Effect of testing position on dynamic visual acuity.

OBJECTIVE

To investigate the effect of altering testing position on dynamic visual acuity (DVA) in vestibulopathic adults.

STUDY

DESIGN

Quasiexperimental research.

SETTING

Outpatient vestibular program.

PATIENTS: Twelve vestibulopathic adults with impaired DVA in the sitting position.

METHODS

DVA scores were collected during (1) sitting, (2) standing comfortably, and (3) semitandem standing as subjects viewed a vision (E) chart 3.48 m in front of them. DVA was obtained as the head was passively moved by the evaluator at a frequency of 1.5 Hz in both horizontal and vertical directions. A further subgroup of subjects (n=5) was retested after performing the "viewing x1" gaze stability home exercise four times daily (1 minute duration in the horizontal direction while sitting) for 2 months.

MAIN OUTCOME MEASURE: Noncomputerized DVA score.

RESULTS

The DVA score remained constant independent of testing position as the Friedman test did not reveal any significant differences in the DVA scores in the horizontal or vertical direction. Subjects who improved after performing the viewing x1 exercise in the horizontal direction in the sitting position tended to have the same improvement in DVA in all three positions.

CONCLUSIONS

The results of this study show that DVA score is independent of testing position. This is clinically important since it shows that the results of DVA testing in one position are valid for other positions and that subjects can be trained to improve their DVA in a sitting posture while having carry-over effects to other, more challenging postures.