Primary Tumours of The Optic Disc and The Optic Disc Sheath

Abstract

Primary optic nerve and optic nerve sheath tumors constitute approximately 8% of intraorbital tumors and although most of them are benign, they are manifested by findings that significantly affect visual function such as vision loss, visual field defect and proptosis. Tumors originating from the optic nerve trunk are mostly benign optic nerve glioma, but rarer tumors such as ganglioglioma, medulloepithelioma, hemangioblastoma, melanocytoma and high-grade glioblastomas such as malignant optic nerve glioma can also be detected. Tumors originating from the optic nerve sheath usually have optic nerve sheath meningioma (ONSM), of those with intraorbital and intracanalicular origin are classified as primary and intracranial ONSMs are classified as secondary tumors. Optic glioma, ONSM, and hemangioblastomas can be seen sporadically or as a component of Type 1 and Type 2 Neurofibromatosis (NF) and Von Hippel-Lindau (VHL) syndromes, respectively. Treatment with systemic chemotherapy, surgical resection and radiotherapy methods should be considered when progressive vision loss, visual field defect and cosmetically intolerable proptosis develop in optic nerve and nerve sheath tumors, which can have a quiet course for years in terms of visual function. While systemic chemotherapy is accepted as the main treatment method in optic gliomas, more successful results are obtained with specialized treatment methods such as stereotactic fractionated radiotherapy in ONSMs.