A randomized double-blind controlled study on the effects of wearing defocus incorporated multiple segments lenses on binocular visual function and visual quality

Objective  To evaluate the effects of wearing defocus incorporated multiple segments (DIMS) spectacle lenses on binocular visual function and visual quality in myopic children.

Methods  A randomized double-blind controlled study was conducted.A total of 176 children (352 eyes) with myopia aged 6 to 15 years were enrolled in the West China Hospital of Sichuan University from January 2021 to March 2022.They were randomly divided into DIMS group of 85 cases (170 eyes) and single-vision group of 91 cases (182 eyes) wearing DIMS and single-vision lenses, respectively, using the random number table method.A total of 151 cases (302 eyes) who completed follow-up visits were included in the analysis, including 72 cases (144 eyes) in the DIMS group and 79 cases (158 eyes) in the single-vision group.Before and after 6 and 12 months of lens wear, accommodation amplitude, binocular accommodative sensitivity, distance/near horizontal eye position, and accommodative convergence/accommodation (AC/A) of subjects were measured.Changes in visual function over the year were compared between the two groups.In addition, subjective contrast sensitivity (CS) was assessed at each follow-up visit to evaluate the effect of the lenses on visual quality.The study adhered to the Declaration of Helsinki.The study protocol was approved by the Ethics Committee of West China Hospital of Sichuan University (No.2020-06).Parents or legal guardians signed written informed consent before the child’s participation.

Results  There were significant differences in monocular accommodation amplitude and binocular accommodation sensitivity at different time points between before and after lens wear in both groups (Wald χ ² _time=84.435, 48.201; both P<0.001).In both groups, monocular accommodation amplitude was decreased and the biocular accommodation sensitivity was increased at 6 and 12 months after wearing glasses compared with baseline (all P<0.001).After 12 months of lens wear, the monocular accommodation amplitude decreased by 2.68 D (95% CI: 1.60-3.75 D) in DIMS group and 2.82 D (95% CI: 1.81-3.84 D) in single-vision group.There were statistically significant differences in distance and near horizontal eye position between the two groups at different time points before and after wearing glasses (Wald χ _time ²=10.398, 23.947; both P<0.01).In the DIMS group, after 12 months of wearing lenses, the distance horizontal eye position drifted outward by 0.68 ^△(95% CI: 0.06-1.25 ^△) compared to baseline, with a significant difference ( P<0.05).There was 1.67 ^△ (95% CI: 0.15-3.20 ^△) outward drift at near horizontal eye position in the DIMS group and 1.73 ^△ (95% CI: 0.49-2.96 ^△) outward drift in the single-vision group compared with baseline, with significant differences (both P<0.05).There were statistically significant differences in gradient AC/A values and calculated AC/A values between the two groups at different time points before and after wearing glasses (Wald χ _time ²=22.001, 13.411; both P<0.01).After 12 months of wearing glasses, the gradient AC/A values significantly decreased in both groups compared to respective baseline, and the calculated AC/A values in the single-vision group showed a significant decrease compared to baseline (all P<0.05).There were no significant difference in the monocular accommodation amplitude, binocular accommodation sensitivity, distance and near horizontal eye position, gradient AC/A values and calculated AC/A values between the two groups (Wald χ _group ²=2.385, 2.266, 2.070, 0.571, 0.578, 0.053; all P>0.05).There was no significant difference in the CS at 3, 6, 12, and 18 cpd spatial frequencies between the two groups at different time points before and after wearing lenses (Wald χ ² _group=1.104, 2.263, 1.861, 3.671; all P>0.05.Wald χ ² _time=2.260, 5.382, 2.573, 1.637; all P>0.05).

Conclusions  Visual function performance after wearing DIMS lenses is consistent with that after wearing single-vision lenses.Wearing DIMS lenses has no obvious negative effect on the long-term visual quality in children.

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