7 - NEURO-OPHTHALMOLOGY

Abstract

This chapter describes neuro-opthalmology. The visual pathway or the third, fourth, fifth, and sixth cranial nerves are frequently affected by the diseases of the central nervous system. The ophthalmoscopic picture of optic disc swelling shows the blurring of the disc margin and the swelling of the optic nerve head, with filling in of the central physiological cup. The ophthalmoscopic appearance of disc edema in papilledema and papillitis is the same. Papilledema is a passive swelling of the optic disc commonly caused by raised intracranial pressure. Papillitis is an inflammation of the optic nerve, frequently of uncertain etiology. Ischemia to the optic nerve head from arteriolar sclerosis and temporal arteritis also causes sudden visual loss with a swollen optic disc in the elderly population. Pseudo-papilledema is a variation in the appearance of the optic disc, which is sometimes mistaken for true disc edema. Retrobulbar neuritis is an inflammation of the optic nerve with similar symptoms and signs as papillitis except that the optic disc edema is absent. A chiasmal lesion causes a characteristic bitemporal hemianopic field defect. The presence of optic atrophy and poor visual acuity usually indicates that the condition is already at a very advanced stage. A post-chiasmal lesion causes a homonymous hemianopic field defect. It is usually due to either a cerebro-vascular occlusion or a tumor. Nystagmus is an involuntary, oscillatory movement of the eyes.