Postural control in blinds and in Usher's syndrome.

The postural control mechanisms were evaluated in 10 blinds and in 10 subjects with Usher's syndrome. The results were compared with 27 age matched healthy volunteers. In visual conditions the subjects with Usher's syndrome performed worse, but in nonvisual condition they performed equally well as the controls. The results were the same irrespective of whether the tests were performed on a rigid surface or foam rubber covered surface. The blinds and controls performed equally well on the bare surface, but the blinds performed significantly better on the foam rubber covered surface. The results indicate that in subjects with Usher's syndrome the vestibulo-cochlear degeneration is well compensated but the postural stability aggravated due to retinal degeneration. Blind subjects have a better postural control than their seeing referents, but the difference is only evident in situations in which the postural control is hampered by surface perturbation.