Crystalline lens power in myopia.

Growth of the eye shows a coordinated pattern whereby the reduction in refractive power of the cornea and crystalline lens tends to reduce the myopia that would otherwise result from the normal increase in axial length. There is some controversy as to whether the reduction in crystalline lens power is influenced by the refractive state of the eye, i.e., an active role in the emmetropization process, or is simply related to the changing lens dimension occurring with growth. We measured ocular dimensions and determined the crystalline lens powers in 19 myopes and 19 emmetropic subjects matched for age, gender, and ethnic origin. No significant difference was found in corneal radius of curvature for the two groups, but there was a significant difference (p < 0.05) in crystalline lens power of 2.30 D. These results suggest that greater compensation for axial elongation of the eye was afforded by the decrease in crystalline lens power than by corneal flattening.