Which of the following is NOT a reason for discrepancy between empirical and diagnostic fits?

• A. Patient noncompliance with wear schedule
• B. inaccurate refraction
• C. inaccurate Ks
• D. lens flexure

Answer: (A)

The main idea is that discrepancies between the predicted, empirical fit and the actual diagnostic fit come from errors in the measurements used to design the lens or from how the lens behaves on the eye. If the refraction used to determine the lens power is inaccurate, the chosen lens won’t align optically as predicted, creating a mismatch. If the keratometry readings (Ks) are off, the base curve and sagittal height are not suited to the cornea, so the lens sits differently than expected. If the lens flexes on the eye, its shape and position change under the eyelids, also altering the fit from what the empirical model anticipated. In contrast, patient noncompliance with the wear schedule doesn’t directly change the geometric or optical relationship between the lens and the cornea during a fitting session; it may affect comfort or ocular surface health over time, but it isn’t a direct cause of a mismatch between empirical and diagnostic fits.