Vergence adaptation in clinical vergence testing.
BACKGROUND
The purposes of this investigation were to determine whether vergence adaptation occurs after vergence range testing and vergence facility testing and to determine whether vergence adaptation correlates with the results of these tests.


METHODS
Thirty subjects participated in 3 testing sessions on different days. During each session 1 of the following was tested: base-out prism bar vergences, vergence facility (12 base-out/3 base-in binocular prism flippers for 1 minute), and 5 minutes viewing with 6 prism diopters of base-out prism. Before and after each test, the near phoria was measured using the modified Thorington method.


RESULTS
There was no correlation between the amplitude of the vergence ranges and the amplitude of vergence facility. Significant vergence adaptation as indicated by an esophoric shift of approximately 3 prism diopters occurred in all testing sessions. The amplitude of vergence adaptation did not correlate with either the amplitude of the blur vergence range or vergence facility. There was a significant correlation between the amplitude of vergence adaptation and the amplitude of the break vergence range.


CONCLUSIONS
The lack of correlation between the blur vergence range and the vergence facility is not likely because of vergence adaptation. The lack of correlation between the break vergence range and the vergence facility may be in part caused by vergence adaptation.
McDaniel
Catherine
C
University of Houston College of Optometry, Houston, Texas 77204-2020, USA. cmcdaniel@optometry.uh.edu
Fogt
Nick
N
D000328:Adult; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D012044:Regression Analysis; D015357:Vision Disparity / Q000502:physiology*; D014787:Vision Tests