The increasing prevalence of myopia in junior high school students in the Haidian District of Beijing, China: a 10-year population-based survey

High prevalence of myopia in children and their parents in Hong Kong Chinese Population: the Hong Kong Children Eye Study

PURPOSE

To determine the myopia prevalence in Hong Kong Chinese children and their parents.

METHODS

It was a population-based cross-sectional study. A total of 4257 children aged 6-8 years, and 5880 parents were recruited in the Hong Kong Children Eye Study. Cycloplegic autorefraction was measured for children; and non-cycloplegic autorefraction for parents. Parental educational level, children's outdoor time, and near work were collected by validated questionnaires.

RESULTS

In children aged 6-8 years, 25.0% were myopic, and among them, 12.7% for the 6-year-olds, 24.4% for the 7-year-olds and 36.1% for the 8-year-old. About 0.7% of children aged 8 years were high myopia. In all age groups, boys (their myopia rate: 13.9% at 6 years, 26.7% at 7 years, and 38.3% at 8 years) were more myopic than girls (11.3% at 6 years, 22.0% at 7 years, 33.4% at 8 years). Among parents, 72.2% were myopic (mother, 73.2%; father, 70.7%) and 13.5% high myopia (mother, 12.8%; father, 14.5%). It was observed that prevalence decreased with ages and increased with education level.

CONCLUSION

There is a strikingly high prevalence of myopia in Hong Kong children aged 6-8, much higher than that of other regions of China. Of note, the prevalence of children was similar to that in 15 years ago. Furthermore, the myopia prevalence of parents is high, and it had already increased in this cohort. Prevention of childhood myopia is important, likewise for visual complications from high myopia in adults.

Low physical activity and higher use of screen devices are associated with myopia at the age of 16-17 years in the CCC2000 Eye Study

PURPOSE

To determine the myopia prevalence in a Danish cohort aged 16-17 years and its relation to physical activity and use of screen-based electronic devices.

METHODS

The Copenhagen Child Cohort 2000 Eye Study is a prospective, population-based, observational study. Information about use of screen devices and physical activity was obtained using questionnaires. Myopia was defined as non-cycloplegic subjective spherical equivalent refraction ≤-0.50 D in right eye.

RESULTS

We included 1443 participants (45% boys) with a median age (±IQR) of 16.6 years (±0.3). The prevalence of myopia was 25% (CI95% 23-28, n = 360) with no differences between sexes (p = 0.10). The odds ratio (OR) for myopia was 0.57 (CI95% 0.42-0.76, p = 0.0002) in participants physically active 3-6 hr/week (n = 502) and 0.56 (CI95% 0.42-0.76, p = 0.0002) if active >6 hr/week (n = 506), both compared with participants physically active <3 hr/week (n = 396). The use of screen devices >6 hr/day was associated with increased OR for myopia compared with screen device use <2 hr/day in both weekdays (OR = 1.95, CI95% 1.16-3.30, p = 0.012) and weekends (OR = 2.10, CI95% 1.17-3.77, p = 0.013).

CONCLUSION

In this cohort of healthy 16-17-year olds, lower physical activity and more use of screen devices contributed significantly to the observed 25% prevalence of myopia with a roughly doubled risk of having myopia if physically active <3 hr/week or if using screen devices >6 hr/day. Our results support physical activity being a protective factor and near work a risk factor for myopia in adolescents.

The Prevalence of Myopia and Factors Associated with It Among Secondary School Children in Rural Vietnam

Purpose

To assess the prevalence of myopia and associated factors among secondary school children in a rural area of Vietnam.

Methods

A school-based cross-sectional study of children in grades six to nine was conducted in four secondary schools in Hoang Mai town, Nghe An Province, Vietnam, during December 2018 and January 2019. The status of myopia was defined as a spherical equivalent objective refractive error of −0.50 D or worse in either eye. A case–control study was conducted to explore factors associated with myopia, where children with myopia were considered to be cases, and children without myopia were considered to be controls. Factors associated with myopia were analyzed using univariate and multivariate logistic regression.

Results

The prevalence of myopia among secondary school children was 14.2% (95% CI: 12.7–15.7%) and tended to increase with grade, from 10.5% in grade six to 17.7% in grade nine. Myopia prevalence in girls was significantly higher than in boys. Factors associated with myopia were a mother with a college/university education (OR = 2.5, 95% CI = 1.2–5.3), parents who wore spectacles (OR = 2.0, 95% CI = 1.1–3.8), distance from near work (OR = 5.2, 95% CI = 3.5–7.9), and taking breaks after 30 minutes of continued reading (OR = 1.6, 95% CI = 1.1–2.5). However, there were inverse associations with myopia for children belonging to the wealthiest households (OR = 0.2, 95% CI = 0.1–0.5) and time spent performing outdoor activities (OR = 0.6, 95% CI = 0.4–0.9).

Conclusion

Our study showed that the prevalence of myopia is considerable among secondary children in rural areas of Vietnam. The prevalence of myopia tended to increase among children in higher grade levels. Thus, appropriate interventions should be developed and conducted to deal with the issue of school-age myopia.

Surgical treatment for type II macular hole retinal detachment in pathologic myopia

To observe the effectiveness and complications of inverted internal limiting membrane insertion through 25-G minimally invasive vitrectomy assisted with autologous blood adhesion fixation and combined with gas tamponade type-II macular hole retinal detachment in pathologic myopia.This was a retrospective study. The best-corrected visual acuity, intraocular pressure, macular hole closure, retinal reattachment, and systemic and ocular adverse events were observed.Twenty-three eyes were operated. Best-corrected visual acuity before surgery and at 3 and 6 months were 2.25 ± 0.47, 1.85 ± 0.32, and 1.32 ± 0.36 LogMAR (P < .001). On days 2 to 5, all the retinas reattached, and the macular holes closed. On days 5 to 9, 5 eyes showed increased intraocular pressure. At 2 and 4 months, 2 eyes showed retinal detachment recurrence. No serious systemic or ocular adverse events were observed.This surgical technique showed clinical benefits and no significant complications. Clinical trials are necessary to confirm efficacy and safety.

Evaluating the myopia progression control efficacy of defocus incorporated multiple segments (DIMS) lenses and Apollo progressive addition spectacle lenses (PALs) in 6- to 12-year-old children: study protocol for a prospective, multicenter, randomized controlled trial

Background

Myopia is increasing in prevalence and is currently recognized as a significant public health issue worldwide, particularly in China. Once myopia develops, appropriate clinical interventions need to be prescribed to slow its progression. Currently, several publications indicate that myopic defocus (MD) retards eye growth and myopia progression. However, no clinical trials have compared the outcomes of different MD spectacle lenses in the same observational group, especially in mainland China. The aim of the present study is to compare the myopia control efficiency of two different MD spectacle lenses: defocus incorporated multiple segments (DIMS) lenses and Apollo progressive addition lenses (PALs).

Methods

The trial is designed as a 3-year, prospective, randomized, multicenter clinical trial of schoolchildren treated with DIMS lenses and PALs. A total of 600 Chinese primary school children aged 6–12 years will be recruited, and each group is intended to include 300 subjects. The inclusion criteria are myopia between − 1.00 and − 5.00 diopters and astigmatism ≤ 1.50 diopters. The follow-up time points will be 1 month (m), 3 m, 6 m, 12 m, 18 m, 24 m, 30 m, and 36 m. The primary outcome will be determined by the difference between the two groups in cycloplegic spherical equivalent refraction between baseline and the last follow-up visit. The secondary outcome is the axial length, and the exploratory outcomes include ocular biometric measures, peripheral refraction, binocular vision, accommodation, compliance, and the results of questionnaires related to wearing experiences.

Discussion

The present study will be the first randomized controlled trial in myopic primary school children treated with DIMS lenses and PALs in China. The results will indicate whether and how much different MD mechanisms retard myopia progression and axial elongation. In addition, the comparison will provide information on the clinical efficacy and safety of DIMS lenses and PALs, including information related to wearing experiences and visual function.

Trial registration

Chinese Clinical Trial Registry (ChiCTR), ChiCTR1900025645. Registered on 3 September 2019. http://www.chictr.org.cn/showproj.aspx?proj=42927.

Morphologic and biochemical changes in the retina and sclera induced by form deprivation high myopia in guinea pigs

BACKGROUND

To study the morphologic and biochemical changes in the retina and sclera induced by form deprivation high myopia (FDHM) in guinea pigs and explore the possible mechanisms of FDHM formation.

METHODS

Forty 3-week-old guinea pigs were randomized into the blank control (Group I, 20 cases) and model groups (20 cases). In the model group, the right eyes of the guinea pigs were sutured for 8 weeks to induce FDHM (Group II) and the left eyes were considered a self-control group (Group III). The refractive errors were measured with retinoscopy. The anterior chamber depth (AC), lens thickness (L), vitreous chamber depth (V) and axial length (AL) were measured using ultrasonometry A. Retinal and scleral morphology and ultrastructural features were observed with light and electron microscopy. The malondialdehyde (MDA) content and superoxide dismutase (SOD) activity in the retina and sclera were detected with a chemical colorimetric assay.

RESULTS

After 8 weeks of stitching, the refractive errors of Group II changed from (+ 3.59 ± 0.33) D to (- 7.96 ± 0.55) D, and these values were significantly higher than those of Group I (+ 0.89 ± 0.32) D and Group III (- 0.55 ± 0.49) D (P < 0.05). The vitreous chamber depth (4.12 ± 0.13) mm and axial length (8.93 ± 0.22) mm of Group II were significantly longer than those of Group I [(3.71 ± 0.23) mm and (7.95 ± 0.37) mm, respectively] and Group III [(3.93 ± 0.04) mm and (8.01 ± 0.15) mm, respectively] (P < 0.05). With the prolongation of form deprivation (FD), the retina and scleral tissues showed thinning, the ganglion cell and inner and outer nuclear layers of the retina became decreased, and the arrangement was disordered. In Group II, the SOD activity was significantly lower than that in Group I and Group III; the MDA content was significantly higher than that in Group I and Group III. The differences were statistically significant (P < 0.05).

CONCLUSIONS

These findings suggested that in the FDHM guinea pigs model, the refractive errors, the vitreous chamber depth, and axial length increased significantly with prolongation of monocular FD time, and morphological structural changes in the retina and sclera were observed. Oxygen free radicals might participate in the formation of FDHM.

A Serial Cross-Sectional Analysis of the Prevalence, Risk Factors and Geographic Variations of Reduced Visual Acuity in Primary and Secondary Students from 2000 to 2017 in Hong Kong

Background: We would like to investigate the prevalence trend, potential risk factors and geographic features of reduced visual acuity (VA) in primary and secondary schoolchildren of Hong Kong. Methods: This was a serial cross-sectional study using historical data of schoolchildren aged 6 to 15 years from the annual health checks conducted at Student Health Service Centers across Hong Kong, for the school years of 2000/2001 to 2016/2017. Results: The prevalence of reduced VA increased from 49.23% (95% CI, 48.99-49.47) in 2000/2001 to 54.34% (95% CI, 54.10-54.58) in 2011/2012 but decreased to 51.42% (95% CI, 51.17-51.66) in 2016/2017. Girls were less susceptible than boys at age 6-7 (and in grade primary 1-2), but more susceptible at older ages. The prevalence in junior grades increased while the risk effect of grade reduced over the past 17 years. Geographic variation on the risk for reduced VA existed and spatial autocorrelation was positive. The difference in prevalence of reduced VA between Hong Kong and mainland China has decreased in recent years. Cross-border students living in mainland China were associated with a lower risk for reduced VA. Conclusions: Further study was proposed to investigate the environmental association between students living in and outside Hong Kong with the prevalence of reduced VA. Multi-level research should also be conducted to investigate the influence of compositional and contextual factors on the prevalence of reduced VA.

A review on the epidemiology of myopia in school children worldwide

Background

Due to high prevalence myopia has gained importance in epidemiological studies. Children with early onset are at particular risk of complications associated with myopia, as progression over time might result in high myopia and myopic macular degeneration. Both genetic and environmental factors play a role in the increasing prevalence of myopia. The aim of this study is to review the current literature on epidemiology and risk factors for myopia in school children (aged 6–19 years) around the world.

Main body

PubMed and Medline were searched for the following keywords: prevalence, incidence, myopia, refractive error, risk factors, children and visual impairment. English language articles published between Jan 2013 and Mar 2019 were included in the study. Studies were critically reviewed for study methodology and robustness of data. Eighty studies were included in this literature review.

Myopia prevalence remains higher in Asia (60%) compared with Europe (40%) using cycloplegic refraction examinations. Studies reporting on non-cycloplegic measurements show exceptionally high myopia prevalence rates in school children in East Asia (73%), and high rates in North America (42%). Low prevalence under 10% was described in African and South American children. In recent studies, risk factors for myopia in schoolchildren included low outdoor time and near work, dim light exposure, the use of LED lamps for homework, low sleeping hours, reading distance less than 25 cm and living in an urban environment.

Conclusion

Low levels of outdoor activity and near work are well-established risk factors for myopia; this review provides evidence on additional environmental risk factors. New epidemiological studies should be carried out on implementation of public health strategies to tackle and avoid myopia. As the myopia prevalence rates in non-cycloplegic studies are overestimated, we recommend considering only cycloplegic measurements.

Prevalence of myopia and vision impairment in school students in Eastern China

BACKGROUND

Prevention of myopia has become a public health priority in China. This study is to investigate the prevalence of myopia and vision impairment, and their associated factors in school students in eastern China.

METHOD

In this cross-sectional school-based study of 4801 students from 16 schools ranging from kindergarten to high school, students underwent refraction using non-cycloplegic autorefractor and visual acuity testing using logMAR chart with tumbling E. Myopia was defined as spherical equivalent (SPHE) ≤ - 0.5 diopter (D) and uncorrected visual acuity (UCVA) 20/25 or worse. High myopia was defined as SPHE ≤ - 6.0 D and UCVA 20/25 or worse. Vision impairment was defined as UCVA 20/40 or worse. Logistic regression models were used to determine factors associated with myopia and vision impairment.

RESULTS

Among 4801 children (55% male) with mean age (standard deviation) 12.3 (3.8) years, 3030 (63.1, 95% CI: 61.7-64.5%) had myopia, 452 (9.4, 95% CI: 8.6-10.3%) had high myopia, and 2644 (55.1, 95% CI, 53.7-56.5%) had vision impairment. The prevalence rate of myopia increased with grade in a non-linear manner, 12% in kindergarten, 32% in grade 2, 69% in grade 5, and approximately 90% by grade 10 or above. The prevalence rate of high myopia was relatively low in grade 4 or below (< 1.5%), 4-7% in grade 5 to 7, 13-15% in grade 8-9, and > 20% in grade 10 to 12. The prevalence rate of vision impairment was 4% in kindergarten, 37% in elementary school, 77% in middle school and 87% in high school students. Higher grade (p < 0.0001), female (p < 0.0001) and higher school workload (p = 0.007) were independently associated with higher prevalence rates of myopia and vision impairment, while higher grade (p < 0.0001) and higher school workload (p < 0.0001) were independently associated with higher prevalence of high myopia.

CONCLUSION

Prevalence of myopia and vision impairment was high among Chinese school students and increased with grade in a non-linear manner, reaching alarming high in high school students accompanied by high prevalence of high myopia. Increasing study burden on school students at younger age plays an important role on the higher prevalence rate of myopia and vision impairment.

Efficacy and Safety of 1% Atropine on Retardation of Moderate Myopia Progression in Chinese School Children

Background: To evaluate the long-term efficacy and safety of topical 1% atropine for retarding moderate myopia. Methods: A randomized, controlled study evaluating atropine and placebo in 660 Chinese children. Patients received drops q1month for 24 months, then q2month for 12 months, followed by no drops for 12 months. Spherical equivalent, axial length, intraocular pressure and atropine-related side effects were examined at 6, 12, 24, 36 and 48 months for all children. Results: Spherical equivalent, myopic progression, axial length augmentation, and progression rate were significantly reduced in the atropine group than those in the placebo group (all P<0.05), indicating that 1% atropine effectively retarded myopia. Moreover, myopic rebound and adverse effects of 1% atropine were eliminated by gradual withdrawal and elimination of 1% atropine. Furthermore, pupil size, near visual acuity, and amplitude of accommodation returned to pretreatment levels after withdrawal of atropine. Conclusion: Topical 1% atropine periodically and alternatively in phase I with gradual reduction in phase II and final withdrawal in phase III may effectively improve atropine efficacy, retard moderate myopia, reduce atropine side effects, minimize myopic rebound, and increase compliance of children simultaneously.

Current Prevalence of Myopia and Association of Myopia With Environmental Factors Among Schoolchildren in Japan

Importance

Given the estimates of increasing prevalence of myopia, especially in Asia, it is important to determine the current prevalence of myopia among populations of schoolchildren in Japan.

Objective

To investigate the current prevalence rate of myopia and the association between environmental factors and myopia in Japanese schoolchildren.

Design, Setting, and Participants

This cross-sectional study assessed 1478 participants, including 726 elementary school students and 752 junior high school students, at 2 schools in Tokyo, Japan, who underwent eye examinations from April 1 to May 31, 2017, that included measurement of the refractive errors by autorefractometry with noncycloplegic refraction and ocular biometric factors. After excluding those who had been treated with atropine or orthokeratology (n = 11), had a history of eye disease (n = 2), had no parental consent (n = 41), and were absent (n = 8), 1416 schoolchildren were analyzed.

Main Outcomes and Measures

The primary outcome was the prevalence of myopia and high myopia. Secondary outcomes were environmental factors that were associated with myopia.

Results

A total of 1416 schoolchildren (mean [SD] age, 10.8 [2.7] years; 792 [55.9%] male) were studied. The prevalence rates of myopia (spherical equivalent ≤-0.5 diopters [D]) were 76.5% (95% CI, 73.4%-79.7%) among the elementary school students and 94.9% (95% CI, 93.3%-96.5%) among the junior high school students. The prevalence rates of high myopia (spherical equivalent ≤-6.0 D) were 4.0% (95% CI, 2.5%-5.4%) among the elementary school students and 11.3% (95% CI, 8.8%-13.7%) among the junior high school students. The prevalence rates of high myopia classified based on axial length of 26.0 mm or longer were 1.2% (95% CI, 0.4%-2.0%) among elementary school students and 15.2% (95% CI, 12.5%-17.8%) among junior high school students. Multiple regression analysis showed that higher-order aberrations and dry eye disease were associated with refractive error in elementary school students (spherical aberration: β = 6.152; 95% CI, 3.161-9.143; P < .001; dry eye disease: β = -0.626; 95% CI, -1.189 to -0.063; P = .03) and with axial length in junior high school students (spherical-like aberration: β = 26.546; 95% CI, 18.708-34.385; P < .001; dry eye disease: β = 0.354; 95% CI, 0.131-0.578; P < .002).

Conclusions and Relevance

Although the use of noncycloplegic autorefraction with a cutoff of -0.50 D could lead to overestimation of results, these findings suggest that the current prevalence rates of myopia among elementary and junior high school students in Asia are high, especially if the results from these 2 schools are generalizable to all schoolchildren in Japan and Asia.

Refractive Change and Incidence of Myopia Among A Group of Highly Selected Senior High School Students in China: A Prospective Study in An Aviation Cadet Prerecruitment Class

Purpose

To assess the incidence rate of myopia, refractive change, and the effects of influencing factors on a group of highly selected senior high school students in an Aviation Cadet prerecruitment class in China.

Methods

A total of 800 nonmyopic, male, Grade 9 students aged 14- to 16-years old with cycloplegic refraction of -0.25 or greater diopters (D) to 1.75 D or less in both eyes were enrolled in May 2016. During their senior high school studies, students had one 20-minute physical training period a day, and they were encouraged to participate in outdoor activities during class recess without any time limits. The first follow-up was 8 months after enrollment when they were in Grade 10, and the second follow-up was 1 year after the first follow-up when they were in Grade 11. Comprehensive ocular examinations and a detailed questionnaire, which included questions about outdoor activity time, parental myopia, and near work, were completed at each follow-up.

Results

The average spherical equivalent refraction (SER) of the right eyes was 0.39 ± 0.44 D at baseline, 0.16 ± 0.41 D at the first follow-up, and -0.10 ± 0.38 D at the second follow-up. The cumulative refractive change was -0.50 D (95% confidence interval [CI], -0.53 to -0.47). The cumulative incidence rate of myopia was 15.5% (124/800). Incident myopia was significantly associated with outdoor activity for more than 1 versus less than 0.5 hr/d (odds ratio [OR] = 0.272, 95% CI, 0.132-0.560), baseline refraction (OR = 0.079, 95% CI, 0.041-0.153), maternal myopia (OR = 2.251, 95% CI, 1.160-4.368), longer class time (OR =3.215, 95% CI, 1.088-9.499), frequent, continuous, and long time reading/writing (OR = 1.620, 95% CI, 1.022-2.570), and shorter reading/writing distance (OR = 1.828, 95% CI, 1.065-3.140). In multiple linear regression model, having outdoor activity for more than 1 hr/d was protective from cumulative SER decrease. A higher baseline refraction together with longer reading/writing time, frequent, continuous, and longtime reading/writing, and shorter reading/writing distance were risk factors for SER decrease.

Conclusions

In this cohort of highly selected, nonmyopic students, longer outdoor activity time was a protective factor for both incident myopia and refractive change of myopic shift. The risk factors for incident myopia included lower hyperopic baseline refraction, more near work, and maternal myopia. The risk factors for refractive change of myopic shift included more hyperopic baseline refraction and more near work.

IMI - Clinical Myopia Control Trials and Instrumentation Report

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

Analysis of Scientific Collaboration Networks among Authors, Institutions, and Countries Studying Adolescent Myopia Prevention and Control: A Review Article

BACKGROUND

Studies related to the prevention and control of myopia in adolescents have increased rapidly, but only a few have measured the levels of scientific collaboration among authors, institutions and countries in this field. Thus, in this study, we aimed to reveal the status and levels of scientific collaboration in this field.

METHODS

The research population included all published papers in the field of adolescent myopia prevention and control indexed in the Web of Science databases from 1997-2016. The co-authorship networks were drawn using SATI (Statistical Analysis Toolkit for Informetrics), Ucinet and VOS viewer (Visualisation of Similarities viewer). Active authors and some measures of co-author network, including degree centrality, closeness, betweenness, density and diameter, were also assessed.

RESULTS

Overall, 610 records were obtained, and a number of publications developed through an increase in different collaboration types, with cooperation among authors and institutions as the most apparent ones. The top ten active authors and institutions were identified. The density of cooperative networks of the top 70 authors and the first 69 institutions were 0.043 and 0.011, respectively, with corresponding diameters of five and six, respectively. Seven distinct clusters formed the cooperation network among 38 countries. The top three clusters were centered in China, the United States and Australia, also identified as the most productive countries.

CONCLUSION

The flow of information is slow and the collaboration among authors and institutions in the network are not close enough. Thus, multiple collaboration types should be encouraged in this field, especially among countries.

Gene expression in response to optical defocus of opposite signs reveals bidirectional mechanism of visually guided eye growth

Myopia (nearsightedness) is the most common eye disorder, which is rapidly becoming one of the leading causes of vision loss in several parts of the world because of a recent sharp increase in prevalence. Nearwork, which produces hyperopic optical defocus on the retina, has been implicated as one of the environmental risk factors causing myopia in humans. Experimental studies have shown that hyperopic defocus imposed by negative power lenses placed in front of the eye accelerates eye growth and causes myopia, whereas myopic defocus imposed by positive lenses slows eye growth and produces a compensatory hyperopic shift in refractive state. The balance between these two optical signals is thought to regulate refractive eye development; however, the ability of the retina to recognize the sign of optical defocus and the composition of molecular signaling pathways guiding emmetropization are the subjects of intense investigation and debate. We found that the retina can readily distinguish between imposed myopic and hyperopic defocus, and identified key signaling pathways underlying retinal response to the defocus of different signs. Comparison of retinal transcriptomes in common marmosets exposed to either myopic or hyperopic defocus for 10 days or 5 weeks revealed that the primate retina responds to defocus of different signs by activation or suppression of largely distinct pathways. We also found that 29 genes differentially expressed in the marmoset retina in response to imposed defocus are localized within human myopia quantitative trait loci (QTLs), suggesting functional overlap between genes differentially expressed in the marmoset retina upon exposure to optical defocus and genes causing myopia in humans. These findings identify retinal pathways involved in the development of myopia, as well as potential new strategies for its treatment.

The worldwide prevalence of myopia is predicted to increase from the current 23% to about 50% in the next three decades. Although much effort has been directed towards elucidating the mechanisms underlying refractive eye development and myopia, treatment options for myopia are mostly limited to optical correction, which does not prevent progression of myopia nor the pathological blinding complications often associated with the disease. Several experimental optics-based treatments have had only limited effect on myopia progression, and currently available drug treatments are limited and the mechanisms of action are not well understood. The development of safe and effective pharmacological treatments for myopia is urgently needed to prevent the impending myopia epidemic. The main obstacles that prevent the development of anti-myopia drugs are the uncertainties regarding the mechanisms controlling eye growth and optical development, including the molecular signaling pathways underlying it. In this study, we show that, contrary to the conventional thinking that myopic and hyperopic defocus trigger opposite changes in the same genes and pathways to guide postnatal eye growth, defocus of opposite signs affect eye growth via largely distinct retinal pathways. Knowing that myopic and hyperopic defocus signals drive eye growth in opposite directions and propagate via different pathways provides a framework for the development of new anti-myopia drugs. Myopia can be controlled pharmacologically by stimulating pathways underlying the retinal response to positive lenses and/or by suppressing pathways underlying the retinal response to negative lenses.

The increasing prevalence of myopia and high myopia among high school students in Fenghua city, eastern China: a 15-year population-based survey

BACKGROUND

Myopia is the leading cause of preventable blindness in children and young adults. Multiple epidemiological studies have confirmed a high prevalence of myopia in Asian countries. However, fewer longitudinal studies have been performed to evaluate the secular changes in the prevalence of myopia, especially high myopia in China. In the present study, we investigated trends in the prevalence of myopia among high school students in Fenghua city, eastern China, from 2001 to 2015.

METHODS

This was a population-based, retrospective study. Data were collected among 43,858 third-year high school students. Noncycloplegic autorefraction was used to determine refractive error, which was defined as low myopia, moderate myopia, high myopia and very high myopia according to the spherical equivalent from the worse eye of each participant. The prevalence of myopia was calculated and the annual percentage change (APC) was used to quantify the time trends. All analyses were conducted using the SPSS, Stata and Graphpad Prism software.

RESULTS

From 2001 to 2015, the prevalence of overall myopia increased from 79.5% to 87.7% (APC =0.59%), with a significant increase of moderate myopia (38.8% to 45.7%, APC = 0.78%), high myopia (7.9% to 16.6%, APC = 5.48%) and very high myopia (0.08% to 0.92%, APC = 14.59%), while the prevalence of low myopia decreased from 32.7% to 24.4% (APC = - 1.73%). High myopia and very high myopia contributed the major part of the increasing trend of myopia prevalence (contribution rate 27.00% and 69.07%, respectively).

CONCLUSIONS

During the 15-year period, there was a remarkable increase in the prevalence of high and very high myopia among high school students, which might become a serious public health problem in China for the next few decades.

Frequent mutations of RetNet genes in eoHM: Further confirmation in 325 probands and comparison with late-onset high myopia based on exome sequencing

In our previous study, potential pathological mutations of RetNet genes were detected in 23.8% (71/298) of probands with early-onset high myopia (eoHM), based on whole exome sequencing (WES). The current study aimed to confirm this finding in an additional 325 probands with eoHM and to clarify its specificity by comparison of 195 probands with late-onset high myopia (loHM). Variants in the 234 RetNet genes were selected from whole-exome sequencing data and were filtered using multistep bioinformatics analyses. Potential pathological variants in 33 genes were detected in 76 of 325 (23.4%) probands with eoHM and 14 of 195 (7.2%) probands with loHM. Thirty-five of the 76 (46.1%) probands with eoHM had mutations in COL2A1, COL11A1, RPGR, and CACNAIF, while only 2/14 (14.3%) probands with eoHM were detected. The mutation frequency and spectrum of RetNet genes in the 325 probands with eoHM were similar to our previous study but were significantly different in 195 probands with loHM (P = 2 × 10^-6 and 0.04). Data from eoHM and loHM strongly suggest that a significant proportion of eoHM is caused by mutations in RetNet genes. These results also provide initial genetic evidence that eoHM is different from loHM. The presence of mutations in 7.2% probands with loHM raises questions about pathogenicity and the variable manifestation of some mutations. The functional studies of the mutations in question and more extensive investigations of related phenotypes in the mutation carriers and their family members may provide valuable information to address these questions.