Vestibulo-ocular reflex during magnified vision: adaptation to reduce visual-vestibular conflict.

This report describes the short-term effect of 2.2X telescopic spectacles on the vestibulo-ocular reflex (VOR) in seven volunteers. VOR gain was initially measured in darkness and light during passive sinusoidal rotations. Subjects were then rotated in light for 15 min while wearing telescopic spectacles. Dynamic visual acuity (DVA), vision during head rotation, was measured with telescopic spectacles. Initial VOR gain in darkness was 0.74 +/- 0.10 (mean +/- S.D.); VOR gain with unmagnified vision was 1.07 +/- 0.04. Initial VOR gain with magnified vision was 1.37 +/- 0.53. DVA was poorer than static acuity in three of four subjects. After adaptation, VOR gain in darkness increased to 0.83 +/- 0.12, with six of seven subjects exhibiting a gain increase of 7-23% (p less than 0.05 for 5). Adapted VOR gain with magnified vision was 1.54 +/- 0.25. Adapted performance was more consistent and oscillopsia was reduced. Adapted DVA improved 30-100% in four subjects. These changes indicate VOR adaptation to telescopic spectacles decreases visual-vestibular conflict.