 13. Contact lens wearers must discontinue the use of contacts for an appropriate period of time to ensure that their corneas are stable before screening measurements are performed. For rigid gas permeable RGP lenses, it is at least 24 weeks before accurate imaging measurements can be performed. Study doctor will assess patient findings and determine how long RGP lens wear must be discontinued prior to surgery. For soft contact lenses, it is at least 3 days prior to study measurements. 