The most common tumors of the optic nerve include gliomas and meningiomas, according to Patient.co.uk. Both conditions are associated with a gradual, painless fogginess and dimming eyesight. Another usually benign tumor is the melanocytoma, which grows very slowly. Symptoms of melanocytoma are caused by expansion of the tumor and subsequent pressure on adjacent structures rather than malignant growth. Other brain tumors can also affect the optic nerve indirectly by compression.
Patients with optic nerve glioma often have hormone problems because these tumors are located at the base of the brain, which is where hormones are regulated, according to Johns Hopkins University. Gliomas are difficult to treat because of the delicacy of the surrounding brain tissue. Gliomas are classified according to their stage of development (grades I through IV, with I being the most treatable) as well as the type of cells they affect. Meningiomas are the most common type of tumor, comprising about 30 percent of tumor incidence in adults. They form in the meninges, which form the outer covering of the brain just beneath the skull. In most cases, meningiomas are benign. Meningiomas occur most frequently in patients in their 70s and 80s. They can be removed surgically, but there is a chance that they return as malignant tumors, according to Johns Hopkins University.