Impact of Wearing Defocus Incorporated Multiple Segments Spectacle Lenses for 12 Months on Accommodation and...

Spectacle lens design for myopia control incorporates either lenslet or diffusion technology to slow down the eye growth, which may impact the binocular vision functions of a myopic child. This study aimed to investigate the changes in accommodation and binocular functions in myopic children over 12 months wear of myopia control spectacle lenses.

21 myopic children aged 7-12 years were prescribed with Defocus Incorporated Multiple Segments (DIMS) lenses and assessed at baseline, 1, 3, 6, 9, and 12 months. The parameters measured were refractive error, axial length (AL), visual acuity (VA), accommodative lag (LA), amplitude of accommodation (AA), negative/positive relative accommodation (NRA/PRA), stereoacuity, near point of convergence (NPC), phoria, negative/positive fusional vergence (NFV/PFV), and accommodation convergence per accommodation ratio (AC/A).

Mean spherical equivalent (SE) and AL increase from -2.90 ± 1.15 D and 24.51 ± 0.99 mm to -3.19 ± 1.25 D and 24.60 ± 0.97 mm at 12 months respectively. Visual acuity (VA) significantly improved (p < 0.001) in both high-contrast and low-contrast conditions at distance and near. Regarding accommodation and binocular functions, significant improvements were observed in lag of accommodation (LA), stereoacuity and gradient AC/A ratio (p < 0.001). The NPC reduced slightly but was still within normal limits. Distance and near phoria shifted toward esophoria with changes less than 1 PD. Additionally, distance NFV and near PFV recovery points increased significantly.

This study demonstrated insignificant changes in accommodation and binocular functions in myopic children after 12 months of wearing DIMS lenses. However, the absence of a control group limits causal interpretation, as observed changes may be influenced by natural development, repeated testing, or regression to the mean. Further research with controlled designs is warranted to clarify these effects.