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The aim of this study is to investigate if baseline relative peripheral refraction (RPR) influences the myopia control effects in Chinese myopic children wearing Defocus Incorporated Multiple Segments (DIMS) lenses. Peripheral refraction at 10°, 20°, and 30° nasal (10 N, 20 N, 30 N) and temporal (10 T, 20 T, 30 T) retina were measured at six-month intervals for children who participated in a 2-year randomized controlled trial. The relationship between the baseline peripheral refractions and myopia progression and axial length changes were analysed. A total of 79 children and 81 children in the DIMS and single vision (SV) group were investigated, respectively. In the DIMS group, more baseline myopic RPR spherical equivalent (SE) was associated with more myopic progression (10 N: r = 0.36, p = 0.001; 20 N: r = 0.35, p = 0.001) and greater axial elongation (10 N: r = −0.34, p = 0.001; 20 N: r = −0.29, p = 0.006) after adjusting for co-factors. In the SV group, baseline RPR had association with only myopia progression (10 N: r = 0.37, p = 0.001; 20 N: r = 0.36, p = 0.001; 30 N: r = 0.35, p = 0.002) but not with axial elongation after Bonferroni correction (p > 0.008). No statistically significant relationship was found between temporal retina and myopia progression or axial elongation in both groups. Children with baseline myopic RPR had statistically significant more myopia progression (mean difference around −0.40 D) and more axial elongation (mean difference 0.15 mm) when compared with the children having baseline hyperopic RPR in the DIMS group but not in the SV group. In conclusion, the baseline RPR profile may not influence future myopia progression or axial elongation for the SV lens wearers. However, DIMS lenses slowed down myopia progression and was better in myopia control for the children with baseline hyperopic RPR than the children with myopic RPR. This may partially explain why myopia control effects vary among myopic children. Customised myopic defocus for individuals may optimise myopia control effects, and further research to determine the optimal dosage, with consideration of peripheral retinal profile, is warranted.

This study aimed to examine the effect of Defocus Incorporated Multiple Segments (DIMS) lenses on myopia progression and axial elongation in a clinical population. A retrospective study was conducted using clinical data from 489 and 156 patients aged 3 to 17 years old who were prescribed DIMS and single vision (SV) lenses, respectively at the Optometry Clinic of The Hong Kong Polytechnic University between July 2018 and August 2019. The study included patients with previous myopia control interventions. The changes in spherical equivalent refraction (SER) and axial length (AL) were measured and normalized to annual changes. The correlation between age at baseline and annual change in AL was also examined. The total change in SER and AL after DIMS were -0.94 ± 0.79D and 0.55 ± 0.40 mm, respectively with an average wearing period of 31.98 ± 9.97 months. The normalized annual changes in SER and AL in DIMS wearers were significantly smaller than those in SV wearers (DIMS; SER change vs. AL changes; -0.38 ± 0.32D vs. 0.22 ± 0.16 mm. SV; -0.45 ± 0.41D vs. 0.29 ± 0.20 mm,  < 0.05). Patients with a history of myopia control had greater myopia progression after wearing DIMS lenses. There was a significant negative correlation between age at baseline and annual change in AL (correlation coefficient,  = -0.61,  < 0.001), suggesting that myopia progression was faster in children with a younger age of onset. A small proportion of patients (2.7%) experienced a clinically significant axial shortening (total change in AL:-0.13 ± 0.07 mm) after wearing DIMS lenses more than 2 years. The study demonstrated that DIMS lenses could retard axial elongation, with the effect sustained with increased duration of lens wear. However, patients with previous myopia control experienced greater myopia progression after wearing DIMS lenses. The study also highlighted the potential for axial length shortening in a small proportion of patients after the DIMS lens wear. These findings underscore the importance of adherence to intervention in achieving optimal treatment efficacy. Further research is needed to understand the mechanisms underlying these effects and to optimize the use of optical interventions in myopia control.

This study evaluated the long-term myopia control effect and safety in children wearing Defocus Incorporated Multiple Segments (DIMS) spectacle lenses. Participants who completed the 2-year RCT were followed for a total of 6 years; their cycloplegic refractions and axial length were measured. Group 1 (n = 36) wore DIMS spectacles for 6 years; Group 2 (n = 14) wore DIMS lens for the first 3.5 years and SV spectacles afterwards; Group 3 (n = 22) wore SV spectacles in the first 2 years and switched to DIMS; Group 4 (n = 18) wore SV spectacles in the first 2 years, switched to DIMS for 1.5 years and then SV spectacles again. Group 1 showed no significant differences in myopia progression (− 0.52 ± 0.66 vs. − 0.40 ± 0.72D) and axial elongation (0.32 ± 0.26 vs. 0.28 ± 0.28 mm, both p  > 0.05) between the first and the later 3 years. In the last 2.5 years, DIMS lens groups (Groups 1 and 3) had less myopia progression and axial elongation than the single vision groups (Groups 2 and 4). There was no evidence of rebound after stopping the treatment. Post-wear visual functions in all groups were within norms. The results supported that DIMS lenses provided sustained myopia control without adverse effects over the 6-year study period. Trial registration: clinicaltrials.gov; NCT02206217.

AimTo determine if ‘Defocus Incorporated Multiple Segments’ (DIMS) spectacle lenses slow childhood myopia progression.MethodsA 2-year double-masked randomised controlled trial was carried out in 183 Chinese children aged 8–13 years, with myopia between −1.00 and −5.00 D and astigmatism ≤1.50 D. Children were randomly assigned to wear DIMS (n=93) or single vision (SV) spectacle lenses (n=90). DIMS lens incorporated multiple segments with myopic defocus of +3.50 D. Refractive error (cycloplegic autorefraction) and axial length were measured at 6month intervals.Results160 children completed the study, n=79 in the DIMS group and n=81 in the SV group. Average (SE) myopic progressions over 2 years were −0.41±0.06 D in the DIMS group and −0.85±0.08 D in the SV group. Mean (SE) axial elongation was 0.21±0.02 mm and 0.55±0.02 mm in the DIMS and SV groups, respectively. Myopia progressed 52% more slowly for children in the DIMS group compared with those in the SV group (mean difference −0.44±0.09 D, 95% CI −0.73 to −0.37, p<0.0001). Likewise, children in the DIMS group had less axial elongation by 62% than those in the SV group (mean difference 0.34±0.04 mm, 95% CI 0.22 to 0.37, p<0.0001). 21.5% children who wore DIMS lenses had no myopia progression over 2 years, but only 7.4% for those who wore SV lenses.ConclusionsDaily wear of the DIMS lens significantly retarded myopia progression and axial elongation in myopic children. Our results demonstrated simultaneous clear vision with constant myopic defocus can slow myopia progression.Trial registration number NCT02206217.

AimsTo determine myopia progression in children who continued to wear the defocus incorporated multiple segments (DIMS) lenses or switched from single vision (SV) to DIMS lenses for a 1-year period following a 2-year myopia control trial.Methods128 children participated in this study. The children who had worn DIMS lenses continued to wear DIMS lenses (DIMS group), and children who had worn SV lenses switched to wear DIMS lenses (Control-to-DIMS group). Cycloplegic spherical equivalent refraction (SER) and axial length (AL) were measured at 6-month interval. Historical controls were age matched to the DIMS group at 24 months and used for comparing the third-year changes.ResultsOver 3 years, SER and AL changes in the DIMS group (n=65) were −0.52±0.69D and 0.31±0.26 mm; these changes were not statistically significant over time (repeated measures analysis of variance, p>0.05).SER (−0.04±0. 38D) and AL (0.08±0.12 mm) changes in the Control-to-DIMS group (n=55) in the third year were less compared with the first (mean difference=0.45 ± 0.30D, 0.21±0.11 mm, p<0.001) and second (0.34±0.30D, 0.12±0.10 mm, p<0.001) years.Changes in SER and AL in both groups over that period were significantly less than in the historical control group (DIMS vs historical control: mean difference=−0.18±0.42D, p=0.012; 0.08±0.15 mm, p=0.001; Control-to-DIMS versus historical control: adjusted mean differences=−0.30±0.42D, p<0.001; 0.12±0.16 mm, p<0.001).ConclusionsMyopia control effect was sustained in the third year in children who had used the DIMS spectacles in the previous 2 years and was also shown in the children switching from SV to DIMS lenses.

Aims To determine if ‘Defocus Incorporated Soft Contact’ (DISC) lens wear slows childhood myopia progression. Methods A 2-year double-blind randomised controlled trial was carried out in 221 children aged 8–13 years, with myopia between −1.00 and −5.00 Dioptres (D) and astigmatism ≤1.00 D. Subjects were randomly assigned to the DISC (n=111) or single vision (SV; n=110) contact lens group. DISC lenses incorporated concentric rings, which provided an addition of +2.50 D, alternating with the normal distance correction. Refractive error (cycloplegic autorefraction) and axial length were measured at 6-month intervals. Differences between groups were analysed using unpaired t test. Results In total, 128 children completed the study, n=65 in the DISC group and n=63 in the SV group. Myopia progressed 25% more slowly for children in the DISC group compared with those in the control group (0.30 D/year; 95% CI −0.71 to −0.47 vs 0.4 D/year; 95% CI −0.93 to −0.65, p=0.031). Likewise, there was less axial elongation for children in the DISC versus SV groups (0.13 mm/year; 95% CI 0.20 to 0.31 vs 0.18 mm/year; 95% CI 0.30 to 0.43, p=0.009). Treatment effect correlated positively with DISC lens wearing time (r=0.342; p=0.005). Indeed, myopia in children who wore the DISC lenses for five or more hours/day progressed 46% (mean difference=−0.382 D, p=0.001; 95% CI −0.59 to −0.17) less than those in the SV group. Conclusions The daily wearing of DISC lens significantly slowed myopia progression and axial elongation in Hong Kong schoolchildren. The findings demonstrated that simultaneous clear vision with constant myopic defocus can retard myopia progression.

Myopia progression has been found to be worsening during the COVID-19 pandemic. It is important to control the rapid myopia progression in this period. To analyze the association of COVID-19-related lockdown measures with myopia progression in schoolchildren and to compare the performance of defocus incorporated multiple segments (DIMS) lens with that of single vision lens (SVL) treatment in reducing myopia progression. This cohort study involved an exploratory, prespecified, comparison of 2 independent longitudinal studies performed at the same institute beginning in 2019. Data from Hong Kong schoolchildren (aged 7-13 years) were gathered and analyzed. Data analysis was performed from June to July 2021. Schoolchildren in study 1 wore a DIMS lens for 18 months, and those in study 2 wore a SVL for 24 months. Cycloplegic spherical equivalent refraction and axial length were measured. Studies 1 and 2 started before the start of lockdown measures and continued throughout the lockdown. In both studies, periods of fewer and more COVID-19-related lockdown measures were identified. Because COVID-19 lockdown caused deviations from the visit schedule, myopia progression was normalized to 12-month change, which were compared between DIMS and SVL groups, also during the periods with less and more lockdown time. There were 115 participants (58 girls [50.4%]; mean [SD] age, 10.3 [1.5] years) in the DIMS group; their mean (SD) baseline refraction was -4.02 (1.46) D. There were 56 participants (29 girls [51.8%]; mean [SD] age, 10.8 [1.5] years) in the SVL group; their mean (SD) baseline refraction was -2.99 (1.06) D. After controlling for the covariates, DIMS treatment was significantly associated with 34% less axial elongation (0.19 mm [95% CI, 0.16 to 0.22 mm] vs 0.30 mm [95% CI, 0.25 to 0.35 mm]; P < .001) and 46% less myopic progression after 12 months (-0.31 D [95% CI, -0.39 to -0.23 D] vs -0.57 D [95% CI, -0.69 to -0.45 D]; P = .001) compared with SVL treatment. In both the DIMS and SVL groups, more lockdown time was associated with significantly more spherical equivalent refraction (-0.54 D [95% CI, -0.64 to 0.44 D] vs -0.34 D [95% CI, -0.44 to -0.25 D]; P = .01) and axial length (0.29 mm [95% CI, 0.25 to 0.32 mm] vs 0.20 mm [95% CI, 0.16 to 0.24 mm]; P = .001) compared with less lockdown time. No significant interaction between treatment type and lockdown time was observed. In this exploratory analysis, myopia progressed more rapidly in schoolchildren during the period when there were more COVID-19-related lockdown measures. However, optical treatment with DIMS was significantly associated with slower myopia progression compared with SVL treatment during the lockdown period.

This study examined the association between smart device usage and the 1-year change in refractive error among a representative sample of Hong Kong children and adolescents aged 8–14 years. A total of 1597 participants (49.9% male, mean age 10.9, SD 2.0) who completed both baseline (2017–2018) and 1-year follow-up (2018–2019) eye examinations were included in the present study. The non-cycloplegic auto-refractive error was measured and the average spherical equivalent refraction (SER) was analyzed. The participants also self-reported their smart device usage at baseline. Multivariate regression adjusted for age, sex, baseline SER, parents’ short-sightedness, BMI, time spent on moderate-to-vigorous physical activity (MVPA), and caregiver-reported socio-economic status showed that, compared with the reference group (<2 h per day on both smartphone and tablet usages), those who spent ≥2 h per day using a smartphone and <2 h per day using a tablet had a significantly negative shift in refractive error (1-year change in SER −0.25 vs. −0.09 D, p = 0.01) for the right eye, while the level of significance was marginal (1-year change −0.28 vs. −0.15 D, p = 0.055) for the left eye. To conclude, our data suggested spending at most 2 h per day on both smartphones and tablets.

Myopia is a common eye problem worldwide and is more prevalent in Oriental than in Caucasian populations. Subjects with high myopia are vulnerable to ocular complications later in life. The present study aimed to test linkage and association between high myopia and three candidate genes (MYOC, MMP2 and COL2A1) of myopia susceptibility by family-based association study approach. First, family-based association tests were performed on the COL2A1, MYOC and MMP2 genes in Han Chinese families in Hong Kong. All these genes are expressed in eyes and were selected based on their putative biological functions related to myopia. The COL2A1 gene is located at chromosome 12q13.11-q13.2 and encodes collagen type 2 alpha 1. Mutations in COL2A1 account for Sticker syndrome type I (STL1). Myopia is a common clinical feature of STL1. The myocilin gene (MYOC) is located at chromosome 1q24.3-q25.2 and encodes the myocilin protein. The MYOC polymorphisms were found associated with primary open angle glaucoma. Previous studies provided inconclusive evidence of association between the MYOC microsatellites (NGA17 and NGA19) and myopia in the Chinese population of Singapore. The MMP2 gene is at chromosome 16q13-q2l and encodes matrix metalloproteinase-2 enzyme, which breaks down extracellular matrix of sclera during myopia development. In total, 219 nuclear families (869 individuals) were included. Each family consisted of both parents and at least one high myopic offspring with ≤-5.00D of spherical power for both eyes. A comprehensive eye examination and venous blood collection were carried out for each subject. DNA was extracted from the blood sample and used for individual genotyping of genetic markers in the candidate genes. Family-based association analysis was performed for testing linkage/association between the candidate gene polymorphisms and high myopia. The results showed no definitive linkage/association of both COL2A1 and MMP2 genes with susceptibility to high myopia. Only significant linkage/association was shown between the polymorphisms (NGA17, NGA19, rs2421853 and rs235858) in the 3' flanking region of the MYOC gene and high myopia under one to three genetic models (additive, dominant and recessive models) even after correction of multiple comparisons by false discovery rate. Positive linkage and association of the two SNPs with high myopia is a novel finding, the evidence is particularly impressive for rs235858 (p=4.0×10-6 under an additive genetic model, and p=2.5×10-5 under dominant/recessive genetic models). Second, an exploratory study was conducted to assess the technical performance of TagMan genotyping assay for estimating SNP allele frequency in DNA pools. MYOC SNPs were investigated by this method in two DNA pools conveniently constructed from the parents and the myopic siblings. Preliminary results showed that this real-time PCR technique was rapid and gave reproducible estimates of relative allele frequencies, but its accuracy remains to be proved. In conclusion, MYOC was found associated with high myopia. The polymorphisms in the 3' flanking region of the MYOC gene are potential candidates of altering the risk for myopia and are worthy of further replication and functional study. The TaqMan method requires further studies before being used for estimating allele frequencies in DNA pools on a large scale.