Evaluation of the placebo effect in optometry.

&NA; The placebo effect plays a large role in the effectiveness of optometric therapy as it does in therapies used by members of other healing arts professions. Rather than attempting to avoid placebo effects as a result of their various therapies, healing arts practitioners should strive to maximize the positive placebo effects as well as positive specific effects of their therapies. The evaluation of the importance of the placebo effect in determining the results obtained with any given therapy is difficult. In the last twenty years adequate experimental techniques utilizing statistical evaluation have been employed to evaluate the real effectiveness of some types of drug therapy in medicine. However, as of today, the vast majority of medical therapies have not been subjected to such evaluation. The same absence of evaluation exists with optometric therapies. The absence of evaluation does not mean that a therapy should be avoided, but practitioners using the therapy should remain aware of the limits of knowledge.