eMedicine Specialties > Ophthalmology > Orbit
Exophthalmos: Differential Diagnoses & Workup
Updated: Feb 7, 2007
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Differential Diagnoses
Other Problems to Be Considered
Pseudoproptosis can manifest itself in many ways. If the contralateral orbit is enophthalmic, then the ipsilateral side will be viewed erroneously as being proptotic. If there is contralateral blepharoptosis, there can be the appearance of ipsilateral proptosis. Axial myopia or buphthalmos can mimic proptosis as can asymmetrical bones of the orbital rims or midface. Pseudoproptosis also can be simulated by upper eyelid or lower eyelid retraction. The resultant scleral show creates the impression of the globe protruding forward. In patients with contralateral enophthalmos, the normal orbit, which is situated more anteriorly, may simulate proptosis when there is none.
Workup
Laboratory Studies
- Patients with thyroidopathy should undergo the appropriate thyroid function studies, even though some patients are euthyroid at the time of presentation with exophthalmos. Approximately 80% of those with Graves disease manifest orbital signs within 18 months, supporting the need for ophthalmic evaluation.
- Any patient suspected of having a neoplasm as the cause of the proptosis should undergo imaging studies (see Imaging Studies). The imaging results should direct further laboratory studies. For example, in a patient with proptosis due to lymphoma, hematologic studies, further body imaging, and a bone marrow biopsy may be indicated.
- In patients with proptosis due to orbital cellulitis, complete blood counts, blood and nasal cultures, and sinus imaging studies may be warranted.
Imaging Studies
- CT scan, first used in the 1970s, is the product of tissue density calculations. X-rays with different vectors are emitted, penetrating through target tissues with resulting radioabsorbencies. These differences in radioabsorbencies are assigned value-specific gray shades to create the 2-dimensional image. CT scan can produce detailed axial and coronal views of soft tissue and bony structures. Image windows from 1.0-3.0 mm in thickness allow for detailed evaluation of orbital masses. Contrast-enhanced images may be obtained and can help in identifying inflammatory processes, vascular tumors, and engorged vessels. Calcified lesions are discernible without the addition of contrast.
- Magnetic resonance imaging (MRI) excites protons by applying a radio frequency with a strong magnetic field. Hydrogen nuclei emit signal intensities that are assigned specific gray tones to create an anatomical reproduction. Three-dimensional views can be gained directly, in any anatomical plane, offering excellent spatial resolution of orbital masses and soft-tissue enhancement. MRI may provide excellent soft-tissue resolution, but CT scan is superior for gleaning details about orbital bony structures.
- Ocular ultrasonography can be used to visualize anterior and middle orbital lesions. Sound waves of 5-15 MHz breech orbital tissues that reflect echogenic energy captured by an oscilloscope. A-scan ultrasonography allows for a 1-dimensional description of echoes, while B-scan ultrasonography provides a 2-dimensional image. C-scan ultrasonography affords coronal views, and D-scan ultrasonography creates 3-dimensional orbital views. With the advent of CT scan, C- and D-scan ultrasonography remains unpopular. Doppler ultrasonography may be used to evaluate orbital vasculature and blood flow.
More on Exophthalmos |
| Overview: Exophthalmos |
 Differential Diagnoses & Workup: Exophthalmos |
| Treatment & Medication: Exophthalmos |
| Follow-up: Exophthalmos |
| Multimedia: Exophthalmos |
| References |
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References
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Further Reading
Keywords
proptosis, exorbitism, eyeball protrusion, thyroid orbitopathy
