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The retinas and anterior visual pathways (optic nerves, optic chiasm, and optic tracts) (Figures 14–1 and 14–2) are an integral part of the brain, providing a substantial proportion of its total sensory input. The pattern of visual field loss indicates the site of damage in the visual pathway (Figures 14–3 to 14–5). Eye movement disorders may be due to disease of cranial nerves III, IV, or VI, or a more central lesion. Cranial nerves V and VII are also intimately associated with ocular function.
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A wide variety of diseases affect the optic nerve (Table 14–1). Clinical features indicative of optic nerve disease are reduction of visual acuity and field, afferent pupillary defect, poor color vision, and optic disk changes.
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