Tumors of the Optic Nerve
Primary tumors of the optic nerve include anterior visual pathway gliomas and optic nerve sheath meningiomas. Both are relatively rare lesions that result in significant visual morbidity. Together they account for less than 4% of all orbital tumors. There
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Jonathan J. Dutton
Introduction Primary tumors of the optic nerve include anterior visual pathway gliomas and optic nerve sheath meningiomas. Both are relatively rare lesions that result in significant visual morbidity. Together they account for less than 4% of all orbital tumors. There has been controversy about the natural history and appropriate management of these lesions, often resulting from small sample sizes and short follow-up periods. Other tumors, such as gangliogliomas and primary lymphomas, have also been described but are extremely rare (Table 11.1).
Anterior Visual Pathway Glioma Optic pathway gliomas (OPG) are uncommon benign lesions classified as pilocytic astrocytomas. They represent 1.5–4% of all orbital tumors and 50–55% of all primary optic nerve tumors [1, 2].
Association with Neurofibromatosis Type 1 Optic pathway gliomas may be sporadic or syndromic, the latter mostly associated with neurofibromatosis type 1 (NF1). The reported incidence of NF1 among patients with optic gliomas varies from 10% to 70%, with an overall incidence of 29% [1]. Although some reports have shown no difference in the course and prognosis of optic pathway gliomas with and without NF1, others have shown a more indolent course and a better visual prognosis in patients with OPG and NF1 [3–5]. When associated with NF1, the glioma may present at a somewhat later age and show progression for a long time, justifying regular ophthalmological monitoring of this population over a long period [6, 7]. OPG occur in 15–20% of children with NF1, even though visual symptoms are seen in less than half of these individuals. Reliable visual evaluation can be challenging in young children making it difficult to determine if, and when, intervention is warranted. A combination of ophthalmic, electrophysiologic, and imaging biomarkers has been proposed as a guideline for initiating therapy [8].
J. J. Dutton (*) Department of Ophthalmology, University of North Carolina, Chapel Hill, NC, USA e-mail: [email protected] © Springer Nature Switzerland AG 2019 C. J. Hwang et al. (eds.), Clinical Ophthalmic Oncology, https://doi.org/10.1007/978-3-030-13558-4_11
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Table 11.1 Diagnostic features of optic nerve tumors Lesion Optic nerve glioma
Mean age 8.8 years
Sex F = M
Location ON, OC, MB
Malignant optic glioma
42.5 years
65% M
OC +/− ON
Optic sheath meningioma
41 years
60% F
ON
Prognosis Vision = fair to good Life = 36% mortality Vision = blindness Life = 100% mortality Vision = poor Life = 0% mortality
ON optic nerve, OC optic chiasm, MB midbrain
Clinical Features Age Distribution Gliomas have been described in patients from birth to 79 years of age. However, 71% of cases occur in children in the first decade of life and 90% within the first two decades. The overall mean age at presentation is 8.8 years for all optic gliomas [1]. Sex Distribution The sexual distribution for all optic pathway gliomas shows approximately equal numbers of males and females [1]. For gliomas confined to the o
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