A comparison of the results of tonic and phasic vergence training.

Thirty-four healthy asymptomatic young adults were randomly divided into two groups. All subjects underwent training aimed at expanding the vergence ranges. The training in one group consisted of tasks emphasizing smooth, slow activities. The other group trained using quicker, stepwise, more phasic tasks. The vergence ranges were subjectively measured using a small (1.72 degree diameter) target in a major amblyoscope. The study lasted 6 weeks. The first 3 weeks served as a control period over which time the vergences proved to be stable. The training was done for 10 min on the weekdays of the last 3 weeks of the study. Analysis of the data indicates that the group training via the stepwise or phasic paradigm showed greater increases in both the positive and negative vergences. Both groups achieved substantial increases in both the negative and positive vergences. The significance of these results is discussed.