Clinical trials are the final clinical research phase necessary for the Food and Drug Administration (FDA) to approve a treatment for use in humans. The clinical testing of experimental drugs is normally done in three phases, each successive phase involving a larger number of people.

Phase 1 studies are primarily concerned with assessing the drug's safety and establishing a maximum tolerated dose for the drug. This initial phase of testing in humans is done in a very small number of volunteers. Sometimes, healthy adults without disease are tested. Other times, patients with end-stage disease are tested. For example, in initial Phase 1 trials testing the safety of retinal cell transplantation, patients who were already blind were tested so as not risk the loss of existing vision in patients who still had even very little visual function.

Phase 2 studies are initiated once a drug is found to be safe. In a Phase 2 study, the effectiveness of a given drug or treatment is evaluated. The duration of a Phase 2 study depends greatly on the nature of the treatment being tested and the specific disease. Phase 2 studies can involve large numbers of patients with several medical centers around the country participating in the trial.

Phase 3 studies allow investigators to better gauge the effectiveness and side effects of a drug in a large population of diverse patients. The large-scale testing provides the pharmaceutical company and the FDA with a more thorough understanding of the drug's effectiveness, benefits, and range of possible adverse reactions. In addition, Phase 3 studies are useful in comparing the new treatment against existing standard treatments.

To learn more about the clinical trials underway for inherited retinal diseases, visit The site lists comprehensive information about relevant trials including contacts.

The Foundation Fighting Blindness maintains a patient registry,, that may be used to help identify clinical trial participants. The registry is designed to collect basic information about individuals with retinal degenerative diseases such as retinitis pigmentosa, macular degeneration, Stargardt disease, Usher syndrome, and related diseases. When critical information about a specific disease or clinical trial becomes available, the Foundation will alert individuals in the registry via email and/or regular mail. The registry also provides crucial statistical information to our researchers and helps the Foundation obtain financial support for research projects and educational services.

While you may receive occasional correspondence or contact directly from the Foundation, your personal information will never be released to any outside organization without first receiving your informed consent. By participating in this registry you can help speed the pace of research and be assured that you are staying in touch and informed.  If you are interested in participating in the Foundation Fighting Blindness patient registry, visit