Abstract
Purpose: :
To test whether the active horizontal angular Vestibulo–Ocular Reflex (VOR) is capable of monocular adaptation in normal human adults as a result of induced anisometropia, without the confound of blur.
Methods: :
Nineteen participants between 19 and 45 years of age (11 female, 8 male) wore a contact lenses/spectacles combination for 4 hours. The power of the spectacle was +5.00 diopters (D) (magnified images 8.65%) in front of the right eye and –5.00D (minified images 5.48%) for the left eye. The power of the contact lenses was equal to the subjects’ habitual correction, summed with the opposite power of the spectacle lens. Eye and head position data was collected in complete darkness, in one–minute trials before adaptation and every 30 minutes for 2 hours after adaptation, using a video–based eye tracking system, linked to head tracker. The data was analyzed offline using Fast Fourier Transform in MATHCADTM 11.1 software to calculate VOR gain. VOR gain was compared between the right eye and left eyes for the trials before and after adaptation.
Results: :
In the first post–adaptation trial, a significant decrease in VOR gain (≈ 6%) occurred in the left eye in response to the miniaturizing lens. The right eye VOR gain did not show a significant change in the first post–adaptation trial (≈2% decrease). During the remaining trials in the 2 hour follow–up time, both eyes showed a significant decrease in VOR gain compared to the baseline trial.
Conclusions: :
There was monocular adaptation of VOR in response to the combined contact lenses/spectacles, but only in response to the minifying lenses.
Keywords: vestibulo-ocular reflex • eye movements • ocular motor control