Corneal refraction: relative effects of each corneal component.

The refractive power of the cornea may change after wearing contact lenses and as a result of disease or surgery. Each corneal component that contributes to the refractive power was analyzed and their relative significance was determined by comparing the refractive effects of a 10% change. In order of magnitude, the effect of a 10% change in each component was as follows: anterior corneal curvature (4.87 D), index of refraction (1.87 D), depth of anterior chamber (1.20 D), posterior corneal curvature (0.62 D) and corneal thickness (0.01 D). Refractive changes are the result of increases and decreases of each component and the total effect is the sum of the individual changes in each component.