Study design issues in a corneal reshaping contact lens myopia progression study.

Advances in contact lens design have led to corneal reshaping contact lenses that can be worn at night to temporarily reduce myopia so that patients can see clearly without glasses or contact lenses. Children are able to wear corneal reshaping contact lenses, but we do not know how they may affect the progression of myopia. A myopia control study with corneal reshaping contact lenses poses study design problems that other studies do not encounter because they temporarily reduce the refractive error. A discussion of the choice of primary outcome and control group will highlight some of these unique study design issues.