Visual field dependence in elderly fallers and non-fallers.

Two tests of visual field dependence (a measure of reliance upon the spatial framework provided by vision in the perception of the upright)--roll vection and the rod and frame test--were administered to 136 participants aged fifty-nine to ninety-seven years. It was found that the fifty-nine participants who had experienced one or more falls in the past year were significantly more visually field dependent in both tests compared with the seventy-seven participants who had not fallen. Mean error in perception of the true vertical in the rod and frame test was 20.7 degrees for the fallers and 17.2 degrees for the non-fallers. Mean error in perception of the true vertical in the roll vection test was 6.6 degrees for the fallers and 3.6 degrees for the non-fallers. The test of roll vection was the better discriminator between fallers and non-fallers, which may be due in part to less misunderstanding of the required task by the participant. The results suggest that tilted or rolling visual stimuli may be factors leading to postural instability and falls in the elderly. The findings support the claim that greater dependence on visual information shown by fallers may be the result of reduced proprioceptive and vestibular function resulting from increased age and chronic health problems.