the underlying malignancy.
Evaluation of cases of suspected infiltrative optic neuropathy should include an MRI of the brain and orbits with fat suppression and use of gadolinium contrast to rule out compressive lesions and to confirm pachymeningeal or meningeal infiltration. The MRI scan may show diffuse thickening and enhancement of the dura and the surrounding subarachnoid space in affected regions, including the optic nerve sheaths; however, abnormalities may not be visible in the early stages. Serologic testing includes screening tests for the myeloproliferative, inflammatory, and infectious disorders noted earlier. Finally, CSF analysis may reveal malignant cells, elevated white blood cell count, and elevated protein level consistent with a neoplastic, infectious, or inflammatory cause. The sensitivity of a single lumbar puncture is low, and repeat testing is often necessary. Timely, correct diagnosis is essential for the following reasons:
Identification of the associated malignancy or systemic disease may be life-saving.
In malignancies, palliative radiation therapy may substantially improve vision, even though the long-term prognosis is poor. Median survival for meningeal carcinomatosis ranges from 4–9 weeks, even with aggressive therapy; only a few patients survive past 1 year.
In infectious or inflammatory disorders, antimicrobial or corticosteroid therapy may partially reverse damage resulting from infiltration and stabilize the systemic condition.
de Fatima Soares M, Braga FT, da Rocha AJ, Lederman HM. Optic nerve infiltration by acute lymphoblastic leukemia: MRI contribution. Pediatr Radiol. 2005;35(8):799–802. Epub 2005 Apr 7.
Millar MJ, Tumuluri K, Murali R, Ng T, Beaumont P, Maloof A. Bilateral primary optic nerve lymphoma. Ophthal Plast Reconstr Surg. 2008;24(1):71–73.
Yeung SN, Paton KE, Dorovini-Zis K, Chew JB, White VA. Histopathologic features of multiple myeloma involving the optic nerves. J Neuroophthalmol. 2008;28(1):12–16.
Optic Atrophy
The combination of vision loss, an RAPD, and optic atrophy is nonspecific and might represent the chronic phase of any of the optic neuropathies described earlier. When historical features and clinical signs do not suggest a specific cause, baseline studies of optic nerve function and a screening workup for treatable causes are usually undertaken. The level of optic nerve function is established by visual acuity determination, color vision testing, and quantitative perimetry testing. The degree and pattern of atrophy are documented by fundus photography, preferably in stereoscopic views, to detect subtle changes in contour over time. Retinal nerve fiber layer thickness can be monitored using optical coherence tomography.
Neuroimaging, preferably MRI of the brain and orbits with use of gadolinium contrast and fat suppression, is warranted in any case without a clear cause. In a study of 98 adult patients with isolated optic atrophy, 20% harbored compressive lesions. There was low yield in screening for syphilis, vitamin B12 deficiency, folate deficiency, vasculitis, sarcoidosis, and heavy metal toxicity for patients without a history or examination suggestive of these specific diseases. In the appropriate clinical or historical setting, the clinician should pursue laboratory evaluation. Observation remains reasonable for patients with negative results from testing. However, if the condition worsens or new findings develop, reassessment of the initial testing or additional testing becomes necessary.
Lee AG, Chau FY, Golnik KC, Kardon RH, Wall M. The diagnostic yield of the evaluation for isolated unexplained optic atrophy. Ophthalmology. 2005;112(5):757–759.