Why is measuring corneal curvature essential for contact lenses?

Measuring corneal curvature is crucial for fitting contact lenses because it helps ensure that the lens rests appropriately on the tear film, which is the thin layer of moisture that covers the cornea. The tear film plays a vital role in providing comfort and maintaining the health of the cornea, as well as enabling clear vision.

A proper fit of the contact lens on the tear film allows for even distribution of tears, thus providing adequate lubrication and preventing dryness or irritation. This fitting consideration also ensures that the lens does not disturb the natural shape of the cornea or impede vision. Furthermore, by resting on the tear film, the lens can remain stable during blinking, allowing for optimal visual acuity and comfort throughout its wear.

If the lens were to touch the conjunctival surface or rest directly on the cornea instead of the tear film, it could lead to discomfort, reduced vision quality, and potential damage to the eye. Therefore, understanding the curvature of the cornea enables practitioners to design and select contact lenses that fit securely and comfortably while functioning effectively in the tear film environment.