The CLAMP Study uses a run-in period to enroll only children who are able to adapt to rigid contact lens wear into the study. This decreases the number of children who drop-out of the study because they cannot adapt to rigid contact lens wear. Once children show that they are able to wear rigid contact lenses, they are enrolled in the study and randomly assigned to wear rigid gas permeable contact lenses or soft contact lenses. Both groups are then examined each year for three years to determine which group progresses the most in nearsightedness.