The author uses decision analysis methods to examine the implicit clinical and public policy of' providing most elderly patients with a new surgical technology treating senile cataracts. The analysis suggests that the limitations of the "best" empirical evidence adversely affect decision making. Failure to measure patient preferences is a key source of decision-making uncertainty. Hence, the nearly universal provision of the new technology is questionable. Because many clinical interventions have not been rigorously evaluated, decision analysis may have a significant role in clinical and public decision making.