Sadun Alfredo A, Wang Michelle Y
Departments of Ophthalmology and Neurosurgery, Doheny Eye Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA.
Handb Clin Neurol. 2011;102:117-57. doi: 10.1016/B978-0-444-52903-9.00011-X.
The optic disc represents the anterior end of the optic nerve, the most forward extension of the central nervous system (CNS). The optic disc gives a rare glimpse into the CNS. Hence, diseases of the CNS are often manifested on fundus examination. Abnormalities of the optic disc may reflect eye disease (such as glaucoma), problems in development (as in various syndromes), or CNS disease (such as increased intracranial pressure). Each optic nerve is composed of about 1.2 million axons deriving from the retinal ganglion cells of one eye. Optic atrophy is a morphological sequela reflecting the loss of many or all of these axons. Myriad diseases such as hereditary, metabolic, tumor, and increased intracranial pressure can lead to optic atrophy. Some diseases, such as optic disc drusen, intracranial masses, orbital tumors, ischemic optic neuropathies, inflammations, and infiltrations, can produce optic disc edema before leading to optic atrophy. A number of new imaging modalities, such as optical coherence tomography (OCT), quantitate the thickness of the peripapillary retinal nerve fiber layer as an indirect measure of axonal loss or swelling. OCT can therefore be used to quantitate pathology or the response to therapy in various generalized CNS conditions, such as multiple sclerosis.
视盘代表视神经的前端，是中枢神经系统（CNS）最靠前的延伸部分。视盘为观察中枢神经系统提供了难得的窗口。因此，中枢神经系统疾病常在眼底检查时表现出来。视盘异常可能反映眼部疾病（如青光眼）、发育问题（如各种综合征）或中枢神经系统疾病（如颅内压升高）。每条视神经由来自一只眼睛视网膜神经节细胞的约120万个轴突组成。视神经萎缩是一种形态学后遗症，反映了许多或所有这些轴突的丧失。多种疾病，如遗传性、代谢性、肿瘤性和颅内压升高，均可导致视神经萎缩。一些疾病，如视盘玻璃膜疣、颅内肿块、眼眶肿瘤、缺血性视神经病变、炎症和浸润，可在导致视神经萎缩之前引起视盘水肿。一些新的成像方式，如光学相干断层扫描（OCT），可定量测量视乳头周围视网膜神经纤维层的厚度，作为轴突损失或肿胀的间接指标。因此，OCT可用于量化各种全身性中枢神经系统疾病（如多发性硬化症）的病理情况或对治疗的反应。
