Spatial aspects of vertical phoria adaptation.
Vergence adaptation to vertical disparity spreads to unadapted directions of gaze. The spatial spread function for prism adaptation was estimated from aftereffects of a vertical disparity presented at a single position. Constraints limiting the spatial spread of adaptation were investigated with two stimuli of opposite disparity (hyper and hypo), presented at two different eye positions with a separation that varied from 6 to 18 deg in either the horizontal or vertical meridian. On average, phoria adaptation to the single point paradigm spread uniformly across the entire 18 deg test field. A resolution limit for adaptation to the two point paradigm was demonstrated by a reduction of phoria aftereffects with decreasing target separation (crowding). Vertical phoria aftereffects were reduced more by horizontal than by vertical crowding. A disparity gradient limit was demonstrated for a fixed target separation by a reduction of gain (phoria change/stimulus disparity) with increasing stimulus disparity.
Schor
C
C
University of California, School of Optometry, Berkeley 94720.
Gleason
G
G
Maxwell
J
J
Lunn
R
R
D000221:Adaptation, Ocular / Q000502:physiology*; D000328:Adult; D005133:Eye Movements / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological; D013285:Strabismus / Q000503:physiopathology*; D015348:Vision, Binocular / Q000502:physiology