Full correction and Undercorrection of Myopia Evaluation Trial: design and baseline data of a randomized, controlled, double-blind trial

Advances in myopia prevention strategies for school-aged children: a comprehensive review

Myopia has significantly risen in East and Southeast Asia, and the pathological outcomes of this condition, such as myopic maculopathy and optic neuropathy linked to high myopia, have emerged as leading causes of irreversible vision loss. Addressing this issue requires strategies to reduce myopia prevalence and prevent progression to high myopia. Encouraging outdoor activities for schoolchildren and reducing near-work and screen time can effectively prevent myopia development, offering a safe intervention that promotes healthier habits. Several clinical approaches can be employed to decelerate myopia progression, such as administering low-dose atropine eye drops (0.05%), utilizing orthokeratology lenses, implementing soft contact lenses equipped with myopia control features, and incorporating spectacle lenses with aspherical lenslets. When choosing an appropriate strategy, factors such as age, ethnicity, and the rate of myopia progression should be considered. However, some treatments may encounter obstacles such as adverse side effects, high costs, complex procedures, or limited effectiveness. Presently, low-dose atropine (0.05%), soft contact lenses with myopia control features, and orthokeratology lenses appear as promising options for managing myopia. The measures mentioned above are not necessarily mutually exclusive, and researchers are increasingly exploring their combined effects. By advocating for a personalized approach based on individual risk factors and the unique needs of each child, this review aims to contribute to the development of targeted and effective myopia prevention strategies, thereby minimizing the impact of myopia and its related complications among school-aged children in affected regions.

Interventions for myopia control in children: a living systematic review and network meta-analysis

BACKGROUND

Myopia is a common refractive error, where elongation of the eyeball causes distant objects to appear blurred. The increasing prevalence of myopia is a growing global public health problem, in terms of rates of uncorrected refractive error and significantly, an increased risk of visual impairment due to myopia-related ocular morbidity. Since myopia is usually detected in children before 10 years of age and can progress rapidly, interventions to slow its progression need to be delivered in childhood.

OBJECTIVES

To assess the comparative efficacy of optical, pharmacological and environmental interventions for slowing myopia progression in children using network meta-analysis (NMA). To generate a relative ranking of myopia control interventions according to their efficacy. To produce a brief economic commentary, summarising the economic evaluations assessing myopia control interventions in children. To maintain the currency of the evidence using a living systematic review approach.  SEARCH METHODS: We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register), MEDLINE; Embase; and three trials registers. The search date was 26 February 2022.  SELECTION CRITERIA: We included randomised controlled trials (RCTs) of optical, pharmacological and environmental interventions for slowing myopia progression in children aged 18 years or younger. Critical outcomes were progression of myopia (defined as the difference in the change in spherical equivalent refraction (SER, dioptres (D)) and axial length (mm) in the intervention and control groups at one year or longer) and difference in the change in SER and axial length following cessation of treatment ('rebound').  DATA COLLECTION AND ANALYSIS: We followed standard Cochrane methods. We assessed bias using RoB 2 for parallel RCTs. We rated the certainty of evidence using the GRADE approach for the outcomes: change in SER and axial length at one and two years. Most comparisons were with inactive controls.

MAIN RESULTS

We included 64 studies that randomised 11,617 children, aged 4 to 18 years. Studies were mostly conducted in China or other Asian countries (39 studies, 60.9%) and North America (13 studies, 20.3%). Fifty-seven studies (89%) compared myopia control interventions (multifocal spectacles, peripheral plus spectacles (PPSL), undercorrected single vision spectacles (SVLs), multifocal soft contact lenses (MFSCL), orthokeratology, rigid gas-permeable contact lenses (RGP); or pharmacological interventions (including high- (HDA), moderate- (MDA) and low-dose (LDA) atropine, pirenzipine or 7-methylxanthine) against an inactive control. Study duration was 12 to 36 months. The overall certainty of the evidence ranged from very low to moderate. Since the networks in the NMA were poorly connected, most estimates versus control were as, or more, imprecise than the corresponding direct estimates. Consequently, we mostly report estimates based on direct (pairwise) comparisons below. At one year, in 38 studies (6525 participants analysed), the median change in SER for controls was -0.65 D. The following interventions may reduce SER progression compared to controls: HDA (mean difference (MD) 0.90 D, 95% confidence interval (CI) 0.62 to 1.18), MDA (MD 0.65 D, 95% CI 0.27 to 1.03), LDA (MD 0.38 D, 95% CI 0.10 to 0.66), pirenzipine (MD 0.32 D, 95% CI 0.15 to 0.49), MFSCL (MD 0.26 D, 95% CI 0.17 to 0.35), PPSLs (MD 0.51 D, 95% CI 0.19 to 0.82), and multifocal spectacles (MD 0.14 D, 95% CI 0.08 to 0.21). By contrast, there was little or no evidence that RGP (MD 0.02 D, 95% CI -0.05 to 0.10), 7-methylxanthine (MD 0.07 D, 95% CI -0.09 to 0.24) or undercorrected SVLs (MD -0.15 D, 95% CI -0.29 to 0.00) reduce progression.  At two years, in 26 studies (4949 participants), the median change in SER for controls was -1.02 D. The following interventions may reduce SER progression compared to controls: HDA (MD 1.26 D, 95% CI 1.17 to 1.36), MDA (MD 0.45 D, 95% CI 0.08 to 0.83), LDA (MD 0.24 D, 95% CI 0.17 to 0.31), pirenzipine (MD 0.41 D, 95% CI 0.13 to 0.69), MFSCL (MD 0.30 D, 95% CI 0.19 to 0.41), and multifocal spectacles  (MD 0.19 D, 95% CI 0.08 to 0.30). PPSLs (MD 0.34 D, 95% CI -0.08 to 0.76) may also reduce progression, but the results were inconsistent. For RGP, one study found a benefit and another found no difference with control. We found no difference in SER change for undercorrected SVLs (MD 0.02 D, 95% CI -0.05 to 0.09). At one year, in 36 studies (6263 participants), the median change in axial length for controls was 0.31 mm. The following interventions may reduce axial elongation compared to controls: HDA (MD -0.33 mm, 95% CI -0.35 to 0.30), MDA (MD -0.28 mm, 95% CI -0.38 to -0.17), LDA (MD -0.13 mm, 95% CI -0.21 to -0.05), orthokeratology (MD -0.19 mm, 95% CI -0.23 to -0.15), MFSCL (MD -0.11 mm, 95% CI -0.13 to -0.09), pirenzipine (MD -0.10 mm, 95% CI -0.18 to -0.02), PPSLs (MD -0.13 mm, 95% CI -0.24 to -0.03), and multifocal spectacles (MD -0.06 mm, 95% CI -0.09 to -0.04). We found little or no evidence that RGP (MD 0.02 mm, 95% CI -0.05 to 0.10), 7-methylxanthine (MD 0.03 mm, 95% CI -0.10 to 0.03) or undercorrected SVLs (MD 0.05 mm, 95% CI -0.01 to 0.11) reduce axial length. At two years, in 21 studies (4169 participants), the median change in axial length for controls was 0.56 mm. The following interventions may reduce axial elongation compared to controls: HDA (MD -0.47mm, 95% CI -0.61 to -0.34), MDA (MD -0.33 mm, 95% CI -0.46 to -0.20), orthokeratology (MD -0.28 mm, (95% CI -0.38 to -0.19), LDA (MD -0.16 mm, 95% CI -0.20 to  -0.12), MFSCL (MD -0.15 mm, 95% CI -0.19 to -0.12), and multifocal spectacles (MD -0.07 mm, 95% CI -0.12 to -0.03). PPSL may reduce progression (MD -0.20 mm, 95% CI -0.45 to 0.05) but results were inconsistent. We found little or no evidence that undercorrected SVLs (MD -0.01 mm, 95% CI -0.06 to 0.03) or RGP (MD 0.03 mm, 95% CI -0.05 to 0.12) reduce axial length. There was inconclusive evidence on whether treatment cessation increases myopia progression. Adverse events and treatment adherence were not consistently reported, and only one study reported quality of life. No studies reported environmental interventions reporting progression in children with myopia, and no economic evaluations assessed interventions for myopia control in children.

AUTHORS' CONCLUSIONS

Studies mostly compared pharmacological and optical treatments to slow the progression of myopia with an inactive comparator. Effects at one year provided evidence that these interventions may slow refractive change and reduce axial elongation, although results were often heterogeneous. A smaller body of evidence is available at two or three years, and uncertainty remains about the sustained effect of these interventions. Longer-term and better-quality studies comparing myopia control interventions used alone or in combination are needed, and improved methods for monitoring and reporting adverse effects.

Early Age of the First Myopic Spectacle Prescription, as an Indicator of Early Onset of Myopia, Is a Risk Factor for High Myopia in Adulthood

Purpose

The present study investigated the risk factors for high myopia in adulthood, with a focus on the age at which children wore their first spectacles.

Methods

Adults aged between 20 and 45 years were invited to complete a questionnaire about age, sex, current refractive error, high myopia in parents, early onset of myopia presented by the age of the first myopic spectacle prescription, refractive power of the first spectacles, and life habits at different educational stages. The associations between these factors and high myopia in adulthood were then evaluated and analyzed.

Results

In total, 331 participants were enrolled. Their average refractive error was −4.03 diopters, and high myopia was noted in 27.5% of the study participants. Only 3.3% of participants had fathers with high myopia, while 6.0% had mothers with high myopia. The participants received their first myopic spectacle prescription at a mean age of 13.35 years, with a mean refractive error of −1.63 diopters. The significant risk factors for developing high myopia in adult life were earlier age of the first spectacles prescribed (p < 0.001), higher refractive power of the first spectacles (p < 0.001), mother with high myopia (p=0.015), and after-school class attendance in senior high school (p=0.018). Those who wore their first spectacles at <9 years of age were more predisposed to high myopia than those who did so at ≧13 years, with an odds ratio of 24.9.

Conclusion

The present study shows that earlier onset of myopia, which is presented by the age of the first myopic spectacle prescription, higher myopic refraction of the first spectacles, mothers with high myopia, and after-school class attendance in senior high school are risk factors for high myopia in adulthood. It suggests that delaying the onset of myopia in children is important for the prevention of high myopia in later life.

Under-correction or full correction of myopia? A meta-analysis

PURPOSE

To compare the effect of full-correction versus under-correction on myopia progression.

METHODS

A literature search was performed in PubMed, Scopus, Science Direct, Ovid, Web of Science and Cochrane library. Methodological quality assessment of the literature was evaluated according to the Critical Appraisal Skills Program. Statistical analysis was performed using Comprehensive Meta-Analysis (version 2, Biostat Inc., USA).

RESULTS

The present meta-analysis included six studies (two randomized controlled trials [RCTs] and four non-RCTs) with 695 subjects (full-correction group, n=371; under-correction group, n=324) aged 6 to 33 years. Using cycloplegic refraction, the pooled difference in mean of myopia progression was - 0.179 D [lower and higher limits: -0.383, 0.025], which was higher but not in full correction group as compared to under correction group (p=0.085). Regarding studies using non-cycloplegic subjective refraction according to maximum plus for maximum visual acuity, the pooled difference in myopia progression was 0.128 D [lower and higher limits: -0.057, 0.312] higher in under-correction group compared with full-correction group (p=0.175). Although, difference in myopia progression did not reach significant level in either cycloplegic or non-cycloplegic refraction.

CONCLUSIONS

Our findings suggest that, myopic eyes which are fully corrected with non-cycloplegic refraction with maximum plus sphere, are less prone to myopia progression, in comparison to those which were under corrected. However, regarding cycloplegic refraction, further studies are needed to better understand these trends.

Interventions to slow progression of myopia in children

BACKGROUND

Nearsightedness (myopia) causes blurry vision when one is looking at distant objects. Interventions to slow the progression of myopia in children include multifocal spectacles, contact lenses, and pharmaceutical agents.

OBJECTIVES

To assess the effects of interventions, including spectacles, contact lenses, and pharmaceutical agents in slowing myopia progression in children.

SEARCH METHODS

We searched CENTRAL; Ovid MEDLINE; Embase.com; PubMed; the LILACS Database; and two trial registrations up to February 2018. A top up search was done in February 2019.

SELECTION CRITERIA

We included randomized controlled trials (RCTs). We excluded studies when most participants were older than 18 years at baseline. We also excluded studies when participants had less than -0.25 diopters (D) spherical equivalent myopia.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods.

MAIN RESULTS

We included 41 studies (6772 participants). Twenty-one studies contributed data to at least one meta-analysis. Interventions included spectacles, contact lenses, pharmaceutical agents, and combination treatments. Most studies were conducted in Asia or in the United States. Except one, all studies included children 18 years or younger. Many studies were at high risk of performance and attrition bias. Spectacle lenses: undercorrection of myopia increased myopia progression slightly in two studies; children whose vision was undercorrected progressed on average -0.15 D (95% confidence interval [CI] -0.29 to 0.00; n = 142; low-certainty evidence) more than those wearing fully corrected single vision lenses (SVLs). In one study, axial length increased 0.05 mm (95% CI -0.01 to 0.11) more in the undercorrected group than in the fully corrected group (n = 94; low-certainty evidence). Multifocal lenses (bifocal spectacles or progressive addition lenses) yielded small effect in slowing myopia progression; children wearing multifocal lenses progressed on average 0.14 D (95% CI 0.08 to 0.21; n = 1463; moderate-certainty evidence) less than children wearing SVLs. In four studies, axial elongation was less for multifocal lens wearers than for SVL wearers (-0.06 mm, 95% CI -0.09 to -0.04; n = 896; moderate-certainty evidence). Three studies evaluating different peripheral plus spectacle lenses versus SVLs reported inconsistent results for refractive error and axial length outcomes (n = 597; low-certainty evidence). Contact lenses: there may be little or no difference between vision of children wearing bifocal soft contact lenses (SCLs) and children wearing single vision SCLs (mean difference (MD) 0.20D, 95% CI -0.06 to 0.47; n = 300; low-certainty evidence). Axial elongation was less for bifocal SCL wearers than for single vision SCL wearers (MD -0.11 mm, 95% CI -0.14 to -0.08; n = 300; low-certainty evidence). Two studies investigating rigid gas permeable contact lenses (RGPCLs) showed inconsistent results in myopia progression; these two studies also found no evidence of difference in axial elongation (MD 0.02mm, 95% CI -0.05 to 0.10; n = 415; very low-certainty evidence). Orthokeratology contact lenses were more effective than SVLs in slowing axial elongation (MD -0.28 mm, 95% CI -0.38 to -0.19; n = 106; moderate-certainty evidence). Two studies comparing spherical aberration SCLs with single vision SCLs reported no difference in myopia progression nor in axial length (n = 209; low-certainty evidence). Pharmaceutical agents: at one year, children receiving atropine eye drops (3 studies; n = 629), pirenzepine gel (2 studies; n = 326), or cyclopentolate eye drops (1 study; n = 64) showed significantly less myopic progression compared with children receiving placebo: MD 1.00 D (95% CI 0.93 to 1.07), 0.31 D (95% CI 0.17 to 0.44), and 0.34 (95% CI 0.08 to 0.60), respectively (moderate-certainty evidence). Axial elongation was less for children treated with atropine (MD -0.35 mm, 95% CI -0.38 to -0.31; n = 502) and pirenzepine (MD -0.13 mm, 95% CI -0.14 to -0.12; n = 326) than for those treated with placebo (moderate-certainty evidence) in two studies. Another study showed favorable results for three different doses of atropine eye drops compared with tropicamide eye drops (MD 0.78 D, 95% CI 0.49 to 1.07 for 0.1% atropine; MD 0.81 D, 95% CI 0.57 to 1.05 for 0.25% atropine; and MD 1.01 D, 95% CI 0.74 to 1.28 for 0.5% atropine; n = 196; low-certainty evidence) but did not report axial length. Systemic 7-methylxanthine had little to no effect on myopic progression (MD 0.07 D, 95% CI -0.09 to 0.24) nor on axial elongation (MD -0.03 mm, 95% CI -0.10 to 0.03) compared with placebo in one study (n = 77; moderate-certainty evidence). One study did not find slowed myopia progression when comparing timolol eye drops with no drops (MD -0.05 D, 95% CI -0.21 to 0.11; n = 95; low-certainty evidence). Combinations of interventions: two studies found that children treated with atropine plus multifocal spectacles progressed 0.78 D (95% CI 0.54 to 1.02) less than children treated with placebo plus SVLs (n = 191; moderate-certainty evidence). One study reported -0.37 mm (95% CI -0.47 to -0.27) axial elongation for atropine and multifocal spectacles when compared with placebo plus SVLs (n = 127; moderate-certainty evidence). Compared with children treated with cyclopentolate plus SVLs, those treated with atropine plus multifocal spectacles progressed 0.36 D less (95% CI 0.11 to 0.61; n = 64; moderate-certainty evidence). Bifocal spectacles showed small or negligible effect compared with SVLs plus timolol drops in one study (MD 0.19 D, 95% CI 0.06 to 0.32; n = 97; moderate-certainty evidence). One study comparing tropicamide plus bifocal spectacles versus SVLs reported no statistically significant differences between groups without quantitative results. No serious adverse events were reported across all interventions. Participants receiving antimuscarinic topical medications were more likely to experience accommodation difficulties (Risk Ratio [RR] 9.05, 95% CI 4.09 to 20.01) and papillae and follicles (RR 3.22, 95% CI 2.11 to 4.90) than participants receiving placebo (n=387; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

Antimuscarinic topical medication is effective in slowing myopia progression in children. Multifocal lenses, either spectacles or contact lenses, may also confer a small benefit. Orthokeratology contact lenses, although not intended to modify refractive error, were more effective than SVLs in slowing axial elongation. We found only low or very low-certainty evidence to support RGPCLs and sperical aberration SCLs.

IMI - Clinical Myopia Control Trials and Instrumentation Report

The evidence-basis based on existing myopia control trials along with the supporting academic literature were reviewed; this informed recommendations on the outcomes suggested from clinical trials aimed at slowing myopia progression to show the effectiveness of treatments and the impact on patients. These outcomes were classified as primary (refractive error and/or axial length), secondary (patient reported outcomes and treatment compliance), and exploratory (peripheral refraction, accommodative changes, ocular alignment, pupil size, outdoor activity/lighting levels, anterior and posterior segment imaging, and tissue biomechanics). The currently available instrumentation, which the literature has shown to best achieve the primary and secondary outcomes, was reviewed and critiqued. Issues relating to study design and patient selection were also identified. These findings and consensus from the International Myopia Institute members led to final recommendations to inform future instrumentation development and to guide clinical trial protocols.

Vision screening for correctable visual acuity deficits in school-age children and adolescents

BACKGROUND

Although the benefits of vision screening seem intuitive, the value of such programmes in junior and senior schools has been questioned. In addition there exists a lack of clarity regarding the optimum age for screening and frequency at which to carry out screening.

OBJECTIVES

To evaluate the effectiveness of vision screening programmes carried out in schools to reduce the prevalence of correctable visual acuity deficits due to refractive error in school-age children.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 4); Ovid MEDLINE; Ovid Embase; the ISRCTN registry; ClinicalTrials.gov and the ICTRP. The date of the search was 3 May 2017.

SELECTION CRITERIA

We included randomised controlled trials (RCTs), including cluster-randomised trials, that compared vision screening with no vision screening, or compared interventions to improve uptake of spectacles or efficiency of vision screening.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened search results and extracted data. Our pre-specified primary outcome was uncorrected, or suboptimally corrected, visual acuity deficit due to refractive error six months after screening. Pre-specified secondary outcomes included visual acuity deficit due to refractive error more than six months after screening, visual acuity deficit due to causes other than refractive error, spectacle wearing, quality of life, costs, and adverse effects. We graded the certainty of the evidence using GRADE.

MAIN RESULTS

We identified seven relevant studies. Five of these studies were conducted in China with one study in India and one in Tanzania. A total of 9858 children aged between 10 and 18 years were randomised in these studies, 8240 of whom (84%) were followed up between one and eight months after screening. Overall we judged the studies to be at low risk of bias. None of these studies compared vision screening for correctable visual acuity deficits with not screening.Two studies compared vision screening with the provision of free spectacles versus vision screening with no provision of free spectacles (prescription only). These studies provide high-certainty evidence that vision screening with provision of free spectacles results in a higher proportion of children wearing spectacles than if vision screening is accompanied by provision of a prescription only (risk ratio (RR) 1.60, 95% confidence interval (CI) 1.34 to 1.90; 1092 participants). The studies suggest that if approximately 250 per 1000 children given vision screening plus prescription only are wearing spectacles at follow-up (three to six months) then 400 per 1000 (335 to 475) children would be wearing spectacles after vision screening and provision of free spectacles. Low-certainty evidence suggested better educational attainment in children in the free spectacles group (adjusted difference 0.11 in standardised mathematics score, 95% CI 0.01 to 0.21, 1 study, 2289 participants). Costs were reported in one study in Tanzania in 2008 and indicated a relatively low cost of screening and spectacle provision (low-certainty evidence). There was no evidence of any important effect of provision of free spectacles on uncorrected visual acuity (mean difference -0.02 logMAR (95% CI adjusted for clustering -0.04 to 0.01) between the groups at follow-up (moderate-certainty evidence). Other pre-specified outcomes of this review were not reported.Two studies explored the effect of an educational intervention in addition to vision screening on spectacle wear. There was moderate-certainty evidence of little apparent effect of the education interventions investigated in these studies in addition to vision screening, compared to vision screening alone for spectacle wearing (RR 1.11, 95% CI 0.95 to 1.31, 1 study, 3177 participants) or related outcome spectacle purchase (odds ratio (OR) 0.84, 95% CI 0.55 to 1.31, 1 study, 4448 participants). Other pre-specified outcomes of this review were not reported.Three studies compared vision screening with ready-made spectacles versus vision screening with custom-made spectacles. These studies provide moderate-certainty evidence of no clinically meaningful differences between the two types of spectacles. In one study, mean logMAR acuity in better and worse eye was similar between groups: mean difference (MD) better eye 0.03 logMAR, 95% CI 0.01 to 0.05; 414 participants; MD worse eye 0.06 logMAR, 95% CI 0.04 to 0.08; 414 participants). There was high-certainty evidence of no important difference in spectacle wearing (RR 0.98, 95% CI 0.91 to 1.05; 1203 participants) between the two groups and moderate-certainty evidence of no important difference in quality of life between the two groups (the mean quality-of-life score measured using the National Eye Institute Refractive Error Quality of Life scale 42 was 1.42 better (1.04 worse to 3.90 better) in children with ready-made spectacles (1 study of 188 participants). Although none of the studies reported on costs directly, ready-made spectacles are cheaper and may represent considerable cost-savings for vision screening programmes in lower income settings. There was low-certainty evidence of no important difference in adverse effects between the two groups. Adverse effects were reported in one study and were similar between groups. These included blurred vision, distorted vision, headache, disorientation, dizziness, eyestrain and nausea.

AUTHORS' CONCLUSIONS

Vision screening plus provision of free spectacles improves the number of children who have and wear the spectacles they need compared with providing a prescription only. This may lead to better educational outcomes. Health education interventions, as currently devised and tested, do not appear to improve spectacle wearing in children. In lower-income settings, ready-made spectacles may provide a useful alternative to expensive custom-made spectacles.

Refractive error change and vision improvement in moderate to severe hyperopic amblyopia after spectacle correction: Restarting the emmetropization process?

Purpose

The aims of the study were to develop guidelines for prescribing spectacles for patients with moderate to severe hyperopic amblyopia and to demonstrate how emmetropization progresses.

Methods

Children with hyperopic amblyopia who had a spherical equivalent of ≥ +4.0 diopters (D) or more were included, while those who had astigmatism of > 2.0 D or anisometropia of > 2.0 D were excluded. The patients were divided into a full correction group and an under-correction group according to the amount of hyperopia correction applied. The under-correction group was further subdivided into a fixed under-correction group and a post-cycloplegic refraction (PCR) under-correction group. The duration of amblyopia treatment and changes in initial hyperopia were compared between the groups.

Results

In total, 76 eyes of 38 patients were analyzed in this study. The full correction group and under-correction group were subjected to 5.5 months and 5.9 months of amblyopia treatment, respectively (P = 0.570). However, the PCR under-correction group showed more rapid improvement (2.9 months; P = 0.001). In the under-correction group, initial hyperopia was decreased by -0.28 D and -0.49 D at 6 months and 12 months, respectively, after initial cycloplegic refraction. Moreover, the amount of hyperopia under-correction was correlated with the amount of hyperopia reduction (P = 0.010).

Conclusion

The under-correction of moderate to severe hyperopic amblyopia has beneficial effects for treating amblyopia and activating emmetropization. PCR under-correction can more rapidly improve visual acuity, while both fixed under-correction and PCR under-correction can induce emmetropization and effectively reduce initial hyperopia.

Bio-environmental factors associated with myopia: An updated review

Experimental studies in animals, as well as observational and intervention studies in humans, seem to support the premise that the development of juvenile myopia is promoted by a combination of the effect of genetic and environmental factors, with a complex interaction between them. The very rapid increase in myopia rates in some parts of the world, such as Southeast Asia, supports a significant environmental effect. Several lines of evidence suggest that humans might respond to various external factors, such as increased activity in near vision, increased educational pressure, decreased exposure to sunlight outdoors, dietary changes (including increased intake of carbohydrates), as well as low light levels indoors. All these factors could be associated with a higher prevalence of myopia.

Efficacy of Chinese eye exercises on reducing accommodative lag in school-aged children: a randomized controlled trial

Purpose

To evaluate the efficacy of Chinese eye exercises on reducing accommodative lag in children by a randomized, double-blinded controlled trial.

Methods

A total of 190 children aged 10 to 14 years with emmetropia to moderate myopia were included. They were randomly allocated to three groups: standard Chinese eye exercises group (trained for eye exercises by doctors of traditional Chinese medicine); sham point eye exercises group (instructed to massage on non-acupoints); and eyes closed group (asked to close their eyes without massage). Primary outcome was change in accommodative lag immediately after intervention. Secondary outcomes included changes in corrected near and distant visual acuity, and visual discomfort score.

Results

Children in the standard Chinese eye exercises group had significantly greater alleviation of accommodative lag (-0.10D) than those in sham point eye exercises group (-0.03D) and eyes closed group (0.07D) (P = 0.04). The proportion of children with alleviation of accommodative lag was significantly higher in the standard Chinese eye exercises group (54.0%) than in the sham point eye exercises group (32.8%) and the eyes closed group (34.9%) (P = 0.03). No significant differences were found in secondary outcomes.

Conclusion

Chinese eye exercises as performed daily in primary and middle schools in China have statistically but probably clinically insignificant effect in reducing accommodative lag of school-aged children in the short-term. Considering the higher amounts of near work load of Chinese children, the efficacy of eye exercises may be insufficient in preventing myopia progression in the long-term.

Trial Registration

ClinicalTrials.gov NCT01756287

Under-correction of human myopia--is it myopigenic?: a retrospective analysis of clinical refraction data

PURPOSE

To investigate retrospectively, based on routine clinical records in an optometric office, the effect of refractive under-correction of the myopic spectacle prescription on myopic progression in children and young adults.

METHODS

Patient records of children and young-adult myopes in a private optometric practice in Glendale, Arizona, USA, were initially reviewed to identify those that met the criteria. Information collected from the patient records included: age, gender, the dates and number of their visits (more than one visit was required for use of the data), final prescription, and non-cycloplegic subjective refraction. For each patient visit, the difference in spherical equivalent (SE) between the subjective refraction for maximum visual acuity and the final prescription was calculated for both the left and right eyes. Myopia progression was defined as the difference in SE between the final subjective refraction of the previous visit and that of the subsequent visit. Based on the study criteria, a total of 275 patient visits were obtained from the data collected in 76 patients.

RESULTS

A significant positive correlation was found between the magnitude of under-correction of the refractive error and myopic progression (r=0.301, p<0.01); that is, the greater the under-correction, the greater the myopic progression. In addition, there was a significant positive correlation between myopia progression and subjective refraction (r=0.166, p=0.006); that is, the greater the degree of myopia, the greater the effect of under-correction. However, there was no significant correlation between myopia progression and either age (r=-0.11, p=0.86) or gender (r=-0.82, p=0.17).

CONCLUSION

Under-correction of myopia produced a small but progressively greater degree of myopic progression than did full correction. The present finding is consistent with earlier clinical trials and modeling of human myopia.