Effect of Defocus Incorporated Multiple Segments (DIMS) spectacle lens wear on visual functions in myopic Chinese children

Purpose: To compare visual functions of myopic children who had worn either Defocus Incorporated Multiple Segment (DIMS) spectacle lenses or single vision spectacle lenses over two years. Methods: 160 Chinese myopic (-1D to -5D) children aged 8 to 13 years completed a randomized clinical trial; they wore either DIMS lenses (DIMS, n=79) or regular single-vision spectacles lenses (SV, n=81) in full-time mode for 2-years. Visual functions, including high- and low-contrast visual acuities (HCVA and LCVA) at distance and near, binocular functions, and accommodation, before, during and after 2-years of spectacle wear were assessed when both groups wore SV corrections. Changes of visual functions between the two groups and within groups were compared. Results: There were no statistically significant differences in the 2-year visual function changes between DIMS and SV groups (repeated measures ANOVA with group as factor, p>0.05). Statistically significant improvement in the best-corrected distance HCVA (p<0.001), and stereoacuity score (p<0.001) were found after DIMS lens wear over 2 years. Similar findings were observed after SV spectacle lens wear. For both the DIMS and SV groups, there were statistically significant reductions in accommodative lag, monocular and binocular amplitude of accommodation after two years (p<0.01), but not in the changes in distance LCVA, near HCVA, near LCVA nor phoria. Conclusions: Although changes in some visual functions were shown during 2-years of DIMS lens wear, similar changes were found with SV lens wear. Wear of DIMS spectacle lenses for 2 years does not adversely affect major visual functions when children return to SV corrections.