Possibility for Classifying Paralytic Strabismus Based on Gaze Directions Estimated from Ocular Motility Photographs

Abstract

Paralytic strabismus is caused by disorder of the nerves controlling the extraocular muscles, and thus is classified by the disordered nerves into three types: abducens paralysis, trochlear paralysis, and oculomotor paralysis. These types are diagnosed from ocular motility photographs of patients looking in different positions, because misalignment is observed between the gaze directions of the two eyes to look in the positions using the extraocular muscles controlled by the disordered nerves. This article discusses the possibility for classifying the types of paralytic strabismus from ocular motility photographs by obtaining gaze directions from the photographs and identifying the types from the obtained gaze directions. The gaze directions are estimated as the directions such that the intensity patterns around the regions where the iris of the eye model in those directions appear on the image plane are closest to the typical patterns around the iris. The types of paralytic strabismus are identified from the estimated gaze directions by Balanced Random Forest. In our experiments, the error of estimated gaze directions was about 5 to 9 degrees, and the accuracy of the classified types was about 70 to 90 percent. These results show the possibility for the above classification.