IMPORTANCE Myopia is a significant public health problem, making it important to determine whether a bifocal spectacle treatment involving near prism slows myopia progression in children. OBJECTIVE To determine whether bifocal and prismatic bifocal spectacles control myopia in children with high rates of myopia progression and to assess whether the treatment effect is dependent on the lag of accommodation and/or near phoria status. DESIGN, SETTING, AND PARTICIPANTS This 3-year randomized clinical trial was conducted in a private practice. A total of 135 (73 female and 62 male) Chinese-Canadian children (aged 8-13 years; mean [SE] age, 10.29 [0.15] years; mean [SE] myopia, −3.08 [0.10] D) with myopia progression of at least 0.50 D in the preceding year were randomly assigned to 1 of 3 treatments. A total of 128 (94.8%) completed the trial. INTERVENTIONS Single-vision lenses (control, n = 41), +1.50-D executive bifocals (n = 48), and +1.50-D executive bifocals with 3-Δ base-in prism in the near segment of each lens (n = 46). MAIN OUTCOMES AND MEASURES Myopia progression (primary) measured using an automated refractor following cycloplegia and increase in axial length (secondary) measured using ultrasonography at intervals of 6 months for 36 months. RESULTS Myopia progression over 3 years was an average (SE) of −2.06 (0.13) D for the single-vision lens group, −1.25 (0.10) D for the bifocal group, and −1.01 (0.13) D for the prismatic bifocal group. Axial length increased an average (SE) of 0.82 (0.05) mm, 0.57 (0.07) mm, and 0.54 (0.06) mm, respectively. The treatment effect of bifocals (0.81 D) and prismatic bifocals (1.05 D) was significant (P < .001). Both bifocal groups had less axial elongation (0.25 mm and 0.28 mm, respectively) than the single-vision lens group (P < .001). For children with high lags of accommodation (Ն1.01 D), the treatment effect of both bifocals and prismatic bifocals was similar (1.1 D) (P < .001). For children with low lags (<1.01 D), the treatment effect of prismatic bifocals (0.99 D) was greater than of bifocals (0.50 D) (P = .03). The treatment effect of both bifocals and prismatic bifocals was independent of the near phoria status. CONCLUSIONS AND RELEVANCE Bifocal spectacles can slow myopia progression in children with an annual progression rate of at least 0.50 D after 3 years. These results suggest that prismatic bifocals are more effective for myopic children with low lags of accommodation. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00787579

To determine whether bifocal and prismatic bifocal spectacles could control myopia in children with high rates of myopic progression.Methods: This was a randomized controlled clinical trial. One hundred thirty-five (73 girls and 62 boys) myopic Chinese Canadian children (myopia of Ն1.00 diopters [D]) with myopic progression of at least 0.50 D in the preceding year were randomly assigned to 1 of 3 treatments: (1) single-vision lenses (n = 41), (2) ϩ1.50-D executive bifocals (n = 48), or (3) ϩ1.50-D executive bifocals with a 3-prism diopters base-in prism in the near segment of each lens (n = 46). Main Outcome Measures: Myopic progression measured by an automated refractor under cycloplegia and increase in axial length (secondary) measured by ultrasonography at 6-month intervals for 24 months. Only the data of the right eye were used.Results: Of the 135 children (mean age, 10.29 years [SE, 0.15 years]; mean visual acuity, −3.08 D [SE, 0.10 D]), 131 (97%) completed the trial after 24 months. Myopic progression averaged −1.55 D (SE, 0.12 D) for those who wore single-vision lenses, −0.96 D (SE, 0.09 D) for those who wore bifocals, and −0.70 D (SE, 0.10 D) for those who wore prismatic bifocals. Axial length increased an average of 0.62 mm (SE, 0.04 mm), 0.41 mm (SE, 0.04 mm), and 0.41 mm (SE, 0.05 mm), respectively. The treatment effect of bifocals (0.59 D) and prismatic bifocals (0.85 D) was significant (PϽ.001) and both bifocal groups had less axial elongation (0.21 mm) than the singlevision lens group (P Ͻ.001).Conclusions: Bifocal lenses can moderately slow myopic progression in children with high rates of progression after 24 months.Applications to Clinical Practice: Bifocal spectacles may be considered for slowing myopic progression in children with an annual progression rate of at least 0.50 D.

The effect of positive-lens addition (0, +0.75, +1.50, +2.25, +3.00 D each eye) and base-in prism power (0, 1.5, 3 D each eye) on both near focusing errors and latent horizontal deviations was evaluated in 29 Chinese myopic children (age: 10.3 ± 1.9 years, refractive error: )2.73 ± 1.31 D). Accommodation response and phoria were measured by the Shin-Nippon auto-refractor (right eye) and Howell-Dwyer near phoria card at 33 cm with each of the 15 lens/prism combinations in random order. The initial accommodative error was )0.96 ± 0.67 D (lag) and near phoria was )0.

Ethnic Chinese children living in Canada develop myopia comparable in prevalence and magnitude to those living in urban East Asian countries. Recent migration of the children and their families to Canada does not appear to lower their myopia risk.