Effect of Defocus Incorporated Multiple Segments Spectacle Lens Wear on Visual Function in Myopic Chinese Children

Abstract

Purpose: To compare visual function of myopic children who had worn either defocus incorporated multiple segment (DIMS) spectacle lenses or single vision (SV) spectacle lenses over two years.

Methods: We included 160 Chinese myopic (-1 diopter [D] to -5 D) children aged 8 to 13 years in a randomized clinical trial; they wore either DIMS lenses (DIMS; n = 79) or regular SV spectacles lenses (n = 81) full time for 2 years. Visual function, including high-contrast visual acuity (VA) and low-contrast VA 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 function 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 analysis of variance with group as factor; P > 0.05). Statistically significant improvement in the best-corrected distance high-contrast VA (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 decreases in accommodative lag, monocular and binocular amplitude of accommodation after two years (P < 0.01), but not in the changes in distance low-contrast VA, near high-contrast VA, near low-contrast VA, or phoria.

Conclusions: Although changes in some visual function 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 function when children return to SV corrections.

Translational relevance: DIMS spectacle lenses did not cause any adverse effects on visual function.

Keywords: myopia; myopia control; myopic defocus; spectacle lens.

Figure.

Basic structure and design of the DIMS lens. Blue rays represent ray traces from the central (carrier) part of the lens and forming a clear image on retina [a] and the red rays show ray traces from the peripheral part of the lens, which contains the lenslets, forming an image that is simultaneously refracted by both the base part and lenslets [b]. If the target is at near and the eye does not accommodate, the image [c] or [d] will be formed on retina. The smallest Snellen chart in each image in the figure has the size of 5 arcmin which indicates VA 0.0 logMAR (20/20). Other two charts indicate VA +0.30 logMAR (20/40) and +0.50 logMAR (20/80), respectively. All images were generated using real ray tracing and wave optics calculations. Viewing an object through the central part of the lens produces a clear image with no ghosting. Viewing a target through the peripheral part of the lens leads to ghosting depending on the relative refractive error at the retina as described in [c] or [d].