Effects of prism-induced, accommodative convergence stress on reading comprehension test scores

Forty-eight binocular, non-presbyopic optometry students, unfamiliar with the purposes of the study, were provided with several matched passages of material to read in a given time sequence. Multiple choice questions were to be answered at the completion of each reading passage. These were administered in a randomly counterbalanced presentation (a b b a) utilizing either base-in prism or plano lenses in spectacle form. The results of this experiment showed a statistically significant lower comprehension rate with the base-in prism lenses in place as evidenced by fewer correct answers to the questions following the reading passages. This effect was found to be greater for the longer reading passages followed by a greater number of questions to be answered.