The orbit examination is one of the most difficult to perform under examination conditions. A large number of potential manoeuvres and measurements need to be performed. It is important that the examiner be comprehensive and systematic, yet flexible enough to tailor their exam to the patient being examined. Avoid verbalising a long list of negatives (e.g. “there is no hypertelorism”) that will be of little interest to an examiner. Most orbital patients will either have inflammation (most commonly thyroid orbitopathy) or an orbital tumour (including vascular, cystic and neoplastic lesions). Primary objectives of the orbit examination include establishing a differential diagnosis, assessing optic nerve integrity and documenting baseline findings for later comparison.
The worse eye is usually the affected one (may be amblyopic).
If the patient wears spectacles, remove these prior to further inspection / palpation. Look at the whole patient for clues (e.g. syndromes).
Hertel exophthalmometry measures the distance between the lateral orbital rim and the corneal apex. Proptosis of greater than 22mm or an asymmetry of greater than 2mm between is significant. Note the distance between the lateral orbital rims to allow subsequent measurements to be comparable.
Tell the patient that “I am going to place this (exophthalmometer) on the corner of your eyes”. Feeling for the lateral orbital rims before positioning the exophthalmometer prevents startling the patient or causing them pain (a certain fail in exams). This also allows for palpation in case of lateral wall orbital decompression in thyroid orbitopathy. Widen the exophthalmometer until it just rests on the lateral orbital rims. Close your right eye and position this in front of the patient’s right eye. Tell the patient to “look at my closed eye”. Using your left eye, adjust your head position so that the line on the exophthalmometer is appropriately centered (to eliminate parallax error). Read off the position of the corneal apex on the graticule. Repeat for the patient’s left eye by positioning your closed left eye in front of it and reading the measurement with your right eye.
Under the time pressure of exam conditions there is often insufficient time to measure dystopia, but if this is requested the following process should be followed. Place a horizontal ruler centred on the nose, passing in front of the lateral canthi. Measure the horizontal distance between the midline and the corneal reflex and the vertical displacement from this plane.
Warn the patient that “I am going to feel around your eyes. Please close your eyes”.
This is the most important parameter measured in an orbital exam. Ensure you do not run out of time to check these.
Under exam conditions there is rarely sufficient time to perform cover testing. Proceed to examining ocular rotations with an “H” pattern. With the eyes straight, check upgaze then downgaze, making note of the presence / absence of “lid lag” (the upper lid lagging behind the speed of the depression of the globe, as seen in thyroid orbitopathy)
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