Postural sway during retinal image stabilisation.

Posturographic measurements using a piezoelectric platform were made in normal subjects while wearing a combination of spectacle and contact lens providing partial stabilisation of the retinal image (RIS). The amount of postural sway seen while wearing the device at rest is intermediate between the "normal vision" and "eyes closed" conditions, and increases with increasing amounts of RIS. However, when large active head-and-eye movements are performed, postural sway is dramatically increased when using RIS, and is then worse than while performing the same task in the "eyes closed" condition. It is concluded that patients who use the partial-RIS device for the treatment of severe oscillopsia may benefit only when performing tasks in which the head is relatively still, such as reading, writing or watching TV. It is also proposed that the partial-RIS device can serve as a model in normal free-standing subjects for the postural effects of oculomotor disorders.