The effects of caffeine on near point plus acceptance

Forty-two university students participated in a study of reading with +0.50 sphere or yokes prism base down for overconvergence and base up for underconvergence. Sixty-four percent of the group improved with a mean of +10.79 wpm. The level of coffee consumption of each student was recorded. A negative correlation existed between the intake of caffeine and reading improvement, r = -.81, p less than .001. Two students reduced their coffee consumption and transformed their loss in words per minute to a significant gain. A double-blind protocol was used in this study. A placebo lens (plano) controlled for subject and investigator bias. The relationship between caffeine and accommodation was investigated by means of a monocular test through a +4.D sphere. The location of the blur point was indicative of the state of tonicity of the ciliary system. Pre- and post-tests of the blur point for 14 subjects who were tested before and after consuming 150 mg of caffeine showed a significant change. The experimental group showed an increase of -0.52D while the control group showed a change of +0.36D. r = .781, p less than .01.