The research treatment has been well tested in laboratory and animal studies, but the side effects in patients are not completely predictable. Phase II trials determine the effectiveness of a research treatment after safety has been evaluated in a Phase I trial. Patients are closely observed for an anti-keratoconus effect by careful measurement of KC sites present at the beginning of the trial. In addition to monitoring patients for response, any side effects are carefully recorded and assessed. Phase III trials require entry of large numbers of patients.
Some trials enroll thousands of patients.
All patients in Phase III trials are monitored closely for side effects, and treatment is discontinued if the side effects are too severe. However, there are some risks. No one involved in the study knows in advance whether the treatment will work or exactly what side effects will occur. That is what the study is designed to discover. While most side effects will disappear in time, some can be permanent or even life-threatening.