The effect of changing from glasses to soft contact lenses on myopia progression in adolescents.

At the end of a clinical trial of bifocals as myopia treatment, subjects were allowed to select any type of optical correction they wished and were asked to return in 1 year. This report gives results of that last examination with emphasis on how progression rates differed between those remaining in their original type of glasses compared with those who switched to soft contact lenses. We found that myopia progressed at an age-adjusted average rate of 0.74 D in 19 children who switched to soft contact lens wear compared with 0.25 D for 24 children remaining in glasses (p < 0.0001). Increased growth of the vitreous chamber appeared to account for much of this excess myopia progression, although the difference in that variable did not reach statistical significance (p = 0.101). We also noted a 0.203 D steepening in the corneal curvature in contact lens wearers compared with spectacle wearers whose corneas steepened very little (0.014 D, p = 0.007). Soft contact lens wear was also accompanied by a greater change in the near-point phoria which moved 4.5 prism dioptres in the exo direction compared with spectacle wearers who experienced only a 1.4 prism dioptre divergent shift (p = 0.048).