Myopia prevalence in Denmark - a review of 140 years of myopia research

Prevalence, sociodemographic risk factors, and coverage of myopia correction among adolescent students in the central region of Portugal

BACKGROUND

Knowing the prevalence of myopia at school age is essential to implement preventive measures and appropriate interventions, ensure access to vision care, promote a healthier educational environment and improve academic performance. The purpose of this study was to determine the prevalence of myopia and its associated sociodemographic risk factors, as well as to estimate the coverage of myopia correction among adolescents in center of Portugal.

METHODS

This cross-sectional study evaluated 1115 adolescents from the 5th to the 9th year of school, with an average of 12.9 years (SD = 1.5) ranging from 10.0 to 18.0 years. Optometric evaluations were carried out in a school environment and consisted of the evaluation of distance visual acuity, assessed using a logarithmic visual acuity chart (ETDRS charts 1 and 2) at 4 m, and measured by refractive error with a pediatric autorefractometer (Plusoptix), by non-cycloplegic. Myopia was defined as spherical equivalent (SE ≤ -0.50 diopter (D)) and uncorrected visual acuity (UVA ≤ 95VAR). Adjusted logistic regression analysis was applied to investigate risk factors.

RESULTS

We found a myopia rate of 21.5% and a high myopia rate of 1.4%. Higher school level and attendance at urban schools were associated with myopia, but no association was found with age or sex. Only 34.6% of myopic adolescents use the best optical correction and 26.4% do not use any type of optical correction.

CONCLUSIONS

Data on the prevalence of refractive problems in Portugal are scarce and heterogeneous. This study, although regional, provides a valuable contribution with a clear and reproducible methodology, following international guidelines and filling gaps in the existing literature. The results show that the rate of myopia in this age group is similar to reports from other European studies. The high rate of adolescents with uncorrected or under-corrected myopia in Portugal is a problem that deserves attention.

Incidence of myopia in Swedish schoolchildren: A longitudinal study

PURPOSE

The prevalence of myopia in Scandinavia tends to be lower than in other parts of the world. This study aimed to investigate the incidence of myopia and its predictors in Swedish children to characterise this trend.

METHODS

A 2-year longitudinal study was conducted following a cohort of schoolchildren aged 8-16 years. Myopia was defined as a spherical equivalent refraction (SER) ≤ -0.50 D. The study enrolled 128 participants, 70 (55%) females with a mean age of 12.0 years (SD = 2.4).

RESULTS

The cumulative incidence of myopia during the follow-up period was 5.5%, and the incidence rate of myopia was 3.2 cases per 100 person-years. Participants with myopia at baseline exhibited a faster increase in refractive error during the follow-up period. Likewise, participants with two myopic parents exhibited a more marked change towards myopia, regardless of their initial refractive error.

CONCLUSION

In the current study, similar to prevalence, the incidence of myopia was low when compared with other parts of the world. These results lead us to formulate a new hypothesis that the normal emmetropisation process may be protected by low educational pressure practised in Sweden during early childhood. Further research is necessary to test this new hypothesis.

The role of phacoemulsification surgery in the incidence rate of rhegmatogenous retinal detachment

PURPOSE

To investigate changes in the incidence rate of primary rhegmatogenous retinal detachment (RRD) surgery over time and to determine to what extent these changes can be attributed to pseudophakia.

METHODS

This nationwide cohort study was based on national patient registries. The study population comprised individuals at risk of RRD aged 40 years and above from 2006 to 2021 in Denmark. The primary outcome was RRD incidence, and the exposure was phacoemulsification surgery. A chart review was conducted to validate and examine the lens status of the outcome.

RESULTS

The crude and age-adjusted incidence rate of RRD in the Danish population increased significantly during the study period. The largest increase in RRD was seen in phakic RRD (phRRD) (65%), whereas pseudophakic RRD (pRRD) accounted for 35% of the total increase. A chart review revealed that 17% of phRRDs were misclassified as pseudophakic, resulting in pRRD accounting for a total of 45% of the increase in RRD. The prevalence of pseudophakia in Denmark grew significantly for all age groups and for both sexes (p = 10-6) from 2006 to 2021, but the 1-year incidence of pRRD in the pseudophakic population was constant throughout the entire period.

CONCLUSION

The incidence rate of RRD is continuing to increase in Denmark. The increase in phRRD remains undetermined, and while the risk of pRRD seemed to be constant during the study period, 45% of the overall increase in RRD could be attributed to the rise of a growing pseudophakic population.

Two-Year Results of 0.01% Atropine Eye Drops and 0.1% Loading Dose for Myopia Progression Reduction in Danish Children: A Placebo-Controlled, Randomized Clinical Trial

We investigated the two-year safety and efficacy of 0.1% loading dose and 0.01% low-dose atropine eye drops in Danish children for reduction in myopia progression in an investigator-initiated, placebo-controlled, double-masked, randomized clinical trial. Ninety-seven six- to twelve-year old myopic participants were randomized to 0.1% loading dose for six months and then 0.01% for eighteen months (loading dose group, N = 33), 0.01% for two years (0.01% group, N = 32) or placebo for two years (placebo, N = 32). Axial length (AL) and spherical equivalent refraction (SER) were primary outcomes. Secondary outcomes included adverse events and reactions, choroidal thickness, and other ocular biometrical measures. Outcomes were measured from baseline and at six-month intervals. Individual eyes nested by participant ID were analyzed with linear-mixed model analysis. Data were analyzed with intention-to-treat. Mean AL was 0.08 mm less (95% confidence interval (CI): -0.01; 0.17, p-value = 0.08) in the 0.1% loading dose and 0.10 mm less (95% CI: 0.01; 0.19, p-value = 0.02) in the 0.01% group after two years of treatment compared to placebo. Mean SER progression was 0.12 D (95% CI: -0.10; 0.33) less in the loading dose and 0.26 D (95% CI: 0.04; 0.48) less in the 0.01% groups after two years of treatment compared to placebo (p-value = 0.30 and 0.02, respectively). In total, 17 adverse events were reported in the second-year follow-up, and all were rated as mild. Adjusting for iris color did not affect treatment effect estimates. Intra-ocular pressure increased over two years comparably between all groups but remained within normal limits. Two-year treatment with 0.01% low-dose atropine eye drops is a safe and moderately efficacious intervention in Danish children for reducing myopia progression.

Risk factors for myopia among children and adolescents: an umbrella review of published meta-analyses and systematic reviews

AIMS

To identify potential risk factors for myopia in children and adolescents and assess the credibility of each evidence, providing reference for the development of myopia prevention strategies.

METHODS

We searched PubMed, Web of Science and Embase databases from inception to April 2022 to find systematic reviews or meta-analyses investigating the relationship between potential risk factors and myopia, and conducted an umbrella review. We recalculated the pooled effect sizes and 95% CIs of each potential risk factor through random-effects model, and reported its 95% prediction interval and between-study heterogeneity. Small-study effect and excess of significance bias were assessed to reveal potential publication bias.

RESULTS

Twelve publications were included in this umbrella review, including eight meta-analyses and four qualitative systematic reviews. Twenty-two factors were identified, of which 16 were analysed quantitatively. Ten factors showed statistically significant association with myopia. Myopia in one or two parents and per additional hour of time spend outdoors per week were rated as highly suggestive evidence. Near work and gender were evaluated as suggestive evidence. The other five factors are weak evidence.

CONCLUSIONS

We found several risk factors for myopia with different levels of evidence, of which parental myopia presented the strongest association with myopia in children and adolescents. Our findings contribute to a better understanding of the association between potential risk factors and myopia among children and adolescents and are important for informing parenting, education, clinical practice guidelines and public health policy.

PROSPERO TRIAL REGISTRATION NUMBER

CRD42022333053.

Association between dietary nutrient intake and prevalence of myopia in Korean adolescents: evidence from the 7th Korea National Health and Nutrition Examination Survey

Background

The rise in myopia prevalence, particularly among adolescents in East Asia, is a cause for concern. While a combination of environmental and genetic factors is understood to contribute to this trend, the role of dietary nutrients is not yet fully clarified.

Objective

To assess the potential association between the intake of specific nutrients and the prevalence of myopia in a large, population-based sample of Korean adolescents.

Methods

Data from 18,077 adolescents (average age: 15.05 ± 1.67 years; 51.7% male, 48.3% female) who participated in the 7th Korea National Health and Nutrition Examination Survey (KNHANES VII, 2016) were analyzed. Refractive error was measured using an auto-refractor-keratometer (KR-8800) without cycloplegia. Dietary intake of 14 nutrients was assessed through a 24-h personalized dietary recall method.

Results

The study revealed a myopia prevalence of 87.6% among the adolescents. Multivariable models adjusted for age, gender, BMI, and other confounding factors indicated that higher intakes of carbohydrates, proteins, cholesterol, sodium, and vitamin B2 were associated with an increased risk of myopia. Conversely, higher intake of vitamin C was found to be associated with a decreased risk.

Conclusion

The findings suggested a potential association between dietary nutrient intake and myopia prevalence in Korean adolescents. While the study did not establish a causal link, the differences in nutrient intake between the myopic and non-myopic groups could indicate that diet plays a role in the development or progression of myopia. Further research is warranted to corroborate these findings and explore the underlying mechanisms.

Parental awareness of the implications of myopia and strategies to control its progression: A survey-based study

PURPOSE

Myopia has emerged as a significant public health concern. Effective methods have now been developed to delay its onset and progression. However, this information may not be reaching parents, and they are key players in terms of implementing the necessary preventive measures. This study investigated parental awareness of myopia, its implications and the strategies available for controlling it.

METHODS

A self-administered online survey was distributed to parents of children 6-16 years of age. To be eligible to respond, their child had to be myopic or at risk of developing myopia due to family history.

RESULTS

A total of 330 parents completed the survey, of which 321 were included for analysis. Sixty-seven percent of respondents had at least one myopic son/daughter, and most were between -1.00 and -1.75 D. Among parents of myopic children, 20.9% thought that their child's myopia progressed moderately. Sixty-seven percent of parents had a significant level of concern about the progression of the myopia and felt that it was caused mainly by the use of electronic devices and genetics. A generalised linear model showed that parental concern was significantly predicted by the perception of evolution (p < 0.001) and the number of known health-related consequences (p < 0.001). Almost 40% of parents were unaware of the existence of myopia control strategies. Relatives and eye care practitioners are the main sources of information. The most well-known myopia control strategy was myopia control soft contact lenses (29.2%), although the option that most parents would opt for was spectacles with peripheral defocus lenses (47.1%). The selection of a contact-lens-based myopia control method correlated significantly with the age of the children (p < 0.001).

CONCLUSIONS

Society in general and parents in particular need more information about myopia, its consequences and the options available for its control. Eye care practitioners play an important role in this issue.

Relatively Stable Prevalence of Myopia among Swedish Children Aged 4 to 7 Years between 2015 and 2020

SIGNIFICANCE

The global increase of myopia has caused a lot of debate the last years. Previous research of myopia in the Nordic population has shown diverse results, and only a few Swedish studies have been published in the subject the last two decades.

PURPOSE

This study aimed to analyze trends in the prevalence of myopia in a population of Swedish children.

METHODS

A retrospective analysis of medical records for children between 4 and 7 years of age in a region in Sweden was performed. The inclusion criterion was a first glasses prescription for myopia between 2012 and 2020. Children with other eye diseases or syndromes affecting the eye and vision were excluded. Age, sex, uncorrected visual acuity, and cycloplegic refractive values were extracted. The number of myopic children was compared with population data to calculate incidence and estimate prevalence.

RESULTS

During the study period, 427 children between 4 and 7 years old in an average population of 17,200 children were prescribed glasses for myopia. The incidence for myopia increased from 0.11% in 2012 to 0.39% in 2020 ( P < .05). In 2015 to 2020, the prevalence of myopia for the same age group increased from 0.5 to 1.2% ( P < .05). Linear regression of the prevalence of myopia showed a significant increase in the age group of 7 years ( β = 0.2%, R2 = 0.82, P ≤ .05).

CONCLUSIONS

This study found a relatively stable prevalence of myopia among Swedish children aged 4 to 7 years between 2015 and 2020. The prevalence of 1.6% among 7-year-old children is not higher than in previous Scandinavian studies.

The Prevalence and Progression of Myopia in Elementary School Students in Shanxi Province, China During the COVID-19 Pandemic

PURPOSE

To investigate the prevalence of myopia and the risk factors associated with its progression in elementary school students during the COVID-19 pandemic in Shanxi Province, China.

METHODS

The investigation included 960 students spanning first to sixth grade from six elementary schools in Shanxi Province, China. All participants received non-cycloplegic refraction and vision tests in December of 2019 (before the COVID-19 pandemic) and in June of 2020 (after classes resumed). Information concerning the students' eye-use behaviors, physical activities, diet and sleep during the pandemic was collected using a questionnaire survey. A total of 913 students (457 males) completed all tests and the questionnaire.

RESULTS

The overall prevalence rate of myopia was 16.6% in December of 2019, and it increased with age. There was no gender difference in the prevalence of myopia (χ² = 3.210, P = .073), but females exhibited a lower average spherical equivalent (SE) (P = .026). When the classes were resumed 6 months later, the overall prevalence rate of myopia was found to be 39.4%, which was significantly higher than it before the pandemic (χ² = 117.425, P < .001). The average SE of the participants was -0.95D, which was significantly lower than the average SE (-0.43D) before the pandemic (P < .001). SE variation (ΔSE) in grade 6 was significantly higher than that in grade 1. No significant difference in ΔSE was found between males and females. Analyses of ordinary least squares (OLS)-estimated linear, natural logarithmic and quadratic functions revealed that the progression of myopia during the COVID-19 pandemic was significantly correlated with screen time, types of electronic devices, the amount of sleep, age, and the number of parents with myopia.

CONCLUSIONS

The prevalence rate and progression of myopia among elementary school students in Shanxi Province increased significantly during the COVID-19 pandemic, which was likely related to China's home-based online learning programs. Therefore, it is necessary to optimize the educational programs for elementary school students when they study at home. We recommend increased time for outdoor activities and limiting screen time.

Association Between Color Vision Deficiency and Myopia in Chinese Children Over a Five-Year Period

Purpose

To explore the relationship of color vision deficiency with myopia progression and axial elongation in Chinese primary school children during a five-year cohort study.

Methods

A total of 2849 grade 1 students (aged 7.1 ± 0.4 years) from 11 primary schools were enrolled and followed up for five years. Cycloplegic autorefraction and axial length were measured annually. Color vision testing was performed using Ishihara's test and the City University color vision test.

Results

The prevalence of color vision deficiency was 1.68%, with 2.81% in boys and 0.16% in girls. Color-deficient cases consisted of 91.6% deutan and 8.3% protan. Over the five years, the cumulative incidence of myopia was 35.4% (17/48) in the color-vision deficiency group, which was lower than the 56.7% (1017/1794) in the color normal group (P = 0.004). Over the five-year study period, the change in spherical equivalent refraction in the color vision–deficiency group (−1.81 D) was also significantly lower than that in the color normal group (−2.41 D) (P = 0.002).

Conclusions

The lower incidence and slower progression of myopia in children with color-vision deficiency over the five-year follow-up period suggest that color-deficient individuals are less susceptible to myopia onset and development.

Update and guidance on management of myopia. European Society of Ophthalmology in cooperation with International Myopia Institute

The prevalence of myopia is increasing extensively worldwide. The number of people with myopia in 2020 is predicted to be 2.6 billion globally, which is expected to rise up to 4.9 billion by 2050, unless preventive actions and interventions are taken. The number of individuals with high myopia is also increasing substantially and pathological myopia is predicted to become the most common cause of irreversible vision impairment and blindness worldwide and also in Europe. These prevalence estimates indicate the importance of reducing the burden of myopia by means of myopia control interventions to prevent myopia onset and to slow down myopia progression. Due to the urgency of the situation, the European Society of Ophthalmology decided to publish this update of the current information and guidance on management of myopia. The pathogenesis and genetics of myopia are also summarized and epidemiology, risk factors, preventive and treatment options are discussed in details.