--to see nerve damage to the optic nerve disc (head) on a good opthamologic exam, though the optic nerve is actually myelinated with the same myelin as the spinal cord, and therefore usually considered part of the central nervous system rather than the peripheral one, and certainly not a small fiber type nerve.

Generally when such damage is seen, it involves a "washing out" or "pale" optic nerve appearance, which generally means damage to the myelin, though there can be axonal damage as well.

Less profound optic nerve damage may be asymptomatic, but if it is extensive usually there are associated visual disturbances. The most common types of optic neuropathy/paleness in the Western world, especially among older people, are associated with diabetes, in which the mechanism is primarily ischemic/circulatory, and glaucoma, in which the mechanism is primarily compressive due to fluid build up. But potential causes are as wide ranging as the causes of other neuropathies. In particular, in younger patients, autoimmune, toxic, and nutritional deficiencies should be investigated.