Neuro-ophthalmology is the subspecialty of both neurology and ophthalmology concerning visual problems that are related to the nervous system. A neuro-ophthalmologist is a neurologist or neurosurgeon or ophthalmologist specializing in diseases affecting vision that originate from the nervous system. Some commonly seen diseases that a neuro-ophthalmologist may treat include optic neuritis, optic neuropathy, optic disc edema, ocular myasthenia gravis, brain tumours or stroke affecting vision, idiopathic intracranial hypertension or pseudotumor cerebri, unexplained visual loss, headaches and double vision. Neuro-ophthalmologists are medical doctors who initially specialize in either neurology or ophthalmology, then do subspecialty training, through fellowships, in the complementary field.