Rigid Contact Lens Fitting Relationships in Keratoconus

We appreciate the interest in our work of Drs. McMonnies and Boneham. Unfortunately, data on the specific “age of the patients’ current contact lens fittings” are not available. We believe that it is very difficult for keratoconus patients to identify when they were actually fitted with the specific pair of lenses that they are wearing and that such data, if collected, would have been highly unreliable. However, we do ask the patients whether they underwent a contact lens refitting in the previous 12 months. These data are not subjected to rigorous quality control (i.e., we do not verify their response by searching their medical records for evidence of a refitting). It turns out that 64% of the patients report having undergone a fitting in the previous 12 months, which indicates that the data on the fitting relationship of these lenses is current in the majority of patients. Table 1 compares the degree of flatness of fit in the self-reported refitted patients compared with those who did not report a refitting in the preceding 12 months. There is no statistically significant difference between the contact lens fitting relationship as indicated by the difference between the first definite apical clearance lens (FDACL) and the patient's habitual contact lens base curve (Student's t-test, p = 0.64). We estimate a statistical power of 0.99 at this sample size to detect at least a 1.00 D difference between these two groups. Karla Zadnik Timothy B. Edrington Loretta B. Szczotka Joseph T. Barr Joel F. Achtenberg Dennis C. Burger Andrea M. Janoff Harald E. Olafsson John W. Boyle Mae O.