What is essential for proper fitting of contact lenses regarding corneal measurement?

For the proper fitting of contact lenses, corneal curvature measurement is essential because the shape of the cornea directly affects how contact lenses sit on the eye. The cornea is not a perfect sphere; it has different curvatures that can affect the fit and comfort of the lens. By accurately measuring the curvature, practitioners can choose lenses that appropriately conform to the individual's corneal shape, ensuring that the lenses provide stable positioning and optimal vision correction.

In contrast, pupil diameter measurement is more relevant for certain types of lenses, particularly those that are larger or smaller than standard. However, it is not a primary factor in ensuring that the lens fits well on the cornea. Anterior chamber depth measurement could inform a practitioner about the overall eye structure and help with determining certain lens types, but it is not directly related to the lens fit itself. Refractive index measurement pertains to how light refracts through various media but does not influence the physical fit of the contact lens on the cornea.