Acquired Optic Nerve Diseases

This chapter focuses on the most frequently acquired optic nerve diseases: their signs and symptoms, visual field findings, and the required basic workup and management. Acquired optic nerve diseases are often vision threatening and sometimes even life threatening. There is a need for accurate and timely diagnosis. Therefore, it is incumbent on the clinician to identify optic neuropathies, separate them from chronic congenital and hereditary problems, and aggressively pursue the diagnosis and treatment as necessary. In the workup of optic neuropathies, the visual field is extremely helpful. All patients with suspected optic neuropathies require careful examination of the visual fields for detection, characterization, and monitoring. Acquired optic neuropathies include inflammatory, ischemic, compressive, metabolic, and central nervous system–reflected pathology (papilledema). Inflammatory optic neuropathies include optic neuritis and its various etiologies such as demyelination, infective, immune-mediated (atypical), and slowly progressive/ chronic. Ischemic optic neuropathies include nonarteritic ischemic optic neuropathy (NAION) and arteritic ischemic optic neuropathy (AAION). Metabolic optic neuropathies include nutritional and/or toxic etiologies. Compressive optic neuropathies can occur due to mass effect on the disc optic, gliomas, and perioptic meningiomas. Papilledema may be primary (pseudotumor cerebri) or secondary to central nervous system mass effect. Optic neuritis is defined as a primary inflammation of the optic nerve. It is characterized by central visual loss that worsens over days and usually peaks about 1 to 2 weeks after the onset. It is usually unilateral but may be bilateral, especially in children, following viral infections like measles, mumps, and chickenpox. It occurs most commonly in adults (18-45 years old). Orbital or periocular pain may be present or precede the visual loss and is exacerbated with eye movements. Etiologies include demyelinating diseases/multiple sclerosis;, idiopathic, viral, or bacterial infections (syphilis); contiguous inflammation of the meninges, orbit, or sinuses,; granulomatous inflammation (tuberculosis, sarcoidosis, and cryptococosis); and autoimmune diseases. It is the most common cause of acute visual loss from optic nerve disease in the young and middle-aged adult group.