The Near Response: Modeling, Instrumentation, and Clinical Applications

The complex task of focusing, verging of the two eyes, and constriction of the pupil is accomplished by a network of oculomotor systems. The accommodation system senses blur of the retinal image and controls the lens curvature to keep the image of the target in focus. The vergence system detects disparity between the retinal images in the two eyes and controls the rotation of the two eyes to bring about a single visual percept. The pupillary system works in conjunction with the accommodation and vergence systems, but is essentially open loop. This review will cite some of the important bioengineering contributions in modeling, instrumentation, and clinical applications to each of the above oculomotor systems over the past 25 years. These major innovations have helped to provide a better means of measuring the oculomotor responses and have improved our understanding of these systems in isolation as wel as their mutual interactions. This further clarified our understanding of defects in a system that led to clinical abnormalities. The continued advances offered by bioengineering will aid further in our understanding of oculomotor deficits and their treatment.