The negative directional aftereffect associated with adaptation to the prismatic effects of spectacle lenses

Purpose: To determine whether subjects would demonstrate a negative directi onal aftereffect in a sparse visual environment after being trained to poin t accurately through a spectacle lens. Methods: Subjects were made myopic u sing a contact lens and then the myopia was corrected with a spectacle lens , Pointing behavior was used to assess directional localization. Training w as carried out by showing subjects their pointing errors. Results: Seven of 10 subjects demonstrated a negative directional aftereffect after spectacl e lens adaptation. Conclusions: The presence of a negative directional afte reffect indicates that some patients who switch between spectacles and cont act lenses can accurately localize objects only in one condition. Patients who do not demonstrate a negative directional aftereffect may be able to co rrectly localize objects with both spectacles and contact lenses.