Beyond the cover test: the motor half of the sensorimotor exam

The cover tests fulfill both the "sensory" and the "motor" requirements of the sensorimotor exam because they not only detect and quantify strabismus but also evaluate control. Control is achieved through various types of vergence, but vergence is not the only type of eye movement that is integral to fusion. The function of all eye movements is to position and maintain similar images on corresponding areas of the retinae in order to sustain binocular vision. Therefore, a complete motor exam should include evaluation of all eye movement systems. Such an exam can be performed without expensive and complicated equipment, without supplementary education, without significantly extending exam time, and within the confines of an average exam lane, because much of the exam is concealed within the standard sensorimotor evaluation. The term "sensorimotor exam" underscores the fact that sensory and motor fusion, and their respective cortical pathways, are inextricably linked, and function simultaneously and cooperatively to achieve normal visual experience.