Hard contact lenses change corneal shape and for this reason you need to be out of them for a significant amount of time to allow the cornea to regain its normal shape prior to surgery and the scans. An old rule of thumb is that the patient needs to stay out of hard lenses one month per decade of usage, at a minimum. So if you have been in them for 30 years, that would be a minimum of 3 months you need to be out of them. However, we do look for stability in the curvature and if real stability occurs sooner than that, we will be ready. Many times the patient can be refit for a few months in soft contacts to allow the cornea to start to change shape, and then move to glasses for the remaining month or so. The real issue is when the curvature becomes stable and we test repeatedly during this “rehab” time to see when the corneal shape stops changing.