In previous studies we have shown that subjects with normal binocular vision adapt to prism-induced heterophorias. In this study we have continued the work by investigating whether the oculomotor system can also adapt to lens-inuced heterophorias. It was found that subjects gradually adapted to the esophoria induced when viewing a distance chart through negative lenses. Adaptation also occurred to lens-induced esophoria and exophoria at near, while at distance, where the visual feedback was unaltered, the phoria remained virtually constant. These findings demonstrate the flexibility of the oculomotor system.