Establishing non-inferiority margins in myopia management contact lens trials with an active control.

The myopia control field stands at an ethical crossroads. Withholding proven soft contact lens interventions in control arms of myopia management trials is increasingly viewed as ethically questionable and operationally challenging, particularly given that MiSight 1-day contact lens has demonstrated efficacy in at least four randomised controlled trials. The recent methodological evolution towards non-inferiority trials against an established control rather than a placebo (single vision) is a welcome change. However, this shift raises a critical challenge: setting non-inferiority margins that are both clinically meaningful and statistically robust.