Abstract
Purpose::
To compare the accommodative response (AR) curves measured with different stimulus conditions.
Methods::
ARs were measured under 6 different stimulus conditions for each of 10 emmetropic optometry students. The 6 conditions comprised 3 techniques to create the accommodative stimulus (AS), i.e. the subject viewed through plus lenses, minus lenses, and a Badal stimulator. The AS was presented in 2 ways, i.e. ascending and descending orders in 0.50 D steps in each technique. In all conditions, the AR was measured with a Canon R-1 optometer from the subject’s right eye while the left eye was occluded. The average accommodative response for each stimulus condition was computed as a function of the accommodative stimulus using a 3-degree polynomial equation. Repeated ANOVA was applied for data analysis.
Results::
Statistical results showed that the ARs measured with the 3 methods were significantly different (F = 6.13, p = 0.0064). However, the difference in ARs between ascending and descending orders was not significant (F = 0.12, p = 0.73). Fisher’s LSD test was then applied to compare the difference between variables. In the descending sequence, the difference of the plus lens conditions from the minus lenses and Badal stimulator conditions was in the constant coefficient of the polynomials (all p < 0.01). In the ascending sequence, the difference of the plus lens conditions from the minus lenses and Badal lens conditions was in the constant and first order coefficients of the polynomials (all p < 0.01). The difference in the polynomial coefficients between minus lenses and Badal stimulator conditions was not significant except in the first order coefficient and the descending sequence (p < 0.05).
Conclusions::
AR was not affected by ascending or descending sequences in changing AS. However, using plus lenses to change the AS may lead different ARs compared with using minus lenses or a Badal stimulator.
Keywords: ocular motor control • myopia