Purpose: To evaluate the effect of newly designed positively aspherized progressive addition lenses (PA-PALs), which reduce both lag of accommodation and hyperopic defocus on the peripheral retina, on the progression of early-onset myopia.
Methods: Positively aspherized–PALs have near addition and high positive distance zone aspherization comparable to the addition power. One hundred ninety-seven children were enrolled, 6 to 12 years of age, with spherical equivalent refraction from −1.00 to −4.50 diopters (D). The children were randomized to receive one of three lenses: single vision lenses (SVLs), PA-PALs with +1.0 D addition, or PA-PALs with +1.5 D addition. Follow-up visits occurred every 6 months for 2 years. The primary outcome was myopia progression evaluated by cycloplegic autorefraction.
Results: One hundred sixty-nine (86%) children completed the follow-up. Statistical analysis of adjusted progression rates showed a mean (±SE) progression of −1.39 ± 0.09 D in the control group wearing SVLs at the 24-month visit. Statistically significant (P = 0.017) retardation of myopia progression (0.27 ± 0.11 D during 24-month period or reduction ratio of 20%) by +1.5 D add PA-PALs relative to the SVLs was found, which was within the range of the percentage efficacy of myopia retardation by the conventional PALs in earlier trials over the same follow-up period. Nearly all retardation occurred in the first 12 months with no significant efficacy in the second year. Positively aspherized–PALs with +1.0 D addition showed negligible efficacy.
Conclusions: To the extent that has been tested and that can be tolerated by wearers of spectacle lenses, the high positive aspherization of the distance zone added to PALs does not enhance their therapeutic efficacy in slowing myopia progression. (http://www.anzctr.org.au/ number, ACTRN12608000566336).