Abstract
BACKGROUND: To compare the effects of ordinary spherocylindrical spectacle lenses versus defocus incorporated multiple segments (DIMS) spectacle lenses on ocular alignment and binocular visual functions in teenagers with myopia over a 2-year period. METHODS: 120 myopic teenagers aged 12–18 years were randomly allocated to wear either ordinary spherocylindrical single vision spectacle lenses (SV group, n = 60) or DIMS spectacle lenses (DIMS group, n = 60) for 2 years. RESULTS: After 2 years, the DIMS group exhibited significantly smaller exophoric shifts in ocular alignment compared to the SV group at distance (1.5 ± 2.2 vs. 3.4 ± 3.1 PD, p = 0.001) and near (3.7 ± 4.1 vs. 6.8 ± 5.4 PD, p < 0.001). The DIMS group also demonstrated better preserved stereoacuity [values log10-transformed for statistical analysis but presented here in arcsec for clinical interpretability] (32 ± 12 vs. 48 ± 20 arcsec, p < 0.001), near point of convergence (7.2 ± 2.3 vs. 9.5 ± 3.6 cm, p = 0.001), and fusional vergence ranges (positive: 24 ± 8 vs. 18 ± 7 PD, p = 0.002; negative: 14 ± 5 vs. 11 ± 4 PD, p = 0.01) than the SV group at 2 years. The mean myopia progression over 2 years was significantly slower in the DIMS group than the SV group (-0.72 ± 0.32 vs. -1.25 ± 0.45 D, p < 0.001), with less axial elongation (0.41 ± 0.18 vs. 0.65 ± 0.25 mm, p < 0.001). The proportions of participants with clinically significant changes in ocular alignment (≥ 10 PD exophoria), stereoacuity (≥ 0.3 log arcsec loss), and convergence (≥ 4 cm recession in near point of convergence) were significantly lower in the DIMS group compared to the SV group (all p < 0.05). CONCLUSIONS: In myopic teenagers, DIMS spectacle lenses used for optical correction were associated with smaller changes in ocular alignment and binocular visual functions, and slowed myopia progression by 42% in terms of spherical equivalent refraction (SER). These results suggest that DIMS lenses may be effective in controlling both refractive progression and certain binocular function changes in adolescents.