Moving muscles with microchips, mathematics and models: an update on the ‘reverse’ model

This paper reviews the current status of our computer model for the management of strabismus and its future direction. Vector analysis was first used in the 1950s for the assessment of strabismus. Robinson's model' was the first computer simulation of ocular motility. Using physiological principles and anatomical approximations, Robinson's model sought to predict the strabismic pattern to be expected from a given injury. The Kault/Stark 'reverse' model works in the opposite direction, to first simulate the given strabismic pattern and then advise the surgery required to restore orthophoria. The surgeon is able to 'trial' various operations and compare the expected postoperative results. An automated system is currently being developed to ease the difficulty in measuring the position of the eyes in all nine positions of gaze. This paper includes three illustrative case reports.