Keratoconus and penetrating keratoplasty fittings are best accomplished by which of the following methods?

Diagnostic fitting is the preferred method for keratoconus and penetrating keratoplasty fittings due to its ability to provide a highly individualized assessment of the patient's eye shape and refractive needs. This method involves using trial lenses to evaluate fit and comfort in real-time, allowing practitioners to make necessary adjustments based on the unique corneal topography and the individual's response to the lenses.

In cases of keratoconus, the cornea is often irregularly shaped, which can complicate lens fitting. By employing a diagnostic fitting approach, practitioners can assess how different lens designs perform on the actual eye, thereby selecting the most appropriate lenses—whether they be rigid gas permeable (RGP) or scleral lenses—that will offer the best vision correction and comfort for the patient.

Although other methods may provide some degree of guidance, they do not offer the same level of precision and adaptability. For instance, using nomograms (a mathematical model for estimating lens parameters) may not account for the unique variations found in each patient's cornea. Relying solely on keratometry readings (Ks) and the prescription (Rx) might overlook critical fitting aspects, and molded impressions, while useful in some contexts, do not provide the dynamic feedback necessary for optimizing fit in cases