Corneal topographic data: its use in fitting aspheric contact lenses.

We conducted a retrospective assessment of the fitting characteristics obtained with the Boston Envision rigid gas permeable contact lens to determine the best parameter for selecting an initial base curve. We fit 13 subjects (11 successfully) with the Envision lens, using computerized videokeratoscopy to evaluate prefitting corneal topography. The selected base curve of the lenses fit most closely to the flattest K at the 5 mm zone. This value may be the best parameter for selection of an initial base curve, especially in eyes with keratoconus. Using topographic information may give quicker and more accurate initial fits than keratometry alone.