The method and the sequence of accommodative stimuli are two factors affecting the steady-state accommodative response. This study investigated the possible effects of these two factors on the accommodative stimulus response curves (ASRCs) and compared three indexes to evaluate ASRC in the different stimulus conditions.
In this study, we investigated the difference in the accommodative stimulus response curves under six stimulus conditions. The ASRCs of 10 emmetropes were measured when the accommodative stimulus (AS) was induced using three methods: negative lenses, positive lenses, and a Badal stimulator; and the stimulus was presented using two sequences: ascending and descending sequences. Three indexes, accommodative error area (AEA), accommodative error index (AEI), and the slope of ASRC, were used for comparison.
The accommodative error was larger when accommodative stimulus was presented in the ascending sequence than in the descending sequence (p < 0.05) in the Badal stimulator method whenever AEI, AEA, or the slope of ASRC was used. The ASRCs elicited with positive lenses were more accurate than that elicited with negative lenses or the Badal stimulator when AEA and AEI were used. However, when the slope of the ASRC was used, the result was not significant.
The results suggest that the accommodative response in the steady state may be affected by the method used for inducing AS and the sequence of AS presented. The AEA is suggested to be used in the evaluation of the accuracy of the ASRC in future studies.