The future of clinical trials of myopia control.

In the field of myopia control, effective optical or pharmaceutical therapies are now available to patients in many markets. This creates challenges for the conduct of placebo-controlled, randomised clinical trials, including ethics, recruitment, retention, selective loss of faster progressors and non-protocol treatments: Ethics: It is valid to question whether withholding treatment in control subjects is ethical. Recruitment: Availability of treatments is making recruitment into clinical trials more difficult. Retention: If masking is not possible, parents may immediately withdraw their child if randomised to no treatment. Selective loss: Withdrawal of fast progressors in the control group leading to a control group biased towards low progression. Non-protocol treatment: Parents may access other myopia treatments in addition to those within the trial. We propose that future trials may adopt one of the following designs: Non-inferiority trials using an approved drug or device as the control. The choice will depend on whether a regulatory agency has approved the drug or device. Short conventional efficacy trials where data are subsequently entered into a model created from previous clinical trials, which allows robust prediction of long-term treatment efficacy from the initial efficacy. Virtual control group trials based on data relating to axial elongation, myopia progression or both, accounting for subject's age and race. Short-term control data from a cohort, for example, 1 year or less, and applying an appropriate, proportional annual reduction in axial elongation to that population and extrapolating to subsequent years. Time-to-treatment-failure trials using survival analysis; once a treated or control subject progresses or elongates by a given amount, they exit the study and can be offered treatment. In summary, the future development of new treatments in myopia control will be hampered if significant changes are not made to the design of clinical trials in this area.