The eye motility system is highly coordinated and closely connected with different brain structures. Even the slightest imperfections lead to subjective and objective disturbances. The proper function of the retina, optic nerve, pupils, and ocular motor system provides valuable information about the integrity of neural pathways from the cerebral cortex through the brainstem to the cerebellum. For that reason, eye motility disorders often serve as the initial clinical sign of life-threatening or debilitating systemic conditions. Because these pathways are highly sensitive to metabolic, immunologic, infectious, and neoplastic disruptions, a precise neuro-ophthalmic evaluation can lead to the early diagnosis of underlying systemic pathology before systemic symptoms manifest. This book reminds readers that careful observation of the eyes is far more than a routine examination. Some of the most urgent signs of ocular motility disorders are: diplopia, nystagmus, paresis and paralysis of the oculomotor nerves, oscillopsia, restrictive ophthalmoplegia, and opsoclonus-myoclonus. Recognizing some of these signs can allow the diagnosis at an earlier, more treatable stage. The authors hope that this book will serve as a bridge between ophthalmologists, neurologists, infectious disease specialists, endocrinologists, and physicians from other medical disciplines. Our goal is to increase awareness of ocular motility disorders and to encourage a multidisciplinary approach to their diagnosis and management.