[Development of the AC/A ratio following surgery of accommodative esotropia]

Whether surgery should be used to correct for accommodative esotropia is still largely debated among strabologists. Fincham's theory (Fincham and Walton, 1957), describing the interaction between accommodation and vergence control systems (accommodative vergence and vergence accommodation), has been extensively studied. Models suggest that weakening of the accommodative vergence should correct esotropia. To test the model proposed by Semmlow (1981), we compared AC/A ratios in esotropic children and age-related normals (orthophoric) and monitored AC/A ratios for immediate (first week) and long term (1-2 months) changes in esotropic children following surgical correction. The AC/A ratio was determined at near and far. The accommodation stimulus was modified using lenses. The slope of the regression line between accommodation stimulus and disparity provided a measurement of AC/A ratio. Preliminary results show a normalisation of AC/A ratio occurring during the first month after surgery, supporting Semmlow's model and validating surgery as a means to correct for accommodative esotropia.