[Development and training of monocular motor control]

Misalignment of the visual axes of the eyes observed in strabismus may result from sensory, motor, and/or central nervous system disorders. The functional properties of a technique designed to increase, through training, the monocular motor control of normal human subjects was evaluated, the ultimate goal being obviously to apply the technique to cases of minor strabismus. The subject is seated in front of a television screen. A diaphragm extending from the subject's head to the screen divides the picture into two visually separated half fields. A micro-computer was programmed to project two patterns on the screen, made up of vertical green and grey bars (spatial frequency, 3 deg.). Displacement of the two visually superposable half fields could be independently achieved. The subject's task was to fixate, with one eye, the corresponding half field maintained stationary and track, with the other eye, the motion of the second half field. Perfect fusion of the two half fields has to be preserved during movements of the mobile half field over 2 to 6 degrees at a frequency of 0.4 Hz. The results show that after a few training sessions, subjects developed a high gain monocular motor control. This observation suggests that the method may be used as therapy to correct minor strabismus with or without anomalous retinal correspondence, and offers the possibility to study static and dynamic characteristics of Panum's areas and particularly their modifications as a function of training of monocular motor control.