Cooperative clinical trials. The Second Ticho Memorial Lecture.

As exemplified by the collaborative Diabetic Retinopathy Study, all the appropriate techniques involved in a clinical trial-random assignment of treatment, appropriate controls, and avoidance of investigator bias-should be incorporated during the earliest testing of a new therapy for a chronic disease, for the sake of the patient and for the progress of medical science. This approach to clinical trials in the testing of new ocular therapies can provide the most scientifically sound and rational therapy to the patient.