3 and proptosis. Ocular palpation led her to the diagnosis of orbital compartment syndrome. During lateral canthotomy she had trouble with the inferior cantholysis, and again it was the palpation that led her to keep going until the eye softened and she was assured of successful release of pressure.