The development of adaptive head movements following enucleation.

Recent work in our laboratory has revealed that enucleated patients produce large lateral and vertical head movements during visually guided grasping. These movements may allow them to maximise the use of retinal motion cues in planning and controlling their grasp. The aim of the present study was to determine whether the tendency to produce these adaptive head movements increases as a function of time since enucleation. We tested a group of 12 enucleated patients in whom the time between surgery and testing varied from 2 weeks to 35 years (mean = 11.2 years). These patients were required to reach out and grasp oblong blocks of different sizes at different distances. Correlational tests revealed an increase in the proportion of self-generated lateral and vertical head movements versus forward head movements as a function of post-enucleation time (r(s)(12) = 0.68, p < 0.025 and r(s)(12) = 0.65, p < 0.025, respectively). This suggests that enucleated patients may be adapting to living with one eye by learning to increase the proportion of their lateral and vertical head movements during the performance of skilled motor acts.