Myopia

Progression of Myopia and High Myopia in the Early Treatment for Retinopathy of Prematurity Study: Findings to 3 Years of Age

The prevalence of myopia has been increasing worldwide. Its causes are not completely clear, although genetic and environmental factors are thought to play a role. Data were collected by the Korean Military Manpower Administration. Frequency analysis was used for comparisons of general characteristics. Pearson’s chi-square tests and logistic regression analysis were used to verify the correlations between possible risk factors and the prevalence of myopia or high myopia. The prevalence of myopia (50.6–53.0%) and high myopia (11.3–12.9%) increased each year. These tended to be the highest in patients born in spring, and decreased in the following order according to education level: 4- or 6-year university education or more, high school education or less, and 2- to 3-year college education. Moreover, the prevalence of myopia and high myopia was significantly higher in patients ≤ 60 kg and with a body mass index ≤ 18.5 kg/m2. The prevalence of high myopia was significantly higher in taller patients (≥175 cm). The prevalence of myopia and high myopia increased each year in Korean young adult men and was associated with birth season, education level, height, weight, and body mass index. Tall, lean men were more likely to have high myopia.

Understanding Modifiable Risk Factors for the Development of Myopia

It has been noted that, at higher prevalences, the rate of change in the prevalence of high myopia seems to be disproportionately greater compared with the rate of change in the prevalence of myopia. A simple, evidence-based explanation for this relationship is offered. Using a convenience sample of 41 datasets with prevalence estimates for at least two refractive error thresholds (e.g., -0.50 and -6.00 D) the common slope of the logit vs. refractive threshold was applied to model expected rates of high myopia across the myopia prevalence range and the corresponding ratio of change in high myopia to myopia prevalence. The logit of high myopia is related linearly to the logit of myopia. The ratio of increase in high myopia prevalence to that for myopia prevalence increases with underlying prevalence. For example, an increase in myopia prevalence from 19% to 20% is modelled to be accompanied by a 0.1% increase in the prevalence of high myopia from 1.55% to 1.65%-a ratio of 0.1. Conversely, an increase in myopia prevalence from 79% to 80% is predicted to result in a 1% increase in the prevalence of high myopia from 20.6% to 21.6%-a ratio of 1.0. The increase in the prevalence of high myopia compared with that of myopia as the latter increases is merely a function of the underlying nature of refractive error probability distributions and requires no further investigation as to its origin. This study shows how the prevalence of myopia and high myopia are inter-related. A widespread effort to slow myopia progression will affect the prevalence of high myopia but not myopia in general. In contrast, efforts to delay myopia onset will affect both.

Environmental Factors and Myopia: Paradoxes and Prospects for Prevention.

Prevention of myopia is now urgent, since there is an epidemic of high myopia, as well as ordinary myopia, in East Asia. The prevalence of high myopia is now around 20%, compared to about 1% in older generations. This new, acquired, high myopia has an unusual developmental pattern, sitting at around 1% up to the age of 11‐13, and then increasing over the next 10 years, presumably as a result of early onset environmental myopia progressing to high myopia. A critical unanswered question is whether this acquired high myopia carries the same pathological burden as the older genetic form. This question is generally important, because the prevalence of myopia appears to be rising in Europe and North America, and the prevalence of high myopia is probably increasing as well. Fortunately, it is now generally accepted that environmental change in educational pressures and the time that children spend outdoors must be responsible for the 3‐4‐fold increase in the prevalence of myopia in East Asia. In contrast, identified SNPs currently account for less than 5% of phenotypic variation. Recent trials based on increasing the amount of time that children spend outdoors suggest that incident myopia, and hence high myopia, can be prevented.

Epidemiology of Myopia.

The global burden of myopia is growing. Myopia affected nearly 30% of the world population in 2020 and this number is expected to rise to 50% by 2050. This review aims to analyze the impact of myopia on individuals and society; summarizing the evidence for recent research on the prevalence of myopia and high myopia, lifetime pathological manifestations of myopia, direct health expenditure, and indirect costs such as lost productivity and reduced quality of life (QOL). The principal trends are a rising prevalence of myopia and high myopia, with a disproportionately greater increase in the prevalence of high myopia. This forecasts a future increase in vision loss due to uncorrected myopia as well as high myopia-related complications such as myopic macular degeneration. QOL is affected for those with uncorrected myopia, high myopia, or complications of high myopia. Overall the current global cost estimates related to direct health expenditure and lost productivity are in the billions. Health expenditure is greater in adults, reflecting the added costs due to myopia-related complications. Unless the current trajectory for the rising prevalence of myopia and high myopia change, the costs will continue to grow. The past few decades have seen the emergence of several novel approaches to prevent and slow myopia. Further work is needed to understand the life-long impact of myopia on an individual and the cost-effectiveness of the various novel approaches in reducing the burden.

The epidemics of myopia: Aetiology and prevention

To assess the prevalence of refractive errors and associated factors in university students in urban areas of Anyang, Central China. This is a cross-sectional university-based study of 16- to 26-year-old students in China. Subjects from two universities were invited to undergo a comprehensive eye examination. Cycloplegic refraction was acquired by autorefractor with two drops of 1% cyclopentolate. The prevalence of myopia, high myopia, hyperopia, astigmatism, and anisometropia was calculated. Only data from right eyes were included in analysis. A total of 7732 eligible subjects were included, with an average age of 20.2 ± 1.4 years. Overall, the mean spherical equivalent (SE) was -2.92 ± 2.48 diopters (D). The prevalence of myopia (SE ≤ -0.50 D), emmetropia, and hyperopia (SE ≥ +0.50 D) was 83.2%, 9.5%, and 7.3%, respectively. Female sex (OR = 1.542; P < 0.001) and science and engineering students (OR = 1.219; P = 0.004) were more likely to be myopic. The prevalence of high myopia, defined using SE ≤ -5.0 D, ≤ -6.0 D, and ≤ -10.0 D, respectively, occurred in 20.2%, 11.1 %, and 0.5%. High myopia (SE ≤ -6.0 D) was statistically associated with female sex (OR = 1.202; P = 0.029) and younger age (OR = 0.896; P = 0.001). The prevalence of astigmatism (cylinder of ≤ -0.75 D) was 28.8%. Astigmatism was associated with male sex (OR = 0.824; P = 0.001) and younger age (OR = 0.925; P = 0.001). A prevalence of 83.2% for myopia and 11.1% for high myopia (SE ≤ -6.0 D) was found in central Chinese university students. In the future, this generation of university students may encounter long-term, vision-threatening effects, especially pathologic myopia.

This study aimed to investigate the awareness of high and pathological myopia among patients with high myopia. A cross‐sectional multicenter survey involving both physicians and patients was conducted between February and April 2021. The outpatient education status, doctors' expectations toward patient education, patients' awareness of high/pathological myopia, and their access to relevant knowledge were inquired, and the proportions of patients with myopia, including high and pathological myopia, were assessed. In total, the survey involved 6975 physicians and patients with myopia from 161 medical institutions in China. The prevalence of high myopia among patients was 11.3%, with 22.59% having pathological myopia. Among those with pathological myopia, 22.45% experienced high myopia complications. Approximately 48.7% of the physicians believed that patients had only a vague idea about high/pathological myopia, with certain misconceptions. Additionally, most outpatients (61.4%) had no access to specialized staff for patient education. Patients' preferences and requirements for online ophthalmology information varied based on family background, medical history, and cognition toward myopia. This study demonstrated that the awareness level among patients with myopia regarding high and pathological myopia is currently insufficient. Therefore, it is important to enhance education efforts to reduce the incidence of adverse outcomes.

PurposeTo evaluate the prevalence and risk factors of myopia in adult Korean population.MethodsPopulation-based cross-sectional data of 3,398 subjects aged 19 to 49 years was obtained using the Korea National Health and Nutrition Examination Survey 2013–2014 (KNHANES VI). Data, including refractive errors and potential risk factors were analyzed. The prevalence and risk factors of myopia, low myopia, and high myopia—defined as a spherical equivalent (SEQ) ≤ -0.5 diopters (D), -6.0 D < SEQ <-0.5 D, and SEQ ≤ -6.0 D, respectively—were evaluated.ResultsThe prevalence of myopia and high myopia were 70.6 (standard error (SE), ±1.1)% and 8.0 (SE, ±0.6)%, respectively. In multivariable analysis, younger age, higher education (≥12 years), parental myopia, lower serum 25-hydroxyvitamin D (25(OH)D) concentration (<9 ng/mL), longer time spent on near work (≥3 hours/day), and higher white blood cell (WBC) count (5–8.9 x 103) were associated with increased prevalence of both myopia and high myopia. Serum 25(OH)D concentration of ≥ 9 ng/ml was significantly associated with decreased prevalence of high myopia in participants with near work of ≥3 hours/day, although the effect was not significant in myopia and low myopia.ConclusionsThe prevalence of myopia and high myopia in Korean adults was substantially high, which increased with decreasing age. In addition to parental myopia, the serum 25(OH)D concentration, near work and inflammation reflected by WBC counts may be associated with myopia.

BackgroundThis study aimed at investigating the relationship between the weekend catch-up outdoor duration (WCOD) and prevalence of myopia among students in China.MethodsThis cross-sectional study recruited participants in 107 schools (six cities, 30 districts) from China from May to June 2021. Demographic characteristics (age, grade, sex, ethnicity, BMI, resident, and parents’ myopia), optically habits (bad writing habits, working/studying time per day, continuous working/studying time per day, and screen time per day) and outdoor duration (weekday and weekend) were obtained from questionnaire. WCOD was defined as outdoor time 1 h longer on weekends than on weekdays. Spherical equivalent (SE) of refractive error were measured with non-cycloplegic refraction. Adjusted multivariate logistic regression analysis was performed to evaluate the relationship between WCOD and prevalence of myopia.ResultsStudents with myopia had shorter WCOD compared with those without myopia (P < 0.001). Adjusted multivariate logistic regression analyses showed negative associations between WCOD and prevalence of myopia in Chinese students, especially in students with WCOD of 2–3 h (OR = 0.577, P < 0.001) and 3–4 h (OR = 0.571, P = 0.004) when the weekday outdoor duration was 0.5–1 h, as well as students with WCOD of 2–3 h (OR = 0.614, P = 0.003) when the weekday outdoor duration was 1–2 h. Similar results were observed in students with high myopia. Students with high myopia had shorter WCOD compared with those without high myopia (P = 0.001). Negative associations between WCOD and prevalence of high myopia were significant in students with WCOD of 1–2 h when the weekday outdoor duration was < 0.5 h (OR = 0.585, P = 0.007) and 0.5–1 h (OR = 0.537, P = 0.018).ConclusionOur study, for the first time, reported that a WCOD have a potential to reduce the prevalence of myopia and high myopia in Chinese students.

PurposeTo assess prevalence and associated factors of myopia and high myopia in schoolchildren in Greater Beijing.MethodsThe school-based, cross-sectional Greater Beijing School Children Myopia study was carried out in the year 2016 in 54 schools randomly selected from 15 districts in Beijing. Non-cycloplegic auto-refractometry of the right eyes was performed.ResultsThe study included 35,745 (99.4%) out of 35,968 eligible pupils with a mean age of 12.6±3.4 years (range 6–18 years). Prevalence of myopia defined as myopic refractive error of ≥-0.50 diopters (D),≥-1D,≥-6D,≥-8D and ≥-10D was 70.9%(95% confidence intervals (CI):70.5,71.4), 60.9% (95%CI:60.4,61.4), 8.6%(95%CI:8.4,8.9), 2.2%(95%CI:2.0,2.4), and 0.3% (95%CI:0.3,0.4), respectively. The frequency of high myopia (≥-6D, ≥-8D, ≥-10D) increased from 1.5% (95%CI:1.0,2.0), 0.4% (95%CI:0.1,0.6) and 0.1% (95%CI:0.00,0.02), respectively in 10-year-olds to 19.4% (95%CI:17.3,21.6), 5.2% (95%CI:4.0,6.4) and 0.9% (95%CI:0.4,1.5), respectively, in 18-year-olds. Mean refractive error in the 18-year-olds was -3.74±2.56D (median:-3.63D;range:-19.6D to + 6.25D). Higher prevalence of high myopia (≥-6D and ≥-8D) was correlated (all P<0.001) with older age (OR:1.18, and 1.15, respectively), female gender (OR: 1.44 and 1.40, respectively), higher body mass index (OR: 1.02 and 1.03, respectively), taller body height (OR: 1.03 and 1.02, respectively), urban region of habitation (OR: 1.26 and 1.33, respectively) and higher school type (OR:1.57 and 2.22, respectively). Prevalence of severe high myopia (≥-10D) was associated only with older age (P<0.001; OR: 1.44; 95%CI: 1.31, 1.59) but not with any education-related parameter such as higher school type (P = 0.48), urban region of habitation (P = 0.07) or female gender (P = 0.37).ConclusionIn this most recent survey, prevalence of high myopia (≥-6D:19.4%;≥-8D:5.2%;≥-10D:0.9%) in 18-year-old school children was higher than in previous surveys from mainland China. In contrast to minor high myopia and moderate high myopia (defined as myopic refractive error of <-10D), severe high myopia (myopic refractive error ≥-10D) was not strongly correlated with educational parameters.

PurposeTo evaluate prevalence and associated factors for myopia in high school students in Beijing.MethodsGrade 10 and 11 high school students were randomly selected from nine randomly selected districts of Beijing. The students underwent non-cylcoplegic auto-refractometry and an interview.ResultsOut of 4798 eligible students, 4677 (93.4%) students (mean age:16.9±0.7years;range:16–18 years) participated. Mean refractive error of right eyes and left eyes was −2.78±2.29 diopters and −2.59±2.50 diopters, respectively. Prevalence of myopia (defined as ≤ −1.00 diopters in the worse eye) was 80.7% (95% Confidence Interval (CI): 79.6–81.8%). Out of 3773 students with myopia, 1525 (40.4%) wore glasses daily. In multiple logistic regression analysis, a higher prevalence of myopia was associated with female sex (odds ratio (OR) = 1.31;95%CI:1.11–1.55), Han ethnicity (OR = 1.64;95%CI:1.28–2.11), attending key schools (OR = 1.48;95%CI:1.24,1.77), higher family income (OR = 1.37;95%CI:1.09–1.71), longer time spent for near work (OR = 1.43;95%CI:1.06–1.93), shorter near work distance (OR = 1.87;95%CI:1.55–2.26), lower frequency of active rest during studying (OR = 1.40;95%CI:1.16–1.70), and parental myopia (OR = 2.28;95%CI:1.80–2.87). The interaction between distance from near work and time spent for near work was statistically (P = 0.03) significant. In multiple logistic regression analysis, higher prevalence of high myopia (≤-6.0 diopters) was associated with studying in key schools (OR = 1.38;95%CI:1.05,1.81), lower frequency of active rest during studying (OR = 1.40;95%CI:1.09,1.79), and a higher number of myopic parents (OR = 2.66;95%CI:2.08,3.40).ConclusionsA prevalence of about 80% for myopia and a prevalence of about 10% for high myopia in students aged 16 to 18 years and attending classes of grade 10 and 11 in a Chinese metropolitan region is another example of the high prevalence of moderate and high myopia in metropolitan areas of China. With this young myopic generation getting older, myopia as cause for visual impairment and blindness may further increase in importance. Future studies may address whether active rests during studying with looking into the distance are preventive against myopia development or progression.