Computer Modelling of the actions of Extraocular Muscles

Abstract

The mechanical basis of the actions of the extraocular muscles is examined. A number of assumptions, which are required to specify the mechanical constraints on the actions of the muscles, are described. different assumptions about the way in which the extraccular muscles act are evaluated by comparing a set models of extraocular muscle cooperation, each of which  differ by just one assumption, against clinical data from patients with isolated nerve palsies. Three applications of the model based on the most appropriate assumptions, are described. Firstly, the Hess screen test of oculomotility is investigated by calculating the mechanical actions of the muscles along the lines of the Hess chart. Secondly, alternative theories concerning the muscular factors underlying A and V syndromes are compared by using the model to predict the deviation that should occur according to each theory. Thirdly, a computer based ophthalmotrope is used to demonstrate geometrical limitations on the amount of recession and transposition surgery that can be performed on the muscle insertions.