Ethnicity-specific prevalences of refractive errors vary in Asian children in neighbouring Malaysia and Singapore

Ethnicity and refractive errors in Peruvian children aged 7-11 years: A five-year analysis of the Demographic and Health Survey

OBJECTIVE

To assess the association between ethnicity and self-reported refractive errors (REs) among Peruvian children aged 7-11 years.

MATERIALS AND METHODS

We conducted a cross-sectional study incorporating a secondary data analysis of 2017-2021 data from the Peruvian Demographic and Health Survey (DHS). REs and ethnicity were obtained from focal child's mother's report. Four outcomes were assessed: hyperopia, myopia, astigmatism and any RE. We included potential confounders, such as age, sex, wealth index, area of residence, region of origin, frequency of watching TV and watching screens at less than 30 cm distance. Generalised linear models with the Poisson family and log link function were used to calculate crude prevalence ratio and adjusted prevalence ratio (aPR) with 95% confidence intervals (95% CI).

RESULTS

Data from a total of 52,753 children were included. The prevalence of RE in children aged 7-11 years was 10.90% (95% CI 10.49-11.33), of which 5.19% were hyperopia, 3.35% myopia and 2.36% astigmatism. Those of the Aymara ethnicity were less likely to suffer from any RE and astigmatism (aPR = 0.68, 95% CI 0.46-0.99, p = 0.046; aPR = 0.70, 95% CI 0.53-0.92, p = 0.012, respectively), Members of Amazon groups were more likely to have hyperopia (aPR = 1.95, 95% CI 1.14-3.36, p = 0.015) and Quechuas were more likely to have myopia (aPR =1.29, 95% CI 1.02-1.62, p = 0.028), where all were compared to Mestizos.

CONCLUSION

About 1 in 10 Peruvian children suffer from a RE. The most frequent RE in this study was hyperopia. Ethnic differences were seen in the frequency of RE.

Prevalence and associated factors of myopia among school students in Shenyang, China: a cross-sectional study

Background

In recent years, the prevalence of myopia has increased significantly and caused great concern. Nevertheless, an estimate of myopia in the student population in Shenyang, Liaoning Province, China is still lacking. This study aims to determine the prevalence of myopia among students in Shenyang and investigate the associated factors affecting myopia development.

Methods

Standard logarithmic visual acuity chart and automatic computerized optometry under non-ciliary muscle paralysis were used to test the students' naked visual acuity of their right and left eyes. The included students were organized to fill in questionnaires on WeChat to collect the factors affecting myopia.

Results

A total of 34,644 students with a median age of 11.9 years were examined, including 17,563 males and 17,081 females. The overall prevalence of myopia was 60%, with a prevalence of 45% for mild myopia, 13% for moderate myopia, and 1.9% for high myopia. The sex, high educational stage, family history of myopia, doing homework after school or reading and writing for more than 2 h were associated with a higher risk of myopia, while doing eye exercises twice a day or more, going outdoors during recess, reading and writing with eyes more than one foot from books, and sleeping more than 8 h a day were associated factors for preventing myopia. The associated factors influencing myopia vary among different subgroups.

Conclusion

The prevalence of myopia in Shenyang is at a high level. In addition to sex, high educational stage and genetic factors, environmental factors including length of eye usage, eye exercises, outdoor activities, eye working distance, and sleep duration are associated with myopia prevalence. Therefore, it is recommended that the occurrence and development of myopia can be prevented by controlling the above environmental factors.

Effect of Contrast Polarity Towards Eye Fixation Rates When Reading On Smartphone

This study is conducted to investigate the effect of contrast polarity towards eye fixation patterns when reading text on a smartphone in bright and dark conditions involving the effects when reading on a smartphone such as in real-life situations. The number of fixations and duration of fixation showed no statistically significant difference (p=0.160 and 0.099 respectively). However, emmetropic subjects showed a higher result in bright conditions compared to myopic subjects (p=0.046). This concludes that emmetropic eye movement efficiency seems superior, possibly due to lower spherical order aberration as pupil size decreases in bright illumination.

Prevalence and Patterns of Refractive Errors in Children and Young Adults in an Urban Region in South India: the Hyderabad Eye Study

PURPOSE

To determine the prevalence of refractive error (RE) and associated risk factors for myopic refractive errors in children and young adults from the urban region of Hyderabad, South India.

METHODS

Four thousand sixty-five (4,065) participants aged 6-22 years were enrolled and examined in this cross-sectional study conducted from October 2013 to January 2015. Participants were enrolled from a random sample of schools and universities in regions representative of urban Hyderabad. RE was determined using cycloplegic autorefraction. The association of demographic factors such as age, gender, and socio-economic category (SEC) (low/mid/high) with myopia was explored with logistic regression with robust standard error.

RESULTS

Of the total participants, 2,259 were children aged 6-15 years and 1,806 were adolescents and young adults aged 16-22 years. Overall prevalence of myopia, high myopia (≤ -5.00D and ≤ -6.00 D), hyperopia, emmetropia, and astigmatism was 29.8% (95% CI: 26.0% to 33.6%, n = 1,216), 2.9% (95% CI: 1.9% to 3.9%, n = 120), 1.1% (95%CI: 0.7% to 1.5%, n = 46), 14.7% (95% CI: 12.4% to 17.0%, n = 599), 46.9% (95% CI: 43.7% to 50.1%, n = 1913) and 8.6% (95% CI: 7.4% to 9.9%, n = 352) respectively. A strong correlation existed between age and prevalence of myopia (R² = 0.88, p < .001) and high myopia (R² = 0.71, p < .001). Children from schools of low SEC (34.7%) had higher prevalence of myopia compared to the mid SEC (16.8%) (p = .043).

CONCLUSION

Myopia was the most prevalent refractive error and increased with age in this urban population. More myopia was observed in schools of low SEC.

Comparison of vision-related quality of life between wearing Orthokeratology lenses and spectacles in myopic children living in Kuala Lumpur

PURPOSE

There are limited reports available on the impact of wearing Orthokeratology (ortho-K) lenses on the quality of life of Asian children. This study evaluated and compared vision-related quality of life (VRQoL) between myopic children wearing ortho-K lenses and single-vision spectacles (SVSs), living in Kuala Lumpur, using Paediatric Refractive Error Profile (PREP) questionnaires.

METHODS

This is a cross sectional study. Myopic children who had been wearing ortho-K and SVSs for 12 months were recruited, and the questionnaires were distributed online. The PREP scores were obtained using a summary scoring method. The Shapiro-Wilk test was used to determine data normality. Unpaired t-test was performed for normally distributed data, and the Mann-Whitney test for non-normally distributed data. P < 0.05 was considered significant.

RESULTS

A total of 70 subjects participated in this study (45 ortho-K and 25 SVSs), with a mean age of 10.86 ± 0.73 years. The mean scores for all the items were higher in ortho-K than SVS wearers (p < 0.05). With regard to symptoms during ortho-K lens wear at night, <10 % of the subjects reported difficulty falling asleep, itch/burning/dry eyes and foreign body sensation after lens insertion.

CONCLUSION

Ortho-K improves the vision-related quality of life of myopic school children in Kuala Lumpur. Thus, it should be considered by more local optometrists when managing myopic children.

Morphological characteristics of the optic nerve head and impacts on longitudinal change in macular choroidal thickness during myopia progression

PURPOSE

The aim of this study was to investigate the association between morphological characteristics of Bruch's membrane opening distance (BMOD), border length (BL), border tissue angle (BTA), peripapillary atrophy (PPA) as well as axial length (AL) and incident decreased macular choroidal thickness (mChT) in young healthy myopic eyes.

METHODS

A total of 323 participants aged 17-30 years were included in the current 2-year longitudinal study. Each participant underwent detailed ocular examinations at baseline and follow-up. Data of AL, refraction error, PPA area, BMOD, BL, BTA and mChT were measured individually. Incident decreased mChT was defined as follow-up mChT of participants decreased into the lowest quartile of baseline mChT.

RESULTS

Subjects with longer AL, longer BMOD were more likely to have incident decreased mChT (odds ratio [OR], 1.56; 2.09, respectively, per 1 Z-score increment), whereas larger BTA was less likely to develop decreased mChT (odds ratio [OR], 0.51, per 1 Z-score increment). The area under the receiver operating curve (AUROC) of basic risk model for incident decreased mChT was 0.6284. After adding BMOD, BTA and AL separately to the basic risk model, the AUROC of the combination could reach 0.6967, 0.6944 and 0.7383, respectively. After combining BMOD, BTA and AL to the basic model, the AUROC of the combination showed the highest AUROC of 0.7608.

CONCLUSIONS

Bruch's membrane opening distance and AL are significant risk factors for incident decreased mChT, whereas BTA played protective role in the deterioration of mChT. In addition, a combination of BMOD, BTA and AL could serve as earlier predictors of the attenuation of mChT in myopia progression.

The prevalence of refractive errors in college students in Israel

PURPOSE

To determine the prevalence of refractive errors in Jewish and Arab college students in Israel and associations with ethnicity and sex.

METHODS

In this retrospective cross-sectional study, first-year college students underwent non-cycloplegic autorefraction and answered a questionnaire to assess age, sex, and self-identified ethnicity. Spherical equivalent refractive error (SER) was calculated, and the prevalence of hyperopia (>+0.50 Diopter, D), emmetropia (>-0.50 to +0.50 D), myopia (≤-0.50D, low ≤-0.50 to >-3.0D, moderate <-3.0 to >-6.0D, high ≤-6.0D), and astigmatism (>0.50D) were determined. Groups were compared using Chi-square or Fisher test. Univariate and multivariate analyses were conducted to identify factors associated with refractive errors.

RESULTS

Participants (n = 807) had a mean age of 22.1 ± 2.6 years (range: 17-30 years) and SER of -1.7 ± 2.2D (range: -13.3 to +5.7D). The prevalence and 95% confidence internal of myopia was 66.3% (63.0-69.6). Jewish students had a higher prevalence than Arab students for myopia (69.2% vs 60.3%), moderate (18.5% vs 12.2%) and high myopia (5.9% vs 1.9%) and astigmatism (51.4% vs 43.9%, p<0.05 for all), but not low myopia or hyperopia. Females had a higher prevalence of myopia than males (68.1% vs 58.7%, p<0.03). Jewish ethnicity was associated with myopia (OR=1.48, p = 0.01) and moderate myopia (OR=1.72, p = 0.01), and studying optometry was associated with moderate myopia (OR=1.63, p = 0.02). Sex and age were not associated with myopia.

CONCLUSION

Myopia prevalence in Israeli college students is high, showing associations with Jewish, but not Arab, ethnicity, suggesting that ethnic factors may play a role in the refractive differences between Arabs and Jews.

Ocular dimensions by three-dimensional magnetic resonance imaging in emmetropic versus myopic school children

Background

Magnetic resonance imaging (MRI) has been used to investigate eye shapes; however, reports involving children are scarce. This study aimed to determine ocular dimensions, and their correlations with refractive error, using three-dimensional MRI in emmetropic versus myopic children.

Methods

Healthy school children aged < 10 years were invited to take part in this cross-sectional study. Refraction and best-corrected distance visual acuity (BCDVA) were determined using cycloplegic refraction and a logarithm of the minimum angle of resolution (logMAR) chart, respectively. All children underwent MRI using a 3-Tesla whole-body scanner. Quantitative eyeball measurements included the longitudinal axial length (LAL), horizontal width (HW), and vertical height (VH) along the cardinal axes. Correlation analysis was used to determine the association between the level of refractive error and the eyeball dimensions.

Results

A total of 70 eyes from 70 children (35 male, 35 female) with a mean (standard deviation [SD]) age of 8.38 (0.49) years were included and analyzed. Mean (SD) refraction (spherical equivalent, SEQ) and BCDVA were -2.55 (1.45) D and -0.01 (0.06) logMAR, respectively. Ocular dimensions were greater in myopes than in emmetropes (all P < 0.05), with no significant differences according to sex. Mean (SD) ocular dimensions were LAL 24.07 (0.91) mm, HW 23.41 (0.82) mm, and VH 23.70 (0.88) mm for myopes, and LAL 22.69 (0.55) mm, HW 22.65 (0.63) mm, and VH 22.94 (0.69) mm for emmetropes. Significant correlations were noted between SEQ and ocular dimensions, with a greater change in LAL (0.46 mm/D, P < 0.001) than in VH (0.27 mm/D, P < 0.001) and HW (0.22 mm/D, P = 0.001).

Conclusions

Myopic eyeballs are larger than those with emmetropia. The eyeball elongates as myopia increases, with the greatest change in LAL, the least in HW, and an intermediate change in VH. These changes manifest in both sexes at a young age and low level of myopia. These data may serve as a reference for monitoring the development of refractive error in young Malaysian children of Chinese origin.

Myopia, its prevalence, current therapeutic strategy and recent developments: A Review

Myopia is a widespread and complex refractive error in which a person's ability to see distant objects clearly is impaired. Its prevalence rate is increasing worldwide, and as per WHO, it is projected to increase from 22% in 2000 to 52% by 2050. It is more prevalent in developed, industrial areas and affects individuals of all ages. There are a number of treatments available for the control of myopia, such as glasses, contact lenses, laser surgery, and pharmaceuticals agents. However, these treatments are less beneficial and have significant side effects. A novel molecule, 7-methylxanthine (7-MX), has been found to be a highly beneficial alternate in the treatment of myopia and excessive eye elongation. Many preclinical and clinical studies showed that 7-MX is effective for the treatment of myopia and is presently under phase II of clinical investigation. We have also investigated preclinical toxicity studies such as acute, sub-acute, sub-chronic, and chronic on rats. In these studies, 7-MX was found to be non-toxic as compared to other reported anti-myopic agents. Moreover, as an ideal drug, 7-MX is observed to have no or low toxicity, brain permeability, non-allergic, higher oral administration efficacy, and low treatment costs and thus qualifies for the long-term treatment of myopia. This review article on 7-MX as an alternative to myopia treatment will highlight recent findings from well-designed preclinical and clinical trials and propose a potential future therapy.

Distribution of refractive error among chinese primary school children in a rural area in Pahang, Malaysia

PURPOSE

This study aimed to determine the prevalence and status of refractive error among Chinese primary school children in a rural area in Pahang.

METHODS

This investigation entailed a cross-sectional retrospective study design involving case file analyses. The study site was a Chinese medium primary school in a rural locality within Bentong district. A total of 82 school children met the B40 classification and selection criteria; therefore, universal sampling was done. Analyses were done according to age group: Level 1 included ages 7 to 9 years, while Level 2 comprised 10- to 12-year-olds.

RESULTS

The mean age of the 82 Chinese school children was 9.72±1.5 years; the percentage of refractive errors found was 80.48%. A total of 53 (64.63%) children had myopia. Two-way ANOVA showed a significant difference (P=0.038) in the refractive error between age groups Level 1 and 2, but no significant difference (P=0.947) was observed in refractive error between genders. The chi-square test and Fishers exact test showed no significant association between the type of refractive error with gender (P>0.05) and age group (P=0.319).

CONCLUSION

Myopia was the most common type of refractive error among Chinese school children in a rural area in Pahang. Refractive error severity was influenced by age group but not by gender. Types of refractive error were not associated with age group and gender. Hence, it is recommended that Chinese school children in rural areas seek an annual vision screening or eye test.

Preliminary Evaluation of a Smartphone App for Refractive Error Measurement

Purpose

The purpose of this study was to evaluate the potential feasibility of using a smartphone app in myopia screening.

Methods

The app estimates myopic refractive error by measuring the far point distance for reading three 20/20 Tumbling E letters. In total, 113 myopic subjects with astigmatism no greater than -1.75 diopters (D) were enrolled from 5 sites. The mean age was 22 ± 8.5 years. The app measurement was compared with noncycloplegic subjective refraction measurement or autorefractor if subjective refraction was not available. In addition, 22 subjects were tested with the app for repeatability.

Results

For 201 eyes included, the range of spherical equivalent refraction error was 0 to -10.2 D. The app measurement and clinical measurement was highly correlated (Pearson R = 0.91, P < 0.001). There was a small bias (0.17 D) in the app measurement overall, and it was significantly different across the 5 sites due to different age of subjects enrolled at those sites (P = 0.001) - young adults in their 20s were underestimated the most by 0.49 D, whereas children were overestimated by 0.29 D. The mean absolute deviation of the app measurement was 0.65 D. The repeatability of multiple testing in terms of 95% limit of agreement was ±0.61 D.

Conclusions

Overall, the app measurement is consistent with clinical measurement performed by vision care professionals. The repeatability is comparable with that of some autorefractors. Age-associated human factors may influence the app measurement.

Translational Relevance

The app could be potentially used as a mass screening tool for myopia.

Significant increase in astigmatism in children after study at home during the COVID-19 lockdown

CLINICAL RELEVANCE

Evaluating changes in refractive astigmatism after 'study at home' during the COVID pandemic may shed light on the aetiology of refractive errors.

BACKGROUND

To investigate whether there has been a change in the proportion of astigmatism among primary school children after the school closure period during the COVID-19 pandemic.

METHODS

This observational study compared cross-sectional (2018: n = 112; 2020: n = 173) and longitudinal data (n = 38) collected from two vision screenings, one in 2018 and the other after the school closure period in 2020, in the same primary school for children aged 8-10 years. Non-cycloplegic refraction and axial length were measured using an open-field auto-refractometer and IOL Master, respectively. A questionnaire focusing on demographic information, near-work time, and outdoor activities was administered to parents of all participants.

RESULTS

While there were no significant differences in age, gender, or monthly family income between the two cohorts, astigmatism proportion (Cyl ≥ 0.75 D) in 2020 was 1.5-fold higher than that in 2018 (49.1% vs. 33.9%). The median cylindrical power was significantly higher in 2020 in older children (9 or 10 years old). More importantly, the children participating in both vision screenings had cylindrical power and J0 astigmatism significantly increased by 0.35 ± 0.40 D and 0.21 ± 0.25 D, respectively.

CONCLUSION

A significant increase in astigmatism (both proportion and magnitude) was found after the school closure period. Further studies are needed to investigate the origin of this increased astigmatism.

Design, methodology, and baseline of whole city-million scale children and adolescents myopia survey (CAMS) in Wenzhou, China

Background

Myopia is the most common visual impairment in children and adolescents worldwide. This study described an economical and effective population-based screening pipeline and performed the project of a million scale children and adolescents myopia survey (CAMS), which will shed light on the further study of myopia from the level of epidemiology and precision medicine.

Methods

We developed a novel population-based screening pattern, an intelligent screening process and internet-based information transmission and analysis system to carry out the survey consisting of school children in Wenzhou, China. The examination items include unaided distance visual acuity, presenting distance visual acuity, and non-cycloplegic autorefraction. Myopia and high myopia were defined as spherical equivalent (SE) ≤ − 1.00 diopters (D) and SE ≤ − 6.00 D, respectively. Next, the reports of the vision checking were automatically sent to parents and the related departments. The CAMS project will be done two to four times annually with the support of the government. An online eyesight status information management system (OESIMS) was developed to construct comprehensive and efficient electronic vision health records (EVHRs) for myopia information inquiry, risk pre-warning, and further study.

Results

The CAMS completed the first-round of screening within 30 days for 99.41% of Wenzhou students from districts and counties, in June 2019. A total of 1,060,925 participants were eligible for CAMS and 1,054,251 (99.37% participation rate) were selected through data quality control, which comprised 1305 schools, and 580,609, 251,050 and 170,967 elementary, middle, and high school students. The mean age of participants was 12.21 ± 3.32 years (6–20 years), the female-to-male ratio was 0.82. The prevalence of myopia in elementary, middle, and high school students was 38.16%, 77.52%, and 84.00%, respectively, and the high myopia incidence was 0.95%, 6.90%, and 12.98%.

Conclusions

The CAMS standardized myopia screening model involves automating large-scale information collection, data transmission, data analysis and early warning, thereby supporting myopia prevention and control. The entire survey reduced 90% of staff, cost, and time consumption compared with previous surveys. This will provide new insights for decision support for public health intervention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40662-021-00255-1.

Meridional Anisotropy of Foveal and Peripheral Resolution Acuity in Adults With Emmetropia, Myopia, and Astigmatism

Purpose

To quantify astigmatism-related meridional anisotropy in visual resolution at central, nasal, and inferior visual fields.

Methods

Three groups of young adults (range, 18–30 years) with corrected-to-normal visual acuity (logMAR 0) were recruited: (1) myopic astigmats (MA): spherical-equivalent error (SE) < −0.75D, with-the-rule astigmatism ≥ 2.00D, n = 19; (2) simple myopes (SM): SE < −0.75D, astigmatism ≤ 0.50D, n = 20; and (3) emmetropes (EM): SE ± 0.50D, astigmatism ≤ 0.50D, n = 14. Resolution acuity was measured for the horizontal and vertical gratings at central and peripheral visual fields (eccentricity: 15°) using a 3-down 1-up staircase paradigm. On- and off-axis refractive errors were corrected by ophthalmic lenses.

Results

The MA group exhibited meridional anisotropy preferring vertical gratings. At the central field, the MA group had better resolution acuity for vertical than horizontal gratings, and their resolution acuity for horizontal gratings was significantly worse than the SM and EM groups. At peripheral visual fields, both the SM and EM groups showed better resolution acuity for the radial (i.e., nasal field: horizontal gratings; inferior field: vertical gratings) than tangential orientation. However, the MA group tended to have better resolution acuity for the tangential orientation (i.e., vertical gratings), and their resolution acuity for horizontal gratings was significantly lower than the SM and EM groups at the nasal field. No significant differences were found in the inferior field among the three groups.

Conclusions

This study provided evidence of astigmatism-related meridional anisotropy at the fovea and nasal visual fields, underscoring the significant impact of astigmatism on orientation-dependent visual functions.

Prevalence of refractive errors among the school-going children in East Sikkim

Purpose:

Vision plays an important role in child's development for learning and communication. Uncorrected refractive error (URE) has become a major challenge to health care policy makers especially in school going children. We aim to report the prevalence of refractive error among the school students of the east district of Sikkim, India.

Methods:

A cross-sectional study was carried out among 15,954 school children under school health program of national program for control of blindness. The screening was conducted in 40 schools of east district which included primary, higher secondary, monastic and private schools.

Results:

The prevalence of refractive error was 6.7% among which myopia was the most common error present in 335 (31.1%) children, followed by astigmatism in 317 (29.4%) and the remaining 29 (2.6%) with hyperopia. The age group between 14-17 years had high prevalence of refractive error (9.2%). Females had slightly higher refractive error (6.93%) than males (5.9 %). Most backward classes were found to be highest suffering from refractive error (26.65%) and the least seen was found in schedule tribe (11.6%).

Conclusion:

The study provides a useful and baseline data about the refractive error amongst the school children of east Sikkim. A larger study needs to be conducted in all the schools of the state to get a clearer picture of RE and other eye related diseases to detect vision problem as early as possible.

Ocular biometric measurements and optical coherence tomography parameters in children with refractive errors and emmetropia

Purpose:

The aim of this study was to estimate and compare the differences in ocular biometric measurements (OBMs), central macular thickness (CMT), and retinal nerve fiber layer thickness (RNFLT) between children with refractive errors and those with emmetropia.

Methods:

A cross-sectional observational study of 205 children (334 eyes) aged between six and 18 years consisting of four groups (emmetropia, hypermetropia, myopia, and astigmatism) was carried out. Best-corrected visual acuity (BCVA), a detailed ocular examination, OBMs, spectral-domain optical coherence tomography (SD OCT) for RNFLT and CMT in both eyes were evaluated for each child.

Results:

Mean age of 205 children was 12.4 ± 3.2 years. 55.6% (n = 114) were girls and 44.4% (n = 91) were boys. There was a significant difference between the four groups for the parameters spherical equivalent (SE), keratometer readings K1and K2, axial length (AL), anterior chamber depth (ACD), vitreous chamber depth (VCD) and lens thickness (LT) (P < 0.0001). The mean central corneal thickness (CCT) was not significantly different between the four groups (P = 0.076). The mean RNFLT was thinner in the myopic group compared with the emmetropic group (P = 0.0048) There was no significant difference in the mean CMT across the four groups (P = 0.458).

Conclusion:

The data obtained are helpful in providing the normative as well as a comparative database on OBMs, RNFLT and CMT of the pediatric population. This also facilitates evaluation of RNFLT and CMT measurements in children with amblyopia, optic neuropathies, glaucoma, macular and retinal diseases.

Prevalence of Refractive Errors among Children in Saudi Arabia: A Systemic Review

Introduction:

The aim of this review was to estimate the prevalence of refractive errors (RE) and uncorrected refractive error (URE) in school-aged children of 4 to 14 years of age in Saudi Arabia.

Methods:

An extensive search was performed for peer-reviewed studies with data from the Saudi population during the past 20 years. The Cochrane Library, Pubmed, and Embase databases were used. Two independent reviewers evaluated publications and extracted the data. The quality of the studies was evaluated based on a critical appraisal tool designed for systematic reviews. The pooled prevalence of refractive error, uncorrected refractive error and different types of refractive error were estimated by using the random-effects meta-analysis.

Results and Discussion:

Eight school-based studies were included in this review. Among the overall pooled population of 12,247childern, the estimated prevalence of refractive error was 17.5% (95% CI: 11.1- 25). In the five studies that reported uncorrected refractive error (N=10,198), the pooled prevalence was 16.8% (95% CI: 11.4 – 21.3). The overall prevalence of refractive errors was very similar among boys, 16.8 (95% CI: 10.8- 24.1), and girls, 17.7% (95% CI: 10.2 – 25.9). Myopia was the most prevalent refractive error and was present in 40.8% (95% CI: 16.1 – 69.9) followed by astigmatism 29.7% (95% CI: 6.1- 61.7) and hyperopia 28.3% (95% CI: 16.9 – 41.2).

Conclusion:

This review highlights the high prevalence of refractive errors and uncorrected refractive error among children in Saudi Arabia. More studies are required using standardised methods in different regions where there is a lack of information on UREs. It is recommended that vision screening programs of children for RE should be implemented at the community level and integrated into school health programmes in order to detect UREs and prevent amblyopia, which is one of the debilitating consequences of URE.

Wearing Pattern and Awareness About Contact Lens Wear in Secondary School Students in Kuala Lumpur

PURPOSE

To investigate the wearing pattern and awareness about contact lens care among secondary school students in Kuala Lumpur.

PATIENTS AND METHODS

This is a cross-sectional study using self-administered validated questionnaires. A total of 2500 questionnaires were distributed to secondary school students (aged 13 to 18 years) from 5 selected schools in Kuala Lumpur. Descriptive statistics were used to analyze the results.

RESULTS

A total of 987 completed questionnaires were returned and analyzed. The response rate was 39.5%. Mean age of respondents was 15.5±2.5 years with 54.6% females. Around 9.9% of the respondents were contact lens wearers with female majority (78.6%) and the main reasons for wearing contact lenses were cosmesis (42.8%) and comfort (32.7%). Majority (92.2%) were soft contact lens wearers and daily wear (monthly disposable) is the preferred modality. Nevertheless, 42.4% purchased their lenses from unlicensed vendors and 18.4% rinsed their lenses using tap water. Regarding contact lens care, more than 50% of the respondents were not aware about the correct way of handling contact lenses.

CONCLUSION

Soft contact lens wear is popular among the secondary school students in Kuala Lumpur but the level of practice and knowledge about CL care are unsatisfactory. Thus, health communication strategies and aggressive public ocular health education that can influence behavior changes in teenagers are needed to overcome these issues.

IMI Risk Factors for Myopia

Risk factor analysis provides an important basis for developing interventions for any condition. In the case of myopia, evidence for a large number of risk factors has been presented, but they have not been systematically tested for confounding. To be useful for designing preventive interventions, risk factor analysis ideally needs to be carried through to demonstration of a causal connection, with a defined mechanism. Statistical analysis is often complicated by covariation of variables, and demonstration of a causal relationship between a factor and myopia using Mendelian randomization or in a randomized clinical trial should be aimed for. When strict analysis of this kind is applied, associations between various measures of educational pressure and myopia are consistently observed. However, associations between more nearwork and more myopia are generally weak and inconsistent, but have been supported by meta-analysis. Associations between time outdoors and less myopia are stronger and more consistently observed, including by meta-analysis. Measurement of nearwork and time outdoors has traditionally been performed with questionnaires, but is increasingly being pursued with wearable objective devices. A causal link between increased years of education and more myopia has been confirmed by Mendelian randomization, whereas the protective effect of increased time outdoors from the development of myopia has been confirmed in randomized clinical trials. Other proposed risk factors need to be tested to see if they modulate these variables. The evidence linking increased screen time to myopia is weak and inconsistent, although limitations on screen time are increasingly under consideration as interventions to control the epidemic of myopia.

Comparison of myopic progression in Finnish and Singaporean children

PURPOSE

To compare 3-year myopic progression between Finnish and Singaporean children.

METHODS

Myopic progression was compared between 9-year-old (mean age 9.7 ± 0.4 years, n = 92) and 11-year-old (mean age 11.7 ± 0.4 years, n = 144) Finnish (Finnish RCT) children and Singaporean children matched by age and refraction (SCORMMatched, n = 403) and 7- to 8-year-old Singaporean children matched only by refraction (SCORM Young, n = 186). Spherical equivalent (SE) was between -0.50 and -3.00 D. Refraction with cycloplegia was controlled annually for 3 years. Information on parental myopia, mother's education, time spent on near-work and outdoor time was gathered by parental questionnaire.

RESULTS

Three-year myopic progression was -2.08 ± 0.96 D and -1.30 ± 0.69 D in the Finnish RCT and Singaporean SCORM Matched 9-year-olds, respectively, and -1.34 ± 0.78 D, and -0.52 ± 0.44 D in the 11-year-olds, respectively (p < 0.001 between all groups). Myopic progression was fastest (-2.69 ± 0.89 D) in the SCORM 7-year-olds and similar between the SCORM Matched 9-year-olds and Finnish RCT 11-year-olds (p = 0.55). The Finnish RCT and SCORM Matched children showed significant differences in both daily near-work time (1.8 ± 1.0 versus 3.4 ± 1.9 hours per day, p < 0.001) and outdoor time (2.6 ± 0.9 versus 0.5 ± 0.4 hours per day, p < 0.001). These differences did not, however, explain the differences in myopic progression between the groups. More time spent outdoors was associated with less myopic progression in the Finnish RCT (r = 0.17, p = 0.009) group only. In the whole materials, greater myopic progression was associated with younger age at baseline (p < 0.001), younger age was associated with mother's higher education (p < 0.001), and mothers higher education was associated with myopia in both parents (p < 0.001).

CONCLUSION

Age at baseline was the most significant factor associated with myopic progression. However, at the same age and with the same initial refraction, the Finnish and Singaporean children showed different myopic progression. This result remains unexplained. Thus, age of myopia onset should be considered when comparing myopic progression between different samples and conducting treatment trials. Parental myopia may be a weak indicator of heredity of myopia.

Effect of Genetic-Environmental Interaction on Chinese Childhood Myopia

Objective

The purpose of this study was to evaluate the effect of genetic-environmental interaction on myopia in Chinese children aged 6 to 9 years.

Methods

Students had the physical examination and were required to provide basic demographic information. Their families were asked to fill in a questionnaire concerning factors related to myopia. Multiple regression analysis was performed, and adjusted risk ratio values were calculated to assess the role between gene and environment. Value of the environmental and genetic index (EGI) was calculated to demonstrate the effect of genetic-environmental interaction on myopia.

Results

The prevalence of myopia maintained at a high level. EGI was calculated as 0.125 suggesting that genetic factors may play the 12.5% role in the formation of myopia and environmental factors may play a role of 87.5% in the formation of myopia.

Conclusions

For young pupils aged 6 to 9 years, myopia prevalence maintained at a high level, and duration of homework time and staring at electronic screen were the strongest factors associated with myopia. The calculated value of EGI was low, which suggests that environmental factors may play the leading role in the formation of myopia. A long-term follow-up research to improve the accuracy value of EGI is our next job.

Sub-chronic and chronic toxicity evaluation of 7-methylxanthine: a new molecule for the treatment of myopia

Myopia (nearsightedness) is a vision disorder with a blurring of far objects, affect millions worldwide. 7-methylxanthine (7-MX) is a molecule that is presently under clinical investigation for the treatment of myopia. In the present study, we have investigated sub-chronic and chronic toxicity of 7-MX in comparison to other clinically used methylxanthines i.e., caffeine and theobromine as per OECD guidelines 408 and 452. 7-MX was administered orally for 90 days at three different doses of 250, 500, and 1000 mg/kg for sub-chronic toxicity evaluation, and at a limit dose of 1000 mg/kg in 180 days chronic toxicity evaluation in rats. In sub-chronic treatment, 7-MX showed no mortality and signs for toxicity in any group, whereas 10% and 40% mortality with signs for toxicity were observed in caffeine and theobromine treated groups, respectively. A similar, safety profile was observed with 7-MX in 180 days of chronic toxicity study. Further, to confirm any morphological changes in organs; ultrasound and X-rays analysis were performed and no changes in the size of organs, cyst formation, fluid retention, or crystal formation was observed. Thus, the repeated dose study of 7-MX for 180 days may augment the possibility of using 7-MX clinically for the safe and effective treatment of myopia.

Prevalence and risk factors of myopia in Han and Yugur older adults in Gansu, China: a cross-sectional study

Few studies have investigated the prevalence of myopia in Northwest China. This cross-sectional study aimed to investigate the prevalence and associated factors of myopia and high myopia in adults aged 40–80 years in the Han and Yugur populations living in Gansu Province, Northwest China. A total of 3,845 participants were included. The overall age- and sex-adjusted prevalence of myopia (spherical equivalent (SE) < −0.5 D), high myopia (SE < −6.0 D) and hyperopia (SE > + 0.5 D) were 16.4%, 0.7% and 26.2% in Yugur participants, respectively, and 34.3%, 5.0% and 19.2% in Han participants, respectively. The prevalence of myopia and high myopia in Han participants was significantly higher than that in Yugur participants (both P < 0.001). Yugur population, birth in rural areas, smoking history and outdoor work were found to be negatively associated with myopia. Higher education level and a family history of myopia were found to be positively associated with myopia in the study population. High myopia was negatively associated with Yugur population, aging, birth in rural areas and was positively associated with a family history of myopia. This study provided valuable information regarding the environmental risk factors of myopia and revealed an ethnic disparity in the prevalence of myopia in Gansu Province, Northwest China.

Prevalence of Myopia in Newly Enlisted Airmen at Joint Base San Antonio

Purpose

Myopia is the most common type of refractive error and can lead to significant visual impairment. The frequency of myopia has risen considerably, and its worldwide prevalence is expected to continue to increase. Myopia is present in an increasing number of Basic Military Trainees upon entry into the United States Air Force. This study aims to demonstrate the prevalence of myopia in newly enlisted members of the United States Air Force.

Methods

This study is an institutional retrospective analysis of data collected from the United States Air Force candidates entering Basic Military Training from 1 January 2017 to 31 March 2017. A random selection of 767 Air Force Basic Military Trainees were included in the analysis, yielding 1534 total eyes. The primary outcome measure studied is the mean spherical equivalent (MSE) of participants at initial evaluation. A linear regression analysis was performed to identify any associations related to participant demographics.

Results

Of participants analyzed, 45% had myopia (<−0.5 D) and 2% high myopia (<−6.0 D) upon entry into the United States Air Force. Myopia was found to be associated with male gender (p = <0.001).

Conclusion

Myopia is present in a significant proportion of Basic Military Trainees upon entry into the United States Air Force, regardless of age, gender, race, or ethnicity. The prevalence of myopia presented is higher than previous studies, reflecting a continued trend towards increased myopia prevalence worldwide.

Changes in axial length after orthokeratology lens treatment for myopia: a meta-analysis

PURPOSE

Orthokeratology (OK) lens is a popular optical method to control myopia progression. This study aimed to assess the effect of OK lens on axial length change compared with glasses.

METHODS

PubMed, Web of Science, and Embase were searched to retrieve the related articles. Then, the articles were selected according to predefined criteria. Standardized mean difference (SMD) and 95% confidence interval (CI) were selected as effect size for combining and analyzing the change in axial length.

RESULTS

A total of 13 articles were included in the present study. Different models were selected according to the heterogeneity of each analysis. The axial length change in OKs group was significantly smaller than control group; SMD (95% CI) of change in axial length was - 0.857 (- 1.146, - 0.568), p < 0.001 at the end of 1 year and - 0.701 (- 1.675, 0.272), p < 0.001 at the end of 2 years or longer time.

CONCLUSIONS

OK lens treatment appears more effective in slowing axial elongation than glasses during the early treatment of myopia in children.

The influence of age, refractive error, visual demand and lighting conditions on accommodative ability in Malay children and adults

PURPOSE

Near work, accommodative inaccuracy and ambient lighting conditions have all been implicated in the development of myopia. However, differences in accommodative responses with age and refractive error under different visual conditions remain unclear. This study explores differences in accommodative ability and refractive error with exposure to differing ambient illumination and visual demands in Malay schoolchildren and adults.

METHODS

Sixty young adults (21-25 years) and 60 schoolchildren (8-12 years) were recruited. Accommodative lag and accommodative fluctuations at far (6 m) and near (25 cm) were measured using the Grand Seiko WAM-5500 open-field autorefractor. The effects of mesopic room illumination on accommodation were also investigated.

RESULTS

Repeated-measures ANOVA indicated that accommodative lag at far and near differed significantly between schoolchildren and young adults [F(1.219, 35.354) = 11.857, p < 0.05]. Post hoc tests using the Bonferroni correction showed that at near, there was a greater lag in schoolchildren (0.486 ± 0.181 D) than young adults (0.259 ± 0.209 D, p < 0.05). Repeated-measures ANOVA also revealed that accommodative lag at near demands differed statistically between the non-myopic and myopic groups in young adults and schoolchildren [F(3.107, 31.431) = 12.187, p < 0.05]. Post hoc tests with Bonferroni correction showed that accommodative lag at near was significantly greater in myopic schoolchildren (0.655 ± 0.198 D) than in non-myopic schoolchildren (0.202 ± 0.141 D, p < 0.05) and myopic young adults (0.316 ± 0.172 D, p < 0.05), but no significant difference was found between myopic young adults (0.316 ± 0.172 D) and non-myopic young adults (0.242 ± 0.126 D, p > 0.05). Accommodative lag and fluctuations were greater under mesopic room conditions for all ages [all p < 0.05].

CONCLUSION

Greater accommodative lag was found in myopes than in emmetropes, in schoolchildren than in adults, and under mesopic conditions than under photopic conditions. Accommodative fluctuations were greatest in myopes and in mesopic conditions. These results suggest that differences exist in the amount of blur experienced by myopes and non-myopes at different ages and under different lighting conditions.

Non-Orthogonal Refractive Lenses for Non-Orthogonal Astigmatic Eyes

Purpose: To present a novel design method for non-orthogonal lenses to reduce the problem of residual astigmatism in non-orthogonal, astigmatic eyes Methods: A method to create spectacle trial lenses with non-orthogonal power axes was developed based on a novel optimised light ray-tracing algorithm rather than conventional lens design methods which could not fully eliminate spherical aberration. Using this method, three sets of refraction trial lenses were made with the angles between power axes of each set controlled at 80°, 70° and 60°, respectively. Within each set, the cylindrical power varied from -1.00 D to -6.00 D in 1.00 D steps in addition to a -0.50 D lens. Computer-based numerical simulation of the lenses optical performance was carried out to apply orthogonal and non-orthogonal lenses on simulated astigmatic eyes. Subsequently, three clinical trial cases were investigated. Results: Computer-simulated optical performance of non-orthogonal lenses showed the ability to achieve high performance in correcting non-orthogonal astigmatism. Subsequently, three patients with irregular astigmatism were refracted with the non-orthogonal lens sets, and clinically observed improvement at least two lines in the LogMAR chart was achieved in all three cases, compared with correction with orthogonal lenses, along with subjective improvement in image quality. Conclusions: Non-orthogonal astigmatism, which is commonly ignored by current eye prescription systems, is taken into account in this study in the design of spectacle and soft contact lenses. The new approach considers the possible non-orthogonal positions of the eye's two optical power meridians and appears to be better able to correct the vision of irregular astigmatic eyes and significantly reduce residual astigmatism.

Prevalence and Risk Factors of Amblyopia among Refractive Errors in an Eastern European Population

Background and objective: Amblyopia is the leading cause of visual impairment in children and adults and is very common during childhood. The aim of this study was to identify the prevalence and the risk factors of amblyopia in a pediatric population with refractive errors from an Eastern European country. Materials and methods: A total of 1231 children aged 5–16 years, who had refractive errors and were examined from January to August 2017, were enrolled in a cross-sectional population-based study. Every child underwent a complete ophthalmological exam. Amblyopia was defined as a visual acuity (VA) of less than 0.63. The study respected the Multi-Ethnic Pediatric Eye Disease Study (MEPEDS) criteria for defining amblyopia (MEPEDS, 2008). Parents participated in a face-to-face interview. The questionnaire contained details about their family history of amblyopia; the child’s maternal nutritional status in the preconception period; their history of maternal smoking or work in a toxic environment; the child’s birth, and the child’s history of congenital naso-lacrimal duct obstruction (CNLDO). Results: Amblyopia was identified in 2.8% of the participants. The ocular conditions hyperopia (p = 0.0079), astigmatism (p = 0.046), anisometropia (p < 0.001), esotropia (p < 0.001), exotropia (p = 0.0195), and CNLDO (p < 0.001), as well as a family history of amblyopia (p < 0.001), were associated with amblyopia. The non-ocular risk factors for amblyopia that were found in the study included low birth weight (p < 0.0009), prematurity (p < 0.001), an Apgar score under 7 (p = 0.0008), maternal age, maternal smoking history or work in toxic environment (p < 0.001), and maternal body mass index in the preconception period (p < 0.003). Conclusions: Some of the risk factors we identified for amblyopia are modifiable factors. This is an important observation as an adequate health education program can provide the relevant information for future mothers that will allow for a better management of the condition. We also wanted to highlight the need for amblyopia screening starting from the age of 3 years in case of significant parental refractive errors, strabismus, prematurity, and maternal risk factors.

Longitudinal Changes of Optic Nerve Head and Peripapillary Structure during Childhood Myopia Progression on OCT: Boramae Myopia Cohort Study Report 1

PURPOSE

To delineate longitudinal changes in the optic nerve head (ONH) and peripapillary structure during myopia progression in childhood using spectral-domain (SD) OCT and to explore the factors associated with myopic ONH and peripapillary changes.

DESIGN

Prospective cohort study.

PARTICIPANTS

Twenty-three healthy children with myopia (46 eyes).

METHODS

The participants underwent fundus photography, SD OCT, and axial length (AXL) measurements every 6 months for 2 years. Based on the morphologic changes of the ONH and β-zone parapapillary atrophy (PPA), eyes were classified as group A (ONH unchanged without β-zone PPA; 11 eyes), group B (ONH changed without β-zone PPA at baseline; 10 eyes), group C (ONH changed with β-zone PPA at baseline; 15 eyes), and group D (ONH unchanged with β-zone PPA; 10 eyes). The configuration of the border tissue (BT) at the temporal margin of the ONH was assessed, and the ONH parameters, including Bruch's membrane opening distance (BMOD), border length (BL), and BT angle (BTA), were measured on horizontal SD OCT scans.

MAIN OUTCOME MEASURES

Changes in ONH parameters and associated factors.

RESULTS

Group B showed the greatest AXL increase per year (group B > group C > group A = group D; P < 0.001). During the follow-up periods, the BT configuration initially was changed from internally oblique to externally oblique (group B) and was stretched, resulting in optic disc ovality and γ-zone PPA development (group C). In group C, BL was increased significantly nasally and BTA was decreased significantly, whereas BMOD remained stable (P < 0.001, P < 0.001, and P = 0.100, respectively). In the multivariate analysis using the generalized linear mixed-effect model, the changes of BL and BTA were associated with axial elongation (P = 0.028 and P = 0.010, respectively).

CONCLUSIONS

Development of myopic optic disc and γ-zone PPA during myopia progression was delineated using SD OCT images. During the ONH and peripapillary changes, the BL was increased nasally and the BTA was decreased, whereas the BMOD remained relatively stable. The association of axial elongation with ONH and peripapillary tissue changes may facilitate understanding of the relationship between myopia and glaucoma.

Non-Orthogonal Corneal Astigmatism among Normal and Keratoconic Brazilian and Chinese populations

PURPOSE

To investigate the prevalence of non-orthogonal astigmatism among normal and keratoconic Brazilian and Chinese populations.

METHODS

Topography data were obtained using the Pentacam High Resolution (HR) system ^® from 458 Brazilian (aged 35.6 ± 15.8 years) and 505 Chinese (aged 31.6 ± 10.8 years) eyes with no history of keratoconus or refractive surgery, and 314 Brazilian (aged 24.2 ± 5.7 years) and 74 Chinese (aged 22.0 ± 5.5 years) keratoconic eyes. Orthogonal values of optical flat and steep powers were determined by finding the angular positions of two perpendicular meridians that gave the maximum difference in power. Additionally, the angular positions of the meridians with the minimum and maximum optical powers were located while being unrestricted by the usual orthogonality assumption. Eyes were determined to have non-orthogonal astigmatism if the angle between the two meridians with maximum and minimum optical power deviated by more than 5° from 90°.

RESULTS

Evidence of non-orthogonal astigmatism was found in 39% of the Brazilian keratoconic eyes, 26% of the Chinese keratoconic eyes, 29% of the Brazilian normal eyes and 20% of the Chinese normal eyes.

CONCLUSIONS

The large percentage of participants with non-orthogonal astigmatism in both normal and keratoconic eyes illustrates the need for the common orthogonality assumption to be reviewed when correcting for astigmatism. The prevalence of non-orthogonality should be considered by expanding the prescription system to consider the two power meridians and their independent positions.

Prevalence and Related Factors for Myopia in School-Aged Children in Qingdao

Purpose

To investigate the prevalence and related factors for myopia in school-aged children in the Economic and Technological Development Zone of Qingdao, Eastern China.

Methods

A total of 4890 (aged 10 to 15 years) students were initially enrolled in this study. 3753 (76.75%) students with completed refractive error and questionnaire data were analyzed. The children underwent a comprehensive eye examination. Multiple logistic regression models were applied to assess possible factors associated with myopia.

Results

The prevalence of myopia increased as the children's grade increased (χ² = 560.584, P < 0.001). Low myopia was the main form of myopia in adolescent students (30.22%). With the growth of age, students spent significantly more time on near work (P = 0.03) and less time on outdoor activity (P < 0.001). In multivariate models, only the following variables were significantly associated with myopia: age, two myopic parents, outdoor activity time, and continuous near work without 5 min rest.

Conclusions

The prevalence of myopia increased as the grade increased. Age, two myopic parents, and continuous near work time without 5 min rest were risk factors for myopia. Outdoor activities had protective effect for myopia.

Quantification of Macular Vascular Density Using Optical Coherence Tomography Angiography and Its Relationship with Retinal Thickness in Myopic Eyes of Young Adults

Purpose

To quantify macular vascular density using optical coherence tomography angiography (OCTA) and to investigate its relationship with retinal thickness in myopic eyes of young adults.

Methods

In this cross-sectional study, 268 myopic eyes without pathological changes were recruited and divided into three groups: mild myopia (n = 81), moderate myopia (n = 117), and high myopia (n = 70). Macular vascular density was quantified by OCTA and compared among three groups. Average retinal thickness, central subfield thickness, and macular ganglion cell complex (mGCC) thickness were also evaluated and compared. Correlations among these variables were analyzed.

Results

There was no statistical difference in superficial (62.3 ± 5.7% versus 62.7 ± 5.9% versus 63.8 ± 5.5%) and deep macular vascular densities (58.3 ± 9.6% versus 59.2 ± 9.3% versus 60.9 ± 7.9%) among mild-myopia, moderate-myopia, and high-myopia groups (both P > 0.05). Superficial and deep macular vascular densities both had correlations with mean arterial pressure. Furthermore, superficial macular vascular density was significantly correlated with mGCC thickness.

Conclusions

Varying degrees of myopia did not affect macular vascular density in young healthy adults. In addition, superficial macular vascular density, as an independent factor, was positively correlated with mGCC thickness.

Refractive error in Chinese with type 2 diabetes and its association with glycaemic control

BACKGROUND

The aim of this study was to determine the prevalence of refractive errors and their association with glycaemic control among adults with type 2 diabetes mellitus (T2DM) in eastern China.

METHODS

A community-based survey, including 913 adults with T2DM aged 30 to 89 years, was conducted. Refractive error was assessed by autorefraction, after which subjective refraction was performed. Ocular biometric parameters were measured by non-contact partial coherence laser interferometry. Myopia was defined as spherical equivalent (SE) less than -0.50 dioptres (D), high myopia as SE less than -5.00 D, hyperopia as SE greater than 0.50 D and astigmatism as cylinder less than -0.50 D.

RESULTS

After excluding participants who had undergone cataract surgery, 839 were included in the data analyses and 96.1 per cent were found to have refractive errors. The overall prevalences of myopia, high myopia, hyperopia and astigmatism were 28.2 per cent (95 per cent confidence interval [CI] 25.2-31.3), 6.3 per cent (95 per cent CI 4.7-8.0), 46.4 per cent (95 per cent CI 43.0-49.7) and 81.0 per cent (95 per cent CI 78.4-83.7) with no gender differences observed (all p > 0.10). In multivariate analysis, myopia was associated with decreasing age (odds ratio [OR] = 0.86, p = 0.01; per year increase), higher blood levels of haemoglobin A_1c (HbA_1c ) (OR = 1.12, p = 0.05; per unit increase), higher education levels (OR = 5.10, p < 0.001; university or college versus illiterate or primary school) and the presence of nuclear cataract (OR = 2.36, p < 0.001).

CONCLUSIONS

Refractive errors may be associated with glycaemic control among T2DM patients. Longitudinal analyses are warranted to examine the relationship between changes in HbA_1c and the development of refractive errors.

The epidemics of myopia: Aetiology and prevention

There is an epidemic of myopia in East and Southeast Asia, with the prevalence of myopia in young adults around 80-90%, and an accompanying high prevalence of high myopia in young adults (10-20%). This may foreshadow an increase in low vision and blindness due to pathological myopia. These two epidemics are linked, since the increasingly early onset of myopia, combined with high progression rates, naturally generates an epidemic of high myopia, with high prevalences of "acquired" high myopia appearing around the age of 11-13. The major risk factors identified are intensive education, and limited time outdoors. The localization of the epidemic appears to be due to the high educational pressures and limited time outdoors in the region, rather than to genetically elevated sensitivity to these factors. Causality has been demonstrated in the case of time outdoors through randomized clinical trials in which increased time outdoors in schools has prevented the onset of myopia. In the case of educational pressures, evidence of causality comes from the high prevalence of myopia and high myopia in Jewish boys attending Orthodox schools in Israel compared to their sisters attending religious schools, and boys and girls attending secular schools. Combining increased time outdoors in schools, to slow the onset of myopia, with clinical methods for slowing myopic progression, should lead to the control of this epidemic, which would otherwise pose a major health challenge. Reforms to the organization of school systems to reduce intense early competition for accelerated learning pathways may also be important.

Longitudinal Changes in Refractive Error in a Pediatric Referral Population in Korea

PURPOSE

To investigate changes in the spherical equivalent (SE) refractive error and astigmatism in a pediatric referral population in Korea with longitudinal follow-up and to evaluate the effect of risk factors on changes in refractive error.

METHODS

This was a retrospective case series. In total, 221 patients who presented to a tertiary care hospital when aged 3 to 9 years and who underwent at least 10 years of follow-up were enrolled. The patients were divided into groups in terms of the initial extent of SE refractive error, the initial extent of astigmatism, sex, and ocular alignment. Changes in SE and astigmatism were compared among the groups.

RESULTS

The patients were followed up for a mean of 11.19 ± 1.81 years. An overall negative shift in SE refractive error and increasing tendency in astigmatism during the follow-up period were noted. The negative shift in SE refractive error in the myopia group was significantly greater than those in the emmetropia and hyperopia groups. The change in astigmatism in the myopia group was significantly greater than that in the hyperopia group. The change in astigmatism in the low astigmatism group was significantly greater than those in the moderate and high astigmatism groups. Sex did not influence the changes in SE refractive error or astigmatism.

CONCLUSIONS

A pediatric referral population in Korea showed a negative shift in SE refractive error and increasing tendency in astigmatism during childhood. Changes in refractive error may be influenced by the initial degree of SE refractive error and astigmatism. [J Pediatr Ophthalmol Strabismus. 2017;54(1):43-51.].

Prevalence and degrees of myopia and hyperopia at Gondar University Hospital Tertiary Eye Care and Training Center, Northwest Ethiopia

BACKGROUND

Refractive errors are the second and third leading cause of visual impairment and blindness in Ethiopia, respectively. The situation is worse where accessing spectacles, which are the only management option in developing countries, is a major issue. Gondar University Hospital Tertiary Eye Care and Training Center is the only referral eye care center, and it lacks published evidence on the prevalence and degrees of refractive errors (myopia and hyperopia).

OBJECTIVE

The purpose of this study was to determine the prevalence and degrees of myopia and hyperopia at Gondar University Tertiary Eye Care and Training Center.

MATERIALS AND METHODS

Records of 1,921 patients presented to refraction service at Gondar University Hospital Tertiary Eye Care and Training Center from January 2010 to January 2014 were reviewed. All cases of refractive errors (with visual improvement of at least one line) were converted into spherical equivalents (SE = sphere + ½ cylinder). Myopia was defined as SE ≤ -0.25 D and hyperopia ≥ +0.25 D.

RESULTS

The study comprised of 61.1% males and 38.9% females; the patients had an average age of 40±17 years. The overall prevalence of refractive errors (myopia and hyperopia) was 76.3% (95% confidence interval: 75%-77%). Myopia was present in 34.5% patients and hyperopia in 38.3%. Low-degree hyperopia (86%) and low-degree myopia (49.5%) were the most frequent refractive errors.

CONCLUSION

Myopia and hyperopia are major reasons for patients to visit Gondar University Hospital Tertiary Eye Care and Training Center. Low-degree myopia and hyperopia were the most common refractive errors. Stocking appropriate power lenses is needed at this tertiary eye care center in order to alleviate this problem in Ethiopia.

Is myopia another clinical manifestation of insulin resistance?

Myopia is a multifactorial visual refraction disease, in which the light rays from distant objects are focused in front of retina, causing blurry vision. Myopic eyes are characterized by an increased corneal curvature and/or ocular axial length. The prevalence of myopia has increased in recent decades, a trend that cannot be attributed exclusively to genetic factors. Low and middle income countries have a higher burden of refractive error, which we propose could be a consequence of a shorter exposure time to a westernized lifestyle, a phenomenon that may also explain the rapid increase in cardiometabolic diseases, such as diabetes, among those populations. We suggest that interactions between genetic, epigenetic and a rapidly changing environment are also involved in myopia onset and progression. Furthermore, we discuss several possible mechanisms by which insulin resistance may promote abnormal ocular growth and myopia to support the hypothesis that insulin resistance and hyperinsulinemia are involved in its pathogenesis, providing a link between trends in myopia and those of cardiometabolic diseases. There is evidence that insulin have direct ocular growth promoting effects as well an indirect effect via the induction of insulin-like growth factors leading to decreases insulin-like growth factor-binding protein, also implicated in ocular growth.

Five-Year Progression of Refractive Errors and Incidence of Myopia in School-Aged Children in Western China

BACKGROUND

To determine the change in refractive error and the incidence of myopia among school-aged children in the Yongchuan District of Chongqing City, Western China.

METHODS

A population-based cross-sectional survey was initially conducted in 2006 among 3070 children aged 6 to 15 years. A longitudinal follow-up study was then conducted 5 years later between November 2011 and March 2012. Refractive error was measured under cycloplegia with autorefraction. Age, sex, and baseline refractive error were evaluated as risk factors for progression of refractive error and incidence of myopia.

RESULTS

Longitudinal data were available for 1858 children (60.5%). The cumulative mean change in refractive error was -2.21 (standard deviation [SD], 1.87) diopters (D) for the entire study population, with an annual progression of refraction in a myopic direction of -0.43 D. Myopic progression of refractive error was associated with younger age, female sex, and higher myopic or hyperopic refractive error at baseline. The cumulative incidence of myopia, defined as a spherical equivalent refractive error of -0.50 D or more, among initial emmetropes and hyperopes was 54.9% (95% confidence interval [CI], 45.2%-63.5%), with an annual incidence of 10.6% (95% CI, 8.7%-13.1%). Myopia was found more likely to happen in female and older children.

CONCLUSIONS

In Western China, both myopic progression and incidence of myopia were higher than those of children from most other locations in China and from the European Caucasian population. Compared with a previous study in China, there was a relative increase in annual myopia progression and annual myopia incidence, a finding which is consistent with the increasing trend on prevalence of myopia in China.

Global variations and time trends in the prevalence of childhood myopia, a systematic review and quantitative meta-analysis: implications for aetiology and early prevention

The aim of this review was to quantify the global variation in childhood myopia prevalence over time taking account of demographic and study design factors. A systematic review identified population-based surveys with estimates of childhood myopia prevalence published by February 2015. Multilevel binomial logistic regression of log odds of myopia was used to examine the association with age, gender, urban versus rural setting and survey year, among populations of different ethnic origins, adjusting for study design factors. 143 published articles (42 countries, 374 349 subjects aged 1–18 years, 74 847 myopia cases) were included. Increase in myopia prevalence with age varied by ethnicity. East Asians showed the highest prevalence, reaching 69% (95% credible intervals (CrI) 61% to 77%) at 15 years of age (86% among Singaporean-Chinese). Blacks in Africa had the lowest prevalence; 5.5% at 15 years (95% CrI 3% to 9%). Time trends in myopia prevalence over the last decade were small in whites, increased by 23% in East Asians, with a weaker increase among South Asians. Children from urban environments have 2.6 times the odds of myopia compared with those from rural environments. In whites and East Asians sex differences emerge at about 9 years of age; by late adolescence girls are twice as likely as boys to be myopic. Marked ethnic differences in age-specific prevalence of myopia exist. Rapid increases in myopia prevalence over time, particularly in East Asians, combined with a universally higher risk of myopia in urban settings, suggest that environmental factors play an important role in myopia development, which may offer scope for prevention.

Near work-induced transient myopia in Indian subjects

PURPOSE

The aim was to determine the characteristics of near work-induced transient myopia (NITM) in asymptomatic Indian subjects and the influence of target size and contrast.

METHODS

Two studies were conducted: First, 24 myopes and 24 emmetropes viewed four targets (N8 and N12 with 50 and 90 per cent contrasts) placed at 0.2 m for five minutes. The refractive status was assessed objectively, before and after carrying out the near task, with the Grand Seiko WAM-5500 open-field autorefractor under monocular viewing conditions. Second, a different group of 24 myopes and 24 emmetropes viewed a N12 target with 90 per cent contrast for 60 minutes with pre- and post-refractive state measurements repeated as above. NITM was defined as the difference between pre-task and post-task distance refraction.

RESULTS

In the first study, myopes demonstrated an initial post-task myopic shift of 0.21 D, whereas emmetropes demonstrated a small hyperopic shift of 0.07 D (p < 0.001). The myopes demonstrated a decay time constant of 6.07 seconds. There was no effect of target size or contrast on the magnitude of the NITM or the decay time constant (p > 0.05). In the second study, myopes showed a NITM of 0.31 D, which was significantly greater than emmetropes (p < 0.001). The myopes demonstrated a decay time constant of 8.16 seconds.

CONCLUSION

The magnitude of the NITM was higher in myopes compared to emmetropes for both five minute and 60 minute viewing time. The NITM decayed slightly faster than that found in previous literature for some other ethnic groups. Potential reasons for these findings are discussed.

Refractive status of Chinese with laser-treated retinopathy of prematurity

Purpose

To analyze changes in myopia, astigmatism, and anisometropia after laser treatment of retinopathy of prematurity (ROP), including aggressive posterior retinopathy of prematurity (APROP), in Mainland Chinese children.

Methods

This was a retrospective study of children who had laser treatment for threshold or type 1 prethreshold ROP between January 2004 and October 2012 and age-matched control subjects with spontaneously regressed type 2 prethreshold ROP. One hundred fifteen eyes of 60 patients were included as the laser-treated group, which were further subdivided into APROP and non-APROP groups. Thirty-seven eyes of 20 patients who were diagnosed during the same period were included as the control group. Between 12 and 36 months postnatal age (PA) (mean [±SD], 22.9 [±8.1] months), cycloplegic retinoscopy was performed to measure refractive outcomes. A general linear model was used to analyze refractive changes among different groups at each PA.

Results

After adjusting for PA and the correlation between right and left eyes, the magnitude and proportion of astigmatism (p = 0.04 and p = 0.004, respectively) and myopia (p < 0.0001 and p = 0.006, respectively) were greater in the laser-treated group than in the control group. The differences in myopia were even greater in children with APROP than those with non-APROP, whereas the differences in astigmatism were not. Eyes with APROP had higher prevalence of high myopia and spherical anisometropia than the control (p = 0.002 and p = 0.02, respectively) and the non-APROP groups (p < 0.0001 and p = 0.04, respectively).

Conclusions

Children with laser treatment for ROP, including APROP, tended to have higher myopia, astigmatism, and anisometropia, which may progress to amblyopia. These findings highlight the need for regular refractive screening after laser treatment of ROP.

Moderate hyperopia prevalence and associated factors among elementary school students

Hyperopia is the most common refractive condition in childhood. There are few studies on moderate hyperopia and associated factors. This study aims to investigate the prevalence of moderate hyperopia and associated factors among school children. A cross-sectional study comprising 1,032 students attending 1st to 8th grades at two public schools was conducted in a Southern Brazilian urban area in 2012. Cycloplegia was used to examine both eyes and refractive error was measured through auto-refraction. A socioeconomic and cultural questionnaire was administered. Multivariable analysis was performed through Poisson regression. Moderate hyperopia prevalence was 13.4% (95% CI, 11.2-15.4) and 85% of these did not wear glasses. Age was inversely associated with moderate hyperopia, while female gender RP = 1.39 (95%CI, 1.02 - 1.90) and white skin RP = 1.66 (95%CI, 1.04 - 2.66) were risk factors for this outcome. This study makes progress in estimating mild and moderate hyperopia prevalence both by age range and specific age. It emphasizes how the lack of this condition being corrected in southern Brazil is a serious problem. It highlights the importance of detailing and characterizing the amount of time spent on close-range, long-range and outdoor activities.

Childhood myopia: epidemiology, risk factors, and prevention

Our understanding of the dynamic interaction between the eye's growth and its ability to adapt to maintain vision has shown that childhood myopia is a significant prediction of progressive myopia and the potentially severe ocular comorbidities associated with it. It is important for us to better understand this process and its risk factors in order to better develop a prevention and treatment strategy. This article will discuss the epidemiology, risk factors and current therapeutic regimens for reducing myopic progression.