Compressive Optic Neuropathy Workup
- Author: Jonathan W Kim, MD; Chief Editor: Hampton Roy Sr, MD more...
Laboratory Studies
- Blood tests are sometimes helpful in the diagnosis of compressive optic neuropathy. However, the serologic workup should be guided by the history and clinical presentation.[6]
- If thyroid ophthalmopathy is suspected, blood tests for thyroid function and anti-thyroid antibodies should be performed.
- An elevated angiotensin-converting enzyme may be seen in sarcoidosis.
- An elevated prostate specific antigen (PSA) may be helpful in male patients with suspected bony orbital metastases and optic nerve compression.
Imaging Studies
Whenever there is clinical suspicion of compressive optic neuropathy (CON), a neuroimaging study is mandatory to determine the presence and location of the responsible lesion. With the sensitivity and specificity of modern neuroimaging, a negative scan essentially rules out the possibility of CON as the cause of vision loss.
In most cases of CON, magnetic resonance imaging (MRI) is the imaging modality of choice because of the excellent soft-tissue resolution of the anterior visual pathway and parasellar area; typically an orbit and brain MRI with and without contrast is ordered to evaluate a patient for CON.
MRIs are shown below.
Axial MRI taken 3 weeks after the onset of distorted vision in the right eye; visual acuity is reduced to counting fingers at 1 ft. Evidence of optic nerve compression is not seen; disease in the sphenoid sinus is reported. 
MRI of same patient as in the image above taken 4 months later. Patient responded well to IV Solu-Medrol, but symptoms returned when steroids were reduced. Large mass compressing the right optic nerve is seen. Biopsy revealed lymphoma. 
Neuroimaging study (MRI of brain and orbits) revealed an extensive meningioma involving the left orbital apex (arrow). Computed tomography (CT) scanning offers excellent visualization of the bony anatomy and is particularly useful to evaluate the intraconal space of the orbit. However, for imaging the orbital apex and optic canal, MRI is preferred over CT due to the absence of signal interference from adjacent bone seen on tomography.
Ultrasonography may be useful to document the presence of anterior orbital lesions but offers limited penetration into the deep orbit. However, in certain clinical situations, ultrasonography may be used to image patients quickly in the office in order to determine whether CT or MRI is warranted.
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