Corneal curvature measurement is vital in determining which parameter when fitting a contact lens?

Corneal curvature measurement is crucial for determining the base curve of a contact lens. The base curve refers to the curvature of the back surface of the contact lens, which should closely match the curvature of the cornea to provide optimal fit and comfort. When the base curve is aligned correctly with the cornea, it helps the lens to sit properly on the eye, ensuring better stability, minimizing discomfort, and allowing for appropriate tear exchange under the lens.

An accurate corneal curvature measurement allows practitioners to select a base curve that will fit well on a patient’s eye, thereby reducing the risks of complications such as corneal abrasions or infections. This relationship between corneal curvature and lens base curve is fundamental in contact lens fitting, as lenses that are too flat or too steep can lead to issues in lens positioning and ocular health.

The other parameters mentioned, while important in contact lens fitting, do not rely directly on corneal curvature measurements. Diameter refers to the overall size of the lens, lens thickness relates to its physical geometry, and power denotes the lens's refractive strength — none of which are inherently determined by the corneal curvature.