RESUMEN
The global prevalence of myopia is increasing year by year, leading to many ocular health issues and social problems. In recent years, it has been confirmed that peripheral defocus is closely related to the occurrence and development of myopia. Alteration of the state of peripheral defocus can significantly influence the progression of myopia and emmetropization, but the exact mechanisms are still unclear. At present, there is no method that can completely control myopia. Nowadays, the main controlling methods, including orthokeratology lens, peripheral defocus lens and multi-focal soft lens, have been confirmed to be closely related to peripheral defocus. In this paper, we will review and summarize the development and effect of these peripheral defocus relating control methods. In addition, the researches on the related mechanisms of peripheral retinal defocus and myopia prevention and control at home and abroad are reviewed, as well as the potential mechanisms of peripheral defocus, with a view to further improving the controlling effects of existing methods, developing new prevention and control methods and reducing the incidence and progression of myopia.
RESUMEN
AIM: To investigate the effect of peripheral defocus spectacles and orthokeratology lenses on the control of axial length in children and adolescents with myopia.METHODS: Prospective study. A total of 71 cases(134 eyes)of children and adolescents with myopia who visited the Second Hospital of Longyan from June 2019 to June 2021 were selected. They were fitted with peripheral defocus spectacles for 12mo and then switched to orthokeratology lenses. The growth of axial length was observed at 3, 6, and 12mo after wearing peripheral defocus spectacles and orthokeratology lenses.RESULTS: The median axial length growth after wearing peripheral defocus spectacles and orthokeratology lenses for 12mo was 0.35 and 0.14mm, respectively. The axial growth at 3, 6, and 12mo after wearing orthokeratology lenses was lower than those after wearing peripheral defocus spectacles(P<0.001), and the growth rate of axial length was significantly reduced. The patients were divided into a rapid progression group(axial growth ≥0.4 mm, 29 cases, 54 eyes)and a non-rapid progression group(axial growth <0.4mm, 42 cases, 80 eyes)according to the axial growth of peripheral defocus spectacles for 12mo. The median axial growth after wearing peripheral defocus spectacles for 12mo in the two groups was 0.70 and 0.24mm, respectively, while the median axial growth after wearing orthokeratology lenses was 0.31 and 0.09mm, respectively. The growth rate was reduced by 56% and 63% respectively in the two groups after wearing orthokeratology lens. The axial growth of cases wearing orthokeratology lenses for 12mo in the non-rapid progression group was lower than that in the rapid progression group, and it did not change with age or diopter. There was no significant difference among different ages and different diopters in the rapid progression group(P>0.05). In the non-rapid progression group, axial growth of cases aged 7-12 years was higher than those aged 13-16 years(P<0.05), but there was no significant difference among different diopters(P>0.05).CONCLUSION: Orthokeratology lens is more effective than peripheral defocus spectacles in controlling axial growth in children and adolescents with myopia, and the control effect of orthokeratology lens on rapid-progressing myopia is remarkable.
RESUMEN
Objective:To evaluate the effect of peripheral defocus soft contact lenses (PDSCLs), single-vision spectacles and single-vision contact lenses (SVCLs) on the progression of myopia in children and adolescents.Methods:A meta-analysis was conducted.To collect relevant studies on the myopia control effect of PDSCLs in children, English databases including PubMed, Medline, Embase and Cochrane library were searched with myopia, contact lens, children, adolescents, myopia progression, axial length, refractive error and relevant free English terms as key words.Chinese databases including CNKI, Wanfang and VIP were searched with corresponding Chinese phrases and relevant free Chinese terms as key words.Randomized controlled trials (RCTs) on the myopia control effect in children and adolescents, with PDSCLs wearer as experimental group and single-vision spectacles or SVCLs wearer as control group, were independently collected by two researchers.Quality of included studies was evaluated with the Cochrane tool to assess risk of bias for RCTs.Combined effects of change in refraction and axial length between experimental and control groups was calculated by weighted mean difference (WMD) and 95%confidence interval ( CI). The heterogeneity of included studies was evaluated by I2 statistic.The refraction and axial length of experimental and control groups were compared by Z test.Myopia control effect of different PDSCLs add powers was analyzed by subgroup analysis.The experimental data with add power ≤+ 2.00 D, low aberration and low depth of focus were assigned to low-medium add power subgroup, and the experimental data with add power >+ 2.00 D, high aberration and high depth of focus were assigned to high add power subgroup. Results:A total of 378 publications were retrieved.Finally, 10 high-quality RCTs and 14 groups of data were included in this meta-analysis.In these studies, 1 645 myopic children aged from 6 to 18 years were enrolled, including 808 cases in experimental group and 837 in control group.The follow-up ranged from 10 to 36 months.Among the 10 studies, there were two crossover trials without a washout period, so only the first intervention results were included.According to the meta-analysis, the change in refraction in experimental group was significantly less than that in control group (WMD=0.22 D, 95% CI: 0.15-0.30, Z=5.65; P<0.05). The change in axial elongation was significantly less in experimental group than control group (WMD=-0.10 mm, 95% CI: -0.12--0.09, Z=12.28; P<0.05). Subgroup analysis showed that the WMD of refraction change and axial elongation between experimental and control groups were 0.21 D (95% CI: 0.10-0.31) and-0.10 mm (95% CI: -0.13-0.08) in the low-medium add power subgroup, respectively, and were 0.26 D (95% CI: 0.13-0.38) and -0.13 mm (95% CI: -0.15--0.10) in the high add power subgroup, respectively. Conclusions:PDSCLs have better myopia control effect than single-vision spectacles and SVCLs in children and adolescents.When the add power is higher, PDSCLs can slow the progression of myopia more effectively.