The Accessory Optic System

Abstract

The accessory optic system (AOS) provides a critical piece of the puzzle in infantile strabismus by explaining how visual motion can be processed in a vestibular coordinate system. This subcortical existence explains how torsional eye movements can be generated in response to unequal binocular visual input, and how individual extraocular muscles can be driven to overact when binocular visual development is comprised. The clear implication is that this atavistic system somehow remains functional in infantile strabismus and infantile nystagmus. This proposition is not so bold when one considers that our extraocular muscles are oriented in a semicircular canal-based planar coordinate system. The AOS subserves optokinesis, however, so it remains unclear whether primitive luminance pathways are encoded in a similar coordinate system, or whether luminance disparity generates correlative input the AOS.