Chapter 13 Acquired Ocular Motility Disorders and Nystagmus

Abstract

Publisher Summary This chapter discusses acquired ocular motility disorders and nystagmus. Eye movement disorders may be considered in two categories: those that cause incomplete eye movements (ophthalmoparesis) and those that cause excessive eye movements (saccadic intrusions and nystagmus). Central to an understanding and correct diagnosis of abnormal eye movements is the evaluation of ocular alignment, ocular motility, and each functional class of eye movements: optokinetic, vestibular, vergence, smooth pursuit, and saccades. Ophthalmoparesis is caused by the dysfunction of extraocular muscles, the neuromuscular junction, cranial nerves, cranial nerve nuclei, and internuclear and supranuclear connections. The initial pathologic eye movement in nystagmus is a slow drift of the eye away from the desired position, whereas the initial pathologic eye movement in saccadic intrusions is an inappropriate saccade that intrudes on fixation. The identification of the characteristics of nystagmus (physiologic versus pathologic and jerk versus pendular) is necessary for diagnostic evaluation and treatment.