The present study tests the hypothesis that Stulln eyedrops improve accommodative functions
by improving the short term facility of ciliary muscles that can be transferred into
long-term adaptation. To test this, the investigators propose to conduct a prospective
randomized control trials where participants with accommodative dysfunctions are randomly
assigned to four groups: control, Stulln only and Stulln plus vision training. The
investigators' theory predicts that the efficacy of Stulln will be augmented by vision
training.