PURPOSE: This study evaluated visual parameters and cortical activity after wearing myopia control spectacle lenses with defocus incorporated multiple segments (DIMS). METHODS: Myopic adults between 20 and 30 years of age were enrolled. The study consisted of (1) examination of visual parameters and (2) measurement of cortical responses, while wearing single vision lenses (SVL) and MiYOSMART (MS) lenses in counterbalanced order after a two-week adaptation period. Visual parameters tested were: high-contrast visual acuity (HCVA) and low-contrast visual acuity (LCVA), contrast sensitivity, heterophoria, near point of convergence (NPC), stereopsis, accommodative facility and the accommodative response. Cortical responses were assessed by visual evoked potentials (VEPs), recorded from 10 electrodes placed over the parieto-occipital area. RESULTS: MiYOSMART lenses produced slightly better HCVA than SVL (-0.25 vs. -0.21 logMAR, p = 0.02) and a larger accommodative response (MS 1.68 D
SVL 1.53 D, p <
0.002). No significant differences in LCVA, heterophoria, NPC, stereopsis or contrast sensitivity were observed. The latencies and amplitudes of the early and late components of the VEPs (C1, N1, P1, P2) did not differ significantly between lenses. CONCLUSIONS: This study found no clinically significant differences in visual parameters or visual cortex responses between SVL and MS lenses after 2 weeks of adaptation. These results confirm the absence of adverse visual effects from DIMS lenses for myopia control.