On visual field examination, the phenomenon of preserved function of the central visual field in the partially and totally blind visual field is called “macular avoidance”. This phenomenon occurs when there is damage or lesions in the posterior and middle visual radiations or in the visual cortex. There are the following explanations for the mechanism of macular avoidance: (1) The macular area is innervated by both sides of the cerebral cortex, and there are fibers in the caudal part of the corpus callosum to the ventral part of both sides of the visual radiation fibers, which may be the link between the two sides of the macular bundle, this is the more popular explanation. (2) Since macular fibers are widely distributed in occipital cortex, it is usually difficult for a lesion to completely destroy the distributed area, so it may present macular evasion phenomenon. (3) Since the macular fibers are finally located in the occipital cortex, there is blood supply from 2-3 blood sources in this part, and the function of macular fibers is not impaired when only one blood source is blocked by the lesion.