Myopia in teenagers. An eight-year follow-up study on myopia progression and risk factors

Temporal effects of an original myopia song on school children's myopia and awareness: a 3-year prospective study

CLINICAL RELEVANCE

Raising children's myopia prevention awareness and behaviour tends to exhibits a protective effect against myopia among schoolchildren.

BACKGROUND

To investigate the effect of an original myopia song in raising school children's awareness of healthier eye use behaviour and on myopia prevention.

METHODS

In this prospective randomised control study, two groups of students from one primary schools in Jiangxi, China, were enrolled and monitored from grade 3 to grade 6 (2016-2019). The primary outcome was the change in axial length (AL) after the intervention. Secondary outcomes included changes in spherical equivalent refraction (SER), near work and outdoor time, corrected near and distant visual acuity, visual discomfort score (VDS) and accommodative lag.

RESULTS

Four hundred students (193 females, 48.25%) aged 9.3 (range 8-10) years with emmetropia to moderate myopia were enrolled. Children in the myopia song group had a significantly shorter AL and less myopic refractive change than those in the control group (p = 0.04 and 0.02, respectively). Compared with the control group, children in the myopia song group spent less time on near work and more time outdoors (p = 0.04 and 0.04, respectively). At the final follow-up, the proportion of children with myopia was significantly lower in the myopia song group (30.5%) than in the control group (41%) (p = 0.03). No significant differences were found for the secondary outcomes, including corrected near and distant visual acuity, VDS and accommodative lag.

CONCLUSIONS

An original myopia song performed twice daily in primary schools appeared to have a modest effect on myopia control among school-aged children by changing their lifestyles in the long term.

Interventions to increase time spent outdoors for preventing incidence and progression of myopia in children

BACKGROUND

Myopia or nearsightedness is a type of refractive error. It causes people to see near objects clearly but distant objects as blurred. Good vision can be obtained if the refractive error is corrected properly but, where this is not possible, impaired vision will remain. The remaining myopia imposes a considerable personal and societal burden. In addition, the progression of myopia is more likely to be accompanied by other ocular diseases such as cataract, glaucoma and retinal detachment. Myopia has emerged as a significant global public health problem in recent years. The World Health Organization (WHO) reported uncorrected or undercorrected myopia to be a major cause of visual impairment worldwide. From both an individual and social perspective, it is important to prevent the onset of myopia and slow down its progression. Observational studies have shown that children who spend more time outdoors have a lower incidence of myopia. Several other non-Cochrane systematic reviews have focused on the association between increasing children's outdoor activity time and the prevention of myopia. However, none of these systematic reviews were limited to randomised controlled trials (RCTs), as they included all types of study designs, including observational studies and non-RCTs, in addition to RCTs.

OBJECTIVES

To assess the effects of interventions to increase outdoor time on the incidence and progression of myopia in children.

SEARCH METHODS

We searched CENTRAL, MEDLINE Ovid, Embase Ovid, ISRCTN registry, ClinicalTrials.gov, and the WHO ICTRP with no language restrictions. The databases were last searched on 24 June 2022.

SELECTION CRITERIA

We included RCTs and cluster-RCTs in which interventions were performed to increase the outdoor time for children with the aim of preventing the incidence and progression of myopia.

DATA COLLECTION AND ANALYSIS

We employed the standard methods recommended by Cochrane and assessed the certainty of the evidence using GRADE. We considered the following outcome measures: mean change in refractive error from baseline, incidence of myopia, mean change in the axial length from baseline, mean change in unaided distance visual acuity from baseline, quality of life and adverse event.

MAIN RESULTS

We included five RCTs in this review, four of which were cluster-RCTs. The total number of participants was 10,733. The included participants were primary school children, most of whom were in first or second grade (aged six to nine years). Four cluster-RCTs involved school-based interventions to encourage children to spend more time outdoors. The interventions included classroom time outdoors, routine for spending recess outdoors, motivational tools for spending time outdoors, and encouragement through electronic information tools. The intervention groups had less change in refractive errors in the direction of myopia; however, 95% confidence intervals (CIs) included no benefit or both benefit and harm at years one and three, and differences at year two included both clinically important and unimportant benefits (at 1 year: mean difference (MD) 0.08 dioptres (D), 95% CI -0.01 to 0.17; 4 studies, 1656 participants; low-certainty evidence; at 2 years: MD 0.13 D, 95% CI 0.06 to 0.19; 4 studies, 2454 participants; moderate-certainty evidence; at 3 years: MD 0.17 D, 95% CI -0.17 to 0.51; 1 study, 729 participants; low-certainty evidence). Our protocol defined a difference of 0.1 D in the change in refractive error as clinically important. At one year, the difference was less than 0.1 D, but at two and three years it was more than 0.1 D. The incidence of myopia was lower in the intervention groups compared to the control groups, but 95% CIs included no change or clinically unimportant benefits (at 1 year: 7.1% with intervention versus 9.5% with control; risk ratio (RR), 0.82, 95% CI 0.56 to 1.19; 3 studies, 1265 participants; low-certainty evidence; at 2 years: 22.5% with intervention versus 26.7% with control; RR 0.84, 95% CI 0.72 to 0.98; 3 studies, 2104 participants; moderate-certainty evidence; at 3 years: 30.5% with intervention versus 39.8% with control; RR 0.77, 95% CI 0.59 to 1.01; 1 study, 394 participants; moderate-certainty evidence). Our protocol defined a difference of 3% in the incidence of myopia as clinically important. At one year, the difference was 2.4%, but there were clinically important differences between the two groups at two (4.2%) and three years (9.3%). The intervention groups had smaller changes in axial lengths in the direction of myopia than the control groups; however, 95% CIs included no benefit or both benefit and harm at years one and three (at 1 year: MD -0.04 mm, 95% CI -0.09 to 0; 3 studies, 1666 participants; low-certainty evidence; at 2 years: MD -0.04 mm, 95% CI -0.07 to -0.01; 3 studies, 2479 participants; moderate-certainty evidence; at 3 years: MD -0.03 mm, 95% CI -0.13 to 0.07; 1 study, 763 participants; moderate-certainty evidence). No included studies reported changes in unaided distance visual acuity and quality of life. No adverse events were reported.

AUTHORS' CONCLUSIONS

The intervention methods varied from adopting outdoor activities as part of school lessons to providing information and motivation for encouraging outdoor activities. The results of this review suggest that long-term interventions to increase the time spent outdoors may potentially reduce the development of myopia in children. However, although the interventions may also suppress the progression of myopia, the low certainty of evidence makes it difficult to draw conclusions. Further research needs to be accumulated and reviewed.

Relationship between myopia control and amount of corneal refractive change after orthokeratology lens treatment

BACKGROUND

To evaluate the relationship between amount of corneal refractive change (CRC) after wearing orthokeratology (Ortho-K) lenses and axial length (AL) growth.

METHODS

We retrospectively enrolled 77 patients (77 eyes) aged 8-14 years who wore Ortho-K lenses more than 12 months. We divided the patients into 2 subgroups: spherical equivalent (SE) ≤ -3.0 D and SE > -3.0 D subgroup. The sagittal and tangential curvature maps and corneal topographic data within the 8-mm diameter ring at the baseline and during follow-up visits after wearing Ortho-K lens were recorded in addition to the area, height, and volume of the CRC region. The AL data were recorded at the baseline and during follow-up visits. Multivariate linear regression was conducted to analyze associations between the area, height, and volume of the CRC region, AL elongation, and SE.

RESULTS

The average change in the CRC region was 9.77 ± 0.60 D in height, 16.66 ± 3.61 mm2 in area, and 87.47 ± 8.96 D*mm2 in volume on the tangential diagram after wearing Ortho-K lenses for 3 months. The AL showed a change of 0.19 ± 0.14 mm after 1 year of Ortho-K lens wear (P < 0.05). At 1 year, AL elongation was negatively correlated with the area (P = 0.019) and volume (P < 0.001) of the CRC region. At 1 year, for every 1-mm2 increase in the area and every 1-D*mm2 increase in the volume of the CRC region, the average AL elongation decreased by 0.01 mm and 0.002 mm, respectively, in the multivariate analysis. In patients with SE ≤ -3.0 D, AL elongation was negatively correlated with the CRC-region volume (β = -0.002, P = 0.018), and in patients with SE > -3.0 D, AL elongation was negatively correlated with the CRC-region area (β = -0.017, P = 0.016).

CONCLUSIONS

The AL elongation-control efficacy of Ortho-K lenses may be related to the area and volume of the CRC region.

Oral administration of caffeine metabolite 7-methylxanthine is associated with slowed myopia progression in Danish children

PURPOSE

Myopia is associated with an increased risk of permanent vision loss. The caffeine metabolite 7-methylxanthine (7-MX), licensed in Denmark since 2009 as a treatment to reduce the rate of childhood myopia progression, is the only orally administered therapy available. The purpose of the current study was to assess the rate of myopia progression in children taking 7-MX.

METHODS

Longitudinal cycloplegic refraction and axial length data for 711 myopic children from Denmark treated with varying doses of oral 7-MX (0-1200 mg per day) were analysed using linear mixed models.

RESULTS

The median age at baseline was 11.1 years (range 7.0 -15.0 years). Children were followed for an average of 3.6 years (range 0.9-9.1 years) and the average myopia progression was 1.34 dioptres (D) (range -6.50 to +0.75 D). Treatment with 7-MX was associated with a reduced rate of myopia progression (p<0.001) and axial elongation (p<0.002). Modelling suggested that, on average, an 11-year-old child taking 1000 mg 7-MX daily would develop -1.43 D of myopia over the next 6 years, compared with -2.27 D if untreated. Axial length in this child would increase by 0.84 mm over 6 years when taking a daily dose of 1000 mg of 7-MX, compared with 1.01 mm if untreated. No adverse effects of 7-MX therapy were reported.

CONCLUSIONS

Oral intake of 7-MX was associated with reduced myopia progression and reduced axial elongation in this sample of myopic children from Denmark. Randomised controlled trials are needed to determine whether the association is causal.

Deep learning system to predict the 5-year risk of high myopia using fundus imaging in children

Our study aims to identify children at risk of developing high myopia for timely assessment and intervention, preventing myopia progression and complications in adulthood through the development of a deep learning system (DLS). Using a school-based cohort in Singapore comprising of 998 children (aged 6-12 years old), we train and perform primary validation of the DLS using 7456 baseline fundus images of 1878 eyes; with external validation using an independent test dataset of 821 baseline fundus images of 189 eyes together with clinical data (age, gender, race, parental myopia, and baseline spherical equivalent (SE)). We derive three distinct algorithms - image, clinical and mix (image + clinical) models to predict high myopia development (SE ≤ -6.00 diopter) during teenage years (5 years later, age 11-17). Model performance is evaluated using area under the receiver operating curve (AUC). Our image models (Primary dataset AUC 0.93-0.95; Test dataset 0.91-0.93), clinical models (Primary dataset AUC 0.90-0.97; Test dataset 0.93-0.94) and mixed (image + clinical) models (Primary dataset AUC 0.97; Test dataset 0.97-0.98) achieve clinically acceptable performance. The addition of 1 year SE progression variable has minimal impact on the DLS performance (clinical model AUC 0.98 versus 0.97 in primary dataset, 0.97 versus 0.94 in test dataset; mixed model AUC 0.99 versus 0.97 in primary dataset, 0.95 versus 0.98 in test dataset). Thus, our DLS allows prediction of the development of high myopia by teenage years amongst school-going children. This has potential utility as a clinical-decision support tool to identify "at-risk" children for early intervention.

Macular function in patients with medium myopia

Purpose

This work aims at assessing whether electrophysiological functional changes in the macular region appear in medium myopia, even in the presence of a normal macular OCT scan and how axial length correlates with macular OCT parameters in medium myopia.

Methods

The study included right eyes of 17 patients with myopia of medium degree (SE <  − 6D to >  − 3D). Control group consisted of 20 eyes of patients of age and sex that matched healthy controls with normal macular and optic nerve OCT results and normal axial length. Full ophthalmic examination (the distance best-corrected visual acuity, intraocular pressure, refractive error, the anterior and posterior segment of the eye in a slit lamp, the axial length of the eyeball) with OCT of the macular and optic disk and the PERG test were performed in the study and control groups. Only the patients with normal ophthalmic and OCT examination results were qualified. The interview covering questions on risk factors of myopia onset and progression such as prematurity, family history of myopia was carried out in both groups. In myopic group, the question relating to time of near work was also asked. Study and control groups were tested with the use of Shapiro–Wilk, Mann–Whitney, Student’s t test, Pearson and Spearman's rank correlation tests.

Results

AL was significantly longer in myopia group (p < 0.01), and SE value was lower (p < 0.01). Longer implicit time of P50 was found in the study group, but amplitudes of P50 and N95 waves were not significantly reduced (p < 0.05). AL showed correlations with P50 implicit time (p < 0.05) and with reduction in retinal fiber nerve layer and ganglion cells and inner plexus layer (p < 0.05).

Conclusion

Patients with myopia of medium degree have a dysfunction of retinal cone system of the macular region even when OCT scans show no abnormalities. Elongation of AL correlates with reduction in retinal fiber nerve layer and ganglion cells and inner plexus layer. Longitudinal follow-up studies may answer the question whether this increase in implicit time may be indicative of a faster myopia progression or of myopic retinal pathology, i.e., whether it may help to determine which patient would benefit from earlier or more intensive management of myopia progression.

Longitudinal analysis of 5-year refractive changes in a large Japanese population

Refractive changes are reportedly affected by age, sex, and current refractive error. To clarify the pattern of refractive changes in a Japanese population, we conducted a 5-year follow-up longitudinal analysis of spherical equivalent (SE) refractive changes with stratification by sex, age, and SE in 593,273 eyes from Japanese individuals ages 3–91 years. The 5-year SE change with myopic shift dramatically increased over time after age 4 years, and the largest change was observed in both males and females who were age 8 years at baseline [males: − 2.654 ± 0.048 diopters (D); females: − 3.110 ± 0.038 D]. During school age, the 5-year myopic change was greater in females than in males, and emmetropic and low-to-moderate myopic eyes underwent larger myopic changes than hyperopic and high-to-severe myopic eyes. After the peak at age 8 years, the 5-year myopic change gradually declined with age and fell below − 0.25 D at age 27 in males and age 26 years in females. The 5-year SE changes transitioned from a myopic to a hyperopic shift at age 51 in both sexes, and hyperopization advanced more quickly in hyperopic eyes. Our findings highlight the importance of myopia prevention in school-aged children.

Association of Age at Myopia Onset With Risk of High Myopia in Adulthood in a 12-Year Follow-up of a Chinese Cohort

Importance

Early-onset myopia is well known to progress to high myopia in adulthood. However, no accurate estimation of how a specific age at myopia onset is associated with the probability of developing high myopia in adulthood is available, and a very-long-term follow-up study with data from annual visits is needed.

Objective

To estimate the risk of developing high myopia in adulthood associated with a specific age at myopia onset from a data set with a 12-year annual follow-up.

Design, Setting, and Participants

This ongoing, population-based prospective cohort study of twins was conducted in Guangzhou, China, on July 11, 2006. Data from baseline to August 31, 2018, were analyzed. The first-born twins completed follow-up until 17 years or older, and the 443 participants (after exclusions) who developed myopia were included in the analysis. Data were analyzed from September 1, 2018, to January 20, 2020.

Main Outcomes and Measures

Age at myopia onset was determined by prospective annual cycloplegic refractions (365 participants [82.4%]) or with a questionnaire. Refraction in adulthood was defined as the cycloplegic refraction measured at the last follow-up visit.

Results

Among the 443 eligible participants (247 [55.8%] female; mean [SD] age at myopia onset, 11.7 [2.0] years), 54 (12.2%) developed high myopia (spherical equivalent, -6.00 diopters or worse determined by cycloplegic refractions) in adulthood. Among participants with age at myopia onset of 7 or 8 years, 14 of 26 (53.9%; 95% CI, 33.4%-73.4%) developed high myopia in adulthood; among those with onset at 9 years of age, 12 of 37 (32.4%; 95% CI, 18.0%-49.8%); among those with onset at 10 years of age, 14 of 72 (19.4%; 95% CI, 11.1%-30.5%); among those with onset at 11 years of age, 11 of 78 (14.1%; 95% CI, 7.3%-23.8%); and among those with onset at 12 years or older, 3 of 230 (1.3%; 95% CI, 0.2%-3.8%). Results of multivariate logistic regression analysis suggested that the risk of developing high myopia in adulthood decreased significantly with delay in the age at myopia onset (odds ratio, 0.44; 95% CI, 0.36-0.55; P < .001), from greater than 50% for 7 or 8 years of age to approximately 30% for 9 years of age and 20% for 10 years of age.

Conclusions and Relevance

These findings suggest that the risk of high myopia is relatively high in children with myopia onset during the early school ages. Each year of delay in the age at onset substantially reduces the chance of developing high myopia in adulthood, highlighting the importance of identifying effective prevention strategies under investigation, such as increasing outdoor time.

Rapid Myopic Progression in Childhood Is Associated With Teenage High Myopia

Purpose

The purpose of this study was to evaluate the association of childhood progression of spherical equivalent (SE) with high myopia (HM) in teenagers in the Singapore Cohort of Risk factors for Myopia (SCORM).

Methods

We included 928 SCORM children followed over a mean follow-up of 6.9 ± 1.0 years from baseline (6–11 years old) until their teenage years (12–19 years old). Cycloplegic autorefraction and axial length (AL) measurements were performed yearly. The outcomes in teenagers were HM (SE ≤ −5 diopter [D)], AL ≥ 25 mm, SE and AL. Three-year SE and AL progression in childhood and baseline SE and AL with outcomes were evaluated using multivariable logistic or linear regression models, with predictive performance of risk factors assessed using the area under the curve (AUC).

Results

At the last visit, 9.8% of teenagers developed HM and 22.7% developed AL ≥ 25 mm. In multivariate regression analyses, every −0.3 D/year increase in 3-year SE progression and every 0.2 mm/year increase in 3-year AL progression were associated with a −1.14 D greater teenage SE and 0.52 mm greater teenage AL (P values < 0.001). The AUC (95% confidence interval [CI]) of a combination of 3-year SE progression and baseline SE for teenage HM was 0.97 (95% CI = 0.95 – 0.98). The AUC of 3-year AL progression and baseline AL for teenage AL ≥ 25 mm was 0.91 (95% CI = 0.89 – 0.94).

Conclusions

Three-year myopia progression in childhood combined with baseline SE or AL were good predictors of teenage HM. Clinicians may use this combination of factors to guide timing of interventions, potentially reducing the risk of HM later in life.

Trends in research related to high myopia from 2010 to 2019: a bibliometric and knowledge mapping analysis

AIM

To evaluate the global trends in and explore hotspots of high myopia (HM) research.

METHODS

This bibliometric analysis was used to reveal the publication trends in HM research field based on the Web of Science Core Collection (WoSCC). VOSviewer version 1.6.13 software was used to analyze the data and construct a knowledge map including the yearly publication number, journals, countries, international collaborations, authors, research hotspots, and intellectual base in HM.

RESULTS

The search engine found 3544 peer-reviewed publications on HM between 2010 and 2019, and the yearly research output substantially elevated over the past decade. China is the top publishing country, and Sun Yat-sen University was the most active academic institution. Jonas JB is the top publishing scientist, and Investigative Ophthalmology and Visual Science (IOVS) was the most productive journal. The highest cited references mainly focused on epidemiology and management. The keywords formed 6 clusters: 1) refractive surgery; 2) etiology and clinical characteristics; 3) the mechanism of eye growth; 4) management for myopic maculopathy; 5) vitrectomy surgical treatment; 6) myopia-associated glaucoma-like optic neuropathy.

CONCLUSION

The evaluation of development trends based on the data extracted from WoSCC can provide valuable information and guidance for ophthalmologists and public health researchers to improve management procedures in HM field.

Progression of myopia in children and teenagers: a nationwide longitudinal study

Background

Data on myopia prevalence and progression in European children are sparse. The aim of this work was to evaluate the progression of myopia in children and teenagers in a large prospective study.

Methods

A prospective study involving a nationwide cohort. Myopia was defined as a spherical equivalent (SE) of ≤ –0.50 diopters (D). Data on refractive error, gender and age were collected in 696 optical centres in France between 2013 and 2019, including 136 333 children (4–17 years old) in the analysis.

Progression of myopia was assessed between the first visit and the last visit over up to 6.5 years.

Results

Mean age was 11.3±3.8 years (55.0% of female). The proportion of children progressing more than –0.50 D per year was higher in age groups 7–9 years and 10–12 years and in children with SE ≤ –4.00 D at first visit, representing 33.1%, 29.4% and 30.0% of these groups, respectively. In multivariate analysis, progression during the first 11–24 months was higher in the 7–9 and 10–12 age groups (–0.43 D and –0.42 D, respectively), for higher SE at baseline (at least –0.33 D for SE ≤ –1 D) and for girls (–0.35 D).

Conclusion

This is the first French epidemiological study to investigate myopia progression in a large-scale cohort of children. Sex, age groups and myopia severity are associated with differing rates of progression.

Association of Parental Myopia With Higher Risk of Myopia Among Multiethnic Children Before School Age

Importance

Parental myopia is an important risk factor for preschool myopia in Asian children. Further investigation of the association between parental myopia and early-onset myopia risk in other racial/ethnic groups, such as African American and Hispanic white children, could improve understanding of the etiology and treatment of this condition.

Objective

To investigate the association of parental myopia with refractive error and ocular biometry in multiethnic children aged 6 to 72 months.

Design, Setting, and Participants

This cohort study pooled data from children in 3 population-based studies with comparable design from the US, Singapore, and Australia. Parental myopia was defined as the use of glasses or contact lenses for distance viewing by the child's biological parent(s). Multivariable regressions were conducted to assess the association of parental myopia. Data were collected from 2003 to 2011 and analyzed from 2017 to 2019.

Main Outcomes and Measures

Cycloplegic refraction and prevalence of myopia (spherical equivalent refractive error of≤-0.5 diopters [D]) in the more myopic eye.

Results

The analysis cohort included 9793 children, including 4003 Asian, 2201 African American, 1998 Hispanic white, and 1591 non-Hispanic white participants (5106 boys [52.1%]; mean [SD] age, 40.0 [18.9] months). Compared with children without parental myopia, the odds ratios for early-onset myopia were 1.42 (95% CI, 1.20-1.68) for children with 1 parent with myopia, 2.70 (95% CI, 2.19-3.33) for children with 2 parents with myopia, and 3.39 (95% CI, 1.99-5.78) for children with 2 parents with childhood-onset myopia. Even among children without myopia, parental myopia was associated with a greater ratio of axial length to corneal curvature radius (regression coefficient for myopia in both parents, 0.023; P < .001) and more myopic refractive error (regression coefficient for myopia in both parents, -0.20 D; P < .001). Effects of parental myopia were observed in all 4 racial/ethnic groups and across age groups except those younger than 1 year. However, parental myopia was not associated with the age-related trends of refractive error (regression coefficient for children without parental myopeia, 0.08; for children with 2 parents with myopia, 0.04; P = .31 for interaction) and ratio of axial length to corneal curvature radius (regression coefficient for children without parental myopeia, 0.031; for children with 2 parents with myopia, 0.032; P = .89 for interaction) beyond infancy.

Conclusions and Relevance

Parental myopia, especially childhood-onset parental myopia, was associated with a greater risk of early-onset myopia in Asian, Hispanic, non-Hispanic white, and African American children. The observed associations of parental myopia in children as early as 1 year of age and in children without myopia suggests that genetic susceptibility may play a more important role in early-onset myopia and that parental myopia may contribute to myopia in children by setting up a more myopic baseline before school age.

Effect of Chinese eye exercises on change in visual acuity and eyeglasses wear among school-aged children in rural China: a propensity-score-matched cohort study

BACKGROUND

Daily "eye exercises," massaging of periocular acupuncture pressure points, have been part of China's national vision care policy in schools for some 50 years. However, the effect of eye exercises on myopia progression and eyeglasses wear has not been definitively investigated. This study evaluates the effectiveness of eye exercises on visual acuity and the propensity of rural children to wear eyeglasses.

METHODS

Cohort study in 252 randomly-selected rural schools with baseline in September 2012 and follow up surveys 9 and 21 months later. Outcomes were assessed using propensity-score matching (PSM), multivariate linear regression and logistic regression to adjust for differences between children performing and not performing eye exercises.

RESULTS

Among 19,934 children randomly selected for screening, 2374 myopic (spherical equivalent refractive error ≤ - 0.5 diopters in either eye) children (11.9%, mean age 10.5 [Standard Error 1.08] years, 48.5% boys) had VA in either eye ≤6/12 without eyeglasses correctable to > 6/12 with eyeglasses. Among these who completed the 21-month follow up, 1217 (58.2%) children reported practicing eye exercises on school days and 874 (41.8%) did not. After propensity-score matching, 1652 (79%) children were matched: 826 (50%) in the Eye Exercises group and 826 (50%) in the No Exercise group. Performing eye exercises was not associated with change in LogMAR uncorrected visual acuity and wear of eyeglasses, using either logistic regression or PSM at 9 or 21 months.

CONCLUSIONS

We found no evidence for an effect of eye exercises on change in vision or eyeglasses wear.

TRIAL REGISTRATION

The original trial (Registration site: http://isrctn.org. Registration number: ISRCTN03252665) was retrospectively registered 25/09/2012.

The Effect of Treatment Zone Decentration on Myopic Progression during Or-thokeratology

Purpose: To evaluate the relationship between magnitude of orthokeratology (OrthoK) treatment zone decentration and 2-year axial length (AL) elongation in myopic children.Methods: One-hundred and one Chinese children who wore OrthoK contact lenses for 2 years. The magnitude and direction of the OrthoK treatment zone center from the entrance pupil center were recorded after 3 and 24 months of lens wear along with AL measurement. Stepwise multiple linear regression analysis was performed to assess which factors significantly affected an increase in AL.Results: After 3 and 24 months of OrthoK treatment, the mean (± standard deviation [SD]) magnitude of the OrthoK treatment zone decentration was 0.64 ± 0.38 mm and 0.68 ± 0.32 mm, respectively. There were no significant differences between the two time points (P > .05). After 2 years of OrthoK contact lenses wear, the mean (± SD) AL growth was 0.36 ± 0.34 mm. The axial elongation was slightly correlated with baseline age of subjects (r = -0.073, P < .001), baseline spherical equivalent refractive error (r = -0.088, P < .001) and magnitude decentration of treatment zone (r = -0.190, P = .027).Conclusions: The decentration of OrthoK treatment zone stabilizes after 3 months of lens wear and slightly decreases AL growth.

IMI - Myopia Control Reports Overview and Introduction

With the growing prevalence of myopia, already at epidemic levels in some countries, there is an urgent need for new management approaches. However, with the increasing number of research publications on the topic of myopia control, there is also a clear necessity for agreement and guidance on key issues, including on how myopia should be defined and how interventions, validated by well-conducted clinical trials, should be appropriately and ethically applied. The International Myopia Institute (IMI) reports the critical review and synthesis of the research evidence to date, from animal models, genetics, clinical studies, and randomized controlled trials, by more than 85 multidisciplinary experts in the field, as the basis for the recommendations contained therein. As background to the need for myopia control, the risk factors for myopia onset and progression are reviewed. The seven generated reports are summarized: (1) Defining and Classifying Myopia, (2) Experimental Models of Emmetropization and Myopia, (3) Myopia Genetics, (4) Interventions for Myopia Onset and Progression, (5) Clinical Myopia Control Trials and Instrumentation, (6) Industry Guidelines and Ethical Considerations for Myopia Control, and (7) Clinical Myopia Management Guidelines.

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.

Age of onset of myopia predicts risk of high myopia in later childhood in myopic Singapore children

PURPOSE

To investigate the effect of age of myopia onset on the severity of myopia later in life among myopic children.

METHODS

In this prospective study, school children aged 7-9 years from the Singapore Cohort Of the Risk factors for Myopia (SCORM) were followed up till 11 years (n = 928). Age of myopia onset was defined either through questionnaire at baseline (age 7-9 years) or subsequent annual follow-up visits. Age of onset of myopia was a surrogate indicator of duration of myopia progression till age 11 years. Cycloplegic refraction and axial length were measured at every annual eye examination. High myopia was defined as spherical equivalent of ≤-5.0 D. A questionnaire determined the other risk factors.

RESULTS

In multivariable regression models, younger age of myopia onset (per year decrease) or longer duration of myopia progression was associated with high myopia (odds ratio (OR) = 2.86; 95% CI: 2.39 to 3.43), more myopic spherical equivalent (regression coefficient (β) = -0.86 D; 95% CI: -0.93 to -0.80) and longer axial length (β = 0.28 mm; 95% CI: 0.24 to 0.32) at aged 11 years, after adjusting for gender, race, school, books per week and parental myopia. In Receiver Operating Curve (ROC) analyses, age of myopia onset alone predicted high myopia by 85% (area under the curve = 0.85), while the addition of other factors including gender, race, school, books per week and parental myopia only marginally improved this prediction (area under the curve = 0.87).

CONCLUSIONS

Age of myopia onset or duration of myopia progression was the most important predictor of high myopia in later childhood in myopic children. Future trials to retard the progression of myopia to high myopia could focus on children with younger age of myopia onset or with longer duration of myopia progression.

Epidemiology of Myopia

Myopia is not a simple refractive error, but an eyesight-threatening disease. There is a high prevalence of myopia, 80% to 90%, in young adults in East Asia; myopia has become the leading cause of blindness in this area. As the myopic population increases globally, the severity of its impact is predicted. Approximately one fifth of the myopic population has high myopia (≥-6 diopters), which results in irreversible vision loss such as retinal detachment, choroidal neovascularization, cataracts, glaucoma, and macular atrophy. The increasing prevalence of school myopia in the past few decades may be a result of gene-environment interactions. However, earlier school myopia onset would accompany faster myopia progression and greater risk of high myopia later in life. Recently, there have been effective interventions to delay the onset of myopia, such as outdoor activity and decreasing the duration of near work. Hyperopia (≤0.5 diopters) is a predictor of myopia. Pharmacological agents and optic interventions such as low-concentration atropine and orthokeratology may slow progression in myopic children. Novel surgeries and anti-vascular endothelial growth factor drugs could deal with some myopic complications. From available evidence, the prevention, control, and treatment of myopia seem to be promising. However, to reduce the impact of myopia in future decades, more work and effort are still needed, including that by governments and intercountry eye health organizations.

The Association between Near Work Activities and Myopia in Children-A Systematic Review and Meta-Analysis

Myopia has a multifactorial etiology, although environmental factors are predominant in determining its current patterns. Currently, associations between near work activities and myopia have not been consistently observed. Therefore, we performed a systematic review to quantify the effect of near work activities on myopia in children. Relevant articles published between 1989 and 2014 were identified in MEDLINE, Embase, and the Cochrane Library, and the citation lists were reviewed. Twelve cohort studies and 15 cross-sectional studies were included (25,025 children aged between 6 and 18 years). The I² statistic was used to assess heterogeneity. Study-level data were pooled using a random-effects model or a fixed-effects model (when less than 5 studies were included). We found that more time spent on near work activities was associated with higher odds of myopia (odds ratio [OR] = 1.14; 95% confidence interval [CI] = 1.08–1.20) and that the odds of myopia increased by 2% (OR:1.02; 95% CI = 1.01–1.03) for every one diopter-hour (hr) more of near work per week. Therefore, the development of a strategy to reduce the impact of near work on myopia would be important for preventing myopia in children.

Effect of outdoor activity on myopia onset and progression in school-aged children in northeast China: the Sujiatun Eye Care Study

Background

Due to its high prevalence and associated sight-threatening pathologies, myopia has emerged as a major health issue in East Asia. The purpose was to test the impact on myopia development of a school-based intervention program aimed at increasing the time student spent outdoors.

Methods

A total of 3051 students of two primary (grades 1-5, aged 6-11) and two junior high schools (grades 7-8, aged 12-14) in both urban and rural Northeast China were enrolled. The intervention group (n = 1735) unlike the control group (n = 1316) was allowed two additional 20-min recess programs outside the classroom. A detailed questionnaire was administered to parents and children. Uncorrected visual acuity (UCVA) was measured using an E Standard Logarithm Vision Acuity Chart (GB11533-2011) at baseline, 6-month and 1-year intervals. A random subsample (n = 391) participated in the clinic visits and underwent cycloplegia at the beginning and after 1 year.

Results

The mean UCVA for the entire intervention group was significantly better than the entire control group after 1 year (P < 0.001). In the subgroup study, new onset of myopia and changes in refractive error towards myopia were direction during the study period was significantly lower in the intervention group than in the control group (3.70 % vs. 8.50 %, P = 0.048; -0.10 ± 0.65 D/year vs. -0.27 ± 0.52 D/year, P = 0.005). Changes in axial length and IOP were also significantly lower following the intervention group (0.16 ± 0.30 mm/year vs. 0.21 ± 0.21 mm/year, P = 0.034; -0.05 ± 2.78 mmHg/year vs. 0.67 ± 2.21 mmHg/year, P = 0.006).

Conclusions

Increasing outdoor activities prevented myopia onset and development, as well as axial growth and elevated IOP in children.

Trial registration

Current controlled trials NCT02271373.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-015-0052-9) contains supplementary material, which is available to authorized users.

Influence of ocular wavefront aberrations on axial length elongation in myopic children treated with overnight orthokeratology

PURPOSE

To determine ocular optical parameters that affect axial length elongation in myopic children undergoing overnight orthokeratology.

DESIGN

Prospective, noncomparative study.

PARTICIPANTS

Fifty-nine subjects who met the inclusion criteria were enrolled in this study.

METHODS

Axial length and ocular wavefront aberration were assessed before and 1 year after the start of orthokeratology. Corneal topography was performed, and then corneal multifocality was calculated for a 4-mm pupil. After evaluating simple correlations between axial elongation and optical parameters, multiple linear regression analysis was performed to identify explanatory variables with a statistically significant contribution to axial elongation.

MAIN OUTCOME MEASURES

Axial length and ocular wavefront aberration before and 1 year after the start of orthokeratology.

RESULTS

Fifty-five subjects completed the 1-year follow-up examinations. At baseline, their age ranged from 7.2 to 12.0 years. The manifest spherical equivalent refractive error ranged from -3.50 to -0.75 diopters. The mean axial length significantly increased from 24.20 mm at baseline to 24.43 mm 1 year after treatment. The axial elongation showed significant simple correlations with the change in C2(0), change in second-order aberration, change in coma-like aberration, change in spherical-like aberration, change in total higher-order aberrations, change in corneal multifocality, baseline age, and baseline spherical equivalent refractive error, but not C4(0). Multiple linear regression analysis showed that the change in coma-like aberration was the most relevant variable.

CONCLUSIONS

Asymmetric corneal shapes, rather than concentric and radially symmetric shapes, have a considerable effect on retardation of axial elongation, suggesting that the inhibitory effect of orthokeratology on myopia progression is caused by mechanisms other than the reduction in peripheral hyperopic defocus.

Outdoor activity during class recess reduces myopia onset and progression in school children

PURPOSE

The aim of this study was to investigate the effect of outdoor activity during class recess on myopia changes among elementary school students in a suburban area of Taiwan.

DESIGN

Prospective, comparative, consecutive, interventional study.

PARTICIPANTS

Elementary school students 7 to 11 years of age recruited from 2 nearby schools located in a suburban area of southern Taiwan.

INTERVENTION

The children of one school participated in the interventions, whereas those from the other school served as the control group. The interventions consisted of performing a recess outside the classroom (ROC) program that encouraged children to go outside for outdoor activities during recess. The control school did not have any special programs during recess.

MAIN OUTCOME MEASURES

Data were obtained by means of a parent questionnaire and ocular evaluations that included axial length and cycloplegic autorefraction at the beginning and after 1 year.

RESULTS

Five hundred seventy-one students were recruited for this study, of whom 333 students participated in the interventional program, and 238 students were in the control school. At the beginning of the study, there were no significant differences between these 2 schools with regard to age, gender, baseline refraction, and myopia prevalence (47.75% vs. 49.16%). After 1 year, new onset of myopia was significantly lower in the ROC group than in the control group (8.41% vs. 17.65%; P<0.001). There was also significantly lower myopic shift in the ROC group compared with the control group (-0.25 diopter [D]/year vs. -0.38 D/year; P = 0.029). The multivariate analysis demonstrated that the variables of intervention of the ROC program and higher school year proved to be a protective factor against myopia shift in nonmyopic subjects (P = 0.020 and P = 0.017, respectively). For myopic subjects, school year was the only variable significantly associated with myopia progression (P = 0.006).

CONCLUSIONS

Outdoor activities during class recess in school have a significant effect on myopia onset and myopic shift. Such activities have a prominent effect on the control of myopia shift, especially in nonmyopic children.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Genetic variants on chromosome 1q41 influence ocular axial length and high myopia

As one of the leading causes of visual impairment and blindness, myopia poses a significant public health burden in Asia. The primary determinant of myopia is an elongated ocular axial length (AL). Here we report a meta-analysis of three genome-wide association studies on AL conducted in 1,860 Chinese adults, 929 Chinese children, and 2,155 Malay adults. We identified a genetic locus on chromosome 1q41 harboring the zinc-finger 11B pseudogene ZC3H11B showing genome-wide significant association with AL variation (rs4373767, β = -0.16 mm per minor allele, P(meta) =2.69 × 10(-10)). The minor C allele of rs4373767 was also observed to significantly associate with decreased susceptibility to high myopia (per-allele odds ratio (OR) =0.75, 95% CI: 0.68-0.84, P(meta) =4.38 × 10(-7)) in 1,118 highly myopic cases and 5,433 controls. ZC3H11B and two neighboring genes SLC30A10 and LYPLAL1 were expressed in the human neural retina, retinal pigment epithelium, and sclera. In an experimental myopia mouse model, we observed significant alterations to gene and protein expression in the retina and sclera of the unilateral induced myopic eyes for the murine genes ZC3H11A, SLC30A10, and LYPLAL1. This supports the likely role of genetic variants at chromosome 1q41 in influencing AL variation and high myopia.

The long-term results of using low-concentration atropine eye drops for controlling myopia progression in schoolchildren

PURPOSE

The purpose of this article was to evaluate the long-term efficacy of a low-concentration (LC) atropine eye drop regimen (0.05%-0.1%) for controlling myopia progression in schoolchildren.

METHODS

This retrospective, case-control study enrolled myopic schoolchildren who had been followed-up for at least 3 years from 1999 to 2007. Children who received LC doses of atropine eye drops [initial prescription 0.05%, if progression over -0.5 diopter (D) during a 6-month follow-up then changed to 0.1% atropine] every night at bedtime were included in the LC atropine group, and untreated children served as controls.

RESULTS

A total of 117 children were included in this study. The mean age was 8.4 years. There were 97 children in the LC atropine group and 20 children in the control group. The mean follow-up duration was 4.5 years. In a mixed model analysis, the adjusted myopia progression in the LC atropine group was -0.23 D/year, significantly lower than that of the control group, which was -0.86 D/year (P<0.001). About 80% of the treatment group had slow myopia progression (less than -0.5 D progression per year). In a multivariate analysis, factors such as initial spherical refraction with less myopia and treatment with LC atropine were significantly associated with less myopia progression, but age, sex, and initial astigmatism were not significantly associated (P<0.001, P<0.001, P=0.442, 0.494, and 0.547, respectively).

CONCLUSION

The results of this study demonstrate that long-term and regular instillation of LC atropine eye drops is effective for controlling myopia progression and provides a possible strategy for an initial myopia regimen.

Myopia as a latent phenotype of a pleiotropic gene positively selected for facilitating neurocognitive development, and the effects of environmental factors in its expression

Myopia has become an almost pandemic problem in many populations. There are compelling evidence to suggest that myopia is a hereditary condition. However, myopia would constitute a definite selection disadvantage during most stages of human evolution, which is incompatible with its moderate to high prevalence in most modern populations. The rapid upsurge of myopia over just a few decades also implies that its inheritance does not follow any of the usual patterns, and environmental factors may have an important role in precipitating its occurrence in those who are genetically predisposed. Previous studies showed that myopes were, on average, more intelligent than non-myopes, and this association had been attributed to a biological link between eye growth and brain development. We propose a pleiotropic genetic model to explain the atypical epidemiologic and inheritance pattern of myopia and its relationship with neurocognitive development. This pleiotropic gene was positively selected for its facilitation of human intelligence. The myopic component is a latent phenotype; myopia will not be expressed unless some novel external factors are encountered (i.e. a "quirk" phenomenon). Therefore, the myopic component was selectively neutral in our ancestral environment. The net gain in Darwinian fitness enables the pleiotropic gene to attain a high frequency in the human population, as reflected by our current prevalence of myopia.

Family history of myopia is not related to the final amount of refractive error in low and moderate myopia

BACKGROUND

Previous research has found an association between family history and presence of myopia. It is possible that family history also could be related to the final amount of refractive error developed. If that were true, then family history of myopia could have predictive value for the amount of refractive error a child or young adult would develop after first lens prescription.

METHODS

Consecutive myopic adult outpatients were enrolled during the year 2003. They received a refractive examination and a questionnaire concerning age of onset of lens use, academic achievement, and parental history of myopia.

RESULTS

In the group of 271 mild and moderate myopes (myopia lower than -6 D) there were 157 subjects with at least one myopic parent and 114 subjects without family history. The presence or absence of a family history of myopia was not associated with either the final myopic refractive error (-3.2 +/- 1.5 D and -2.9 +/- 1.3 D, respectively, P = 0.08) or the age of onset of lens use (17.0 +/- 6.2 years vs 18.1 +/- 6.7 years, respectively, P = 0.15).

CONCLUSIONS

In the present retrospective study of a clinical sample of mild and moderate myopic subjects, family history of myopia did not show predictive value for either the age of first prescription, or the final refractive error developed in adulthood.

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 to this there exists a lack of clarity regarding the optimum age, and frequency at which to carry out screening.

OBJECTIVES

The objective of this review is to evaluate the effectiveness of vision screening programmes carried out in schools in reducing the prevalence of undetected, correctable visual acuity deficits due to refractive error in school-age children.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) on The Cochrane Library (Issue 3 2004), MEDLINE (1966 to August 2004) and EMBASE (1980 to August 2004). No language or date restrictions were placed on these searches. To date it has not been possible to carry out any manual searches but it is hoped to include these in a future update.

SELECTION CRITERIA

We planned to include randomised controlled trials including randomised cluster controlled trials.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed study abstracts identified by the electronic searches. No trials were identified that met the inclusion criteria.

MAIN RESULTS

As no trials were identified, no formal analysis was performed. A narrative synthesis of other retrieved studies was undertaken in order to explain current practice.

AUTHORS' CONCLUSIONS

At present there are no robust trials available that allow the benefits of school vision screening to be measured. The disadvantage of attending school with a visual acuity deficit also needs to be quantified. The impact of a screening programme will depend on the geographical, and socio-economic setting in which it is conducted. There is therefore clearly a need for well planned randomised controlled trials, in various settings, to be undertaken so that the potential benefits and harms of vision screening can be measured.

Intraocular pressure associations with refractive error and axial length in children

AIM

To assess whether intraocular pressure (IOP) is associated with refractive error or axial length in children.

METHODS

Of subjects from the Singapore Cohort Study of the Risk Factors for Myopia (SCORM), 636 Chinese children aged 9-11 years from two elementary schools underwent non-contact tonometry, cycloplegic autorefraction, and A-scan biometry during 2001. For analyses, refractive error was categorised into four groups; hypermetropia (spherical equivalent refraction (SE) > or = +1.0D), emmetropia (-0.5D<SE< +1.0D), low myopia (-3.0D<SE< or = -0.5D) and high myopia (SE< or = -3.0D).

RESULTS

Of the 636 children examined, 50.6% were male. The mean IOP was 16.6 (SD 2.7) mm Hg. There were no significant IOP differences between low (mean IOP = 16.4 (2.8) mm Hg) or high myopes (16.7 (2.5) mm Hg) and emmetropes (16.7 (2.9) mm Hg), p = 0.57. IOP was not correlated with spherical equivalent refraction (Spearman correlation, r = 0.009) or axial length (r = 0.030). In regression analyses adjusting for diastolic blood pressure, neither spherical equivalent (regression coefficient = 0.014) nor axial length (regression coefficient = 0.027) were significantly associated with IOP.

CONCLUSION

These findings do not support an association between IOP and refractive error or axial length in children. This questions postulated roles of IOP in the pathogenesis of myopia.

The importance of genes and environment for ocular refraction and its determiners: a population based study among 20-45 year old twins

AIMS

To estimate the heritability for ocular refraction and its determiners in a population based cohort of 20-45 years old twins.

METHODS

114 twin pairs (53 monozygotic and 61 dizygotic) participated. Refraction was determined in cycloplegia and eye dimensions were measured with ultrasound. Educational length was assessed. The heritability was estimated employing aetiological model fitting. Evidence of gene-environment interaction was analysed. Correlations between intrapairwise differences in educational length and in refraction were evaluated.

RESULTS

The heritability was between 0.89 and 0.94 (95% CI: 0.82, 0.96) for refraction, total refraction, axial length, and radius of corneal curvature. Phenotypic variation was mostly due to additive genetic effects. Refraction revealed evidence of gene-environment interaction (r = -0.29 to -0.32; p <0.05). The heritability for anterior chamber depth and lens thickness was between 0.88 and 0.94 (95% CI: 0.81, 0.96) and dominant genetic effects were the most likely explanation. There was no correlation between age and intrapairwise differences in refraction. The dizygotic twins had significant larger intrapairwise differences in educational length (p <0.05), but the differences were not correlated with differences in refraction.

CONCLUSIONS

The results indicate a high heritability for ocular refraction and its determiners and thus suggest that environmental impact on refraction is not significant. However, the epidemiological association between educational length (near work) and myopia, the evidence of increasing myopia prevalence within a few generations, and the theory of gene-environment interaction imply that some individuals might be genetically liable to develop myopia if exposed to certain environmental factors.

Temporal variations in myopia progression in Singaporean children within an academic year

PURPOSE

Excessive nearwork is believed to be associated with myopia development and progression. To investigate this further, we studied refractive error changes and their correlation with nearwork in a cohort of grade school children in Singapore.

METHODS

Cycloplegic autorefraction was performed 5 times over 10 months on 168 children aged 7, 9, and 12 years who were further divided into myopic and nonmyopic subgroups based in their initial refractive errors. Information about nearwork was obtained through diaries filled out over 24 h at the commencement of the study.

RESULTS

Myopia progression was high (overall mean: -0.87 D per year) and largely linear throughout the year, but significantly higher rates were seen after the final school examinations in 7-year-old myopes and nonmyopes. Overall, myopic groups exhibited higher progression rates than nonmyopic groups, although 33.6% of subjects from the latter groups had become myopic by the end of the study. Nearwork scores derived from the diaries were generally not well correlated with overall myopia progression.

CONCLUSIONS

The tendency for myopia progression rates to increase after the final school examinations in 7-year-olds is interpreted as a delayed effect of the intense nearwork associated with preparing for them. The timing of nearwork-diary data collection at the beginning of the study could be responsible for the poor correlation between these data and overall myopia progression rates.

Experimental animal myopia models are applicable to human juvenile-onset myopia

Landmark explorations by Hubel and Wiesel investigating the importance of visual impressions in postnatal development of the visual system demonstrated that neural connections and eye growth can be affected by the absence of a clear retinal image during a critical period of postnatal development. Fundamental theories on neural plasticity and deprivation have recently been established that presume that a reduced quality of the retinal image during infancy and early childhood triggers an elongation of the posterior chamber of the eye, a so-called form deprivation myopia (FDM). In a retrospective multicenter study of 187 patients who suffered from phlyctenular keratitis with corneal opacification since early childhood, we reviewed data on gender, year and age at onset of the disease, refraction, and ultrasound biometry. Compared with the average refraction of +0.5 diopter (D) found in the general population, the mean refraction of -4.43 D that we found in our study demonstrated a marked shift toward myopia of almost 5 D. Patients with an early onset of phlyctenular keratitis had considerably higher myopia (-6.68 D) than those with a late onset (-1.67 D). Additionally, an axial elongation was confirmed by ultrasound biometry. Our average, axial length was 26.53 mm, compared with the epidemiologic mean of 24.00 mm. This myopic shift of 2.53 mm was caused mainly by an enlarged vitreous cavity. These results support the finding that blur can affect eye growth and lead to FDM not only in animal experiments but also in human beings.