The influence of vergence adaptation on open-loop vergence dynamics.
The objectives of this experiment were to measure the effect of sustained convergence on the open-loop vergence peak velocity and open-loop vergence amplitude, and to assess the correlation between changes in the phoria and changes in open-loop vergence peak velocity induced by sustained convergence. Subjects sustained convergence on a target that required 12 degrees of convergence for 5 minutes. Convergence and divergence movements of 4 degrees from the 12 degrees convergent position were measured before and after sustained convergence. Following sustained convergence, the open-loop vergence peak velocity and vergence amplitude both increased for convergence (regression slope=3.68, r=0.47). Vergence velocity and vergence amplitude both decreased for divergence (regression slope=1.76, r=0.36). After sustained convergence, a convergent shift in the phoria was noted in most cases. This shift correlated with changes in open-loop peak vergence velocity more for convergence (regression slope=1.1, r=0.33) than for divergence (regression slope=0.71, r=0.22). The results might be due to shifts in disparity detection brought about by the period of sustained convergence.
Satgunam
PremNandhini
P
The Schepens Eye Research Institute, Harvard Medical School, Boston, MA 02114, USA. premnandhini.satgunam@schepens.harvard.edu
Gowrisankaran
Sowjanya
S
Fogt
Nick
N
D000065:Accommodation, Ocular / Q000502:physiology; D000221:Adaptation, Ocular / Q000502:physiology*; D000328:Adult; D003290:Convergence, Ocular / Q000502:physiology*; D005133:Eye Movements; D005260:Female; D005403:Fixation, Ocular; D005583:Fourier Analysis; D006801:Humans; D008297:Male; D010775:Photic Stimulation; D011930:Reaction Time; D012030:Refractive Errors; D055815:Young Adult