Variations of refractive error during the first year of contact lens wear.

The variations of refractive errors during both hard, hydrophilic and silicone lens wear were significantly correlated in the 2 eyes of each individual. In each lens group the mean changes of spherical and cylindrical refractive errors were small (-0.458D-+0.250D and -0.325D-+0.056D, respectively). Considerable individual refractive changes occurred (spherical change: -3.0D-+1.5D, cylindrical change: -2.5D-+1.0D). However, only 2 subjects noticed spectacle blur and a normal visual acuity was always obtained by spectacle refraction immediately after lens removal. This indicated that clinically significant distortion of the central cornea did not take place. Hydrophilic lens wearers showed an increasing myopia during lens wear. Otherwise the refractive changes were not significantly influenced by the duration of lens wear. Refractive changes appeared to be significantly correlated to changes of the central anterior corneal curvature, the ratio of dioptric changes being about 1:1.