Sensitivity and specificity of visual acuity screening for refractive errors in school children

Cutoff values of axial length/corneal radius ratio for determining myopia vary with age among 3-18 years old children and adolescents

PURPOSE

To investigate the effectiveness and cutoffs of axial length/corneal radius (AL/CR) ratio for myopia detection in children by age.

METHODS

Totally, 21 kindergartens and schools were enrolled. Non-cycloplegic autorefraction (NCAR), axial length (AL), horizontal and vertical meridian of corneal radius (CR1, CR2), and cycloplegic autorefraction were measured. Receiver operating characteristic (ROC) curve was used to obtain the effectiveness and cutoff for myopia detection.

RESULTS

Finally, 7803 participants aged 3-18 years with mean AL/CR ratio of 2.99 ± 0.16 were included. Area under the ROC curve (AUC) of AL/CR ratio for myopia detection (0.958 for AL/CR1, 0.956 for AL/CR2, 0.961 for AL/CR) was significantly larger than that of AL (0.919, all P < 0.001), while AUCs of the three were similar with different cutoffs (> 2.98, > 3.05, and > 3.02). When divided by age, the ROC curves of AL/CR ratio in 3- to 5-year-olds showed no significance or low accuracy (AUCs ≤ 0.823) in both genders. In ≥ 6-year-olds, the accuracies were promising (AUCs ≥ 0.883, all P < 0.001), the cutoffs basically increased with age (from > 2.93 in 6-year-olds to > 3.07 in 18-year-olds among girls, and from > 2.96 in 6-year-olds to > 3.07 in 18-year-olds among boys). In addition, boys presented slightly larger cutoffs than girls in all ages except for 16 and 18 years old. For children aged 3-5 years, AL/CR ratio or AL combined with NCAR increased AUC to > 0.900.

CONCLUSION

AL/CR ratio provided the best prediction of myopia with age-dependent cutoff values for all but preschool children, and the cutoffs of boys were slightly larger than those of girls. For preschool children, AL/CR ratio or AL combined with NCAR is recommended to achieve satisfactory accuracy. AL/CR ratio calculated by two meridians showed similar predictive power but with different cutoffs.

Urban greenspace and visual acuity in schoolchildren: a large prospective cohort study in China

BACKGROUND

Greenspace is known to have a positive impact on human health and well-being, but its potential effects on visual acuity have not been extensively studied.

OBJECTIVES

Our aim was to examine the relationship between long-term greenspace exposure and visual acuity in children, while also exploring the potential mechanisms in this association.

METHODS

We conducted this prospective cohort study based on the Children's growth environment, lifestyle, physical, and mental health development project (COHERENCE), which screened 286,801 schoolchildren in Guangzhou, China, starting in the 2016/17 academic year and followed them up for three academic years (2017/18-2019/20). Visual acuity was measured using a standardized logarithmic chart, and visual impairment was defined as visual acuity worse than 0.0 logarithm of the minimum angle of resolution (LogMAR) units in the better eye. We used the Normalized Difference Vegetation Index (NDVI), the Soil-Adjusted Vegetation Index (SAVI), and the Enhanced Vegetation Index (EVI) to assess the greenspace surrounding child's geocoded home and school at each visit.

RESULTS

Our analysis indicated that higher greenspace exposure was associated with greater visual acuity z-score at baseline and with slower decline in visual acuity z-score during the 3-year follow-up. An interquartile range increase in home-school-based NDVI 300m was associated with a 7% decrease [hazard ratios (HRs): 0.93, 95% confidence interval (CI): 0.92, 0.94] in the risk of visual impairment. We also found that air pollution, physical activity, outdoor time, and recreational screen time partially mediated the greenspace-visual acuity association.

CONCLUSION

Our findings suggest that increasing greenspace exposure could benefit children's visual acuity development and reduce the risk of visual impairment by reducing air pollution and recreational screen time while increasing physical activity and outdoor time. All results could have potential policy implications, given the individual and societal burdens associated with visual impairment.

Validity and Reliability of Vis-Screen Application: A Smartphone-Based Distance Vision Testing for Visual Impairment and Blindness Vision Screening

Background and Objectives: The health-related mobile applications (app) might assist in promoting inclusive health and tele-treatment, especially for the less severe diseases. In this paper, a study had been done to determine the app's reliability in terms of raters and the app's agreement with the Snellen chart. Materials and Methods: A cross-sectional sectional study was conducted between November 2019 and September 2020. Participants were selected via purposive sampling from selected communities in Terengganu state. All participants underwent vision testing with the Vis-Screen app and Snellen chart for validity and reliability accordingly. Results: A total of 408 participants were involved, with a mean age of 29.3. The sensitivity of the presenting vision of the right eye (PVR) ranged from 55.6% to 88.4%, with specificity between 94.7% to 99.3%, while the positive and negative predictive values were between 57.9% and 81.7% and 96.8% and 99.0%, respectively. The positive likelihood ratios ranged between 16.73 and 73.89, whereas the negative likelihood ratios ranged from 0.12 to 0.45. The area under the receiver operating characteristic curve (AUC) for all cut-off points ranged between 0.93 and 0.97, and the optimum cut-off point was at 6/12. The kappa values for intra-rater and inter-rater were 0.85 and 0.75, respectively, while the app's reliability with the Snellen chart was 0.61. Conclusions: Vis-Screen was concluded to be valid and reliable for use as a screening tool for detecting individuals with visual impairment and blindness in the community. A valid and reliable portable vision screener like Vis-Screen will help expand the eye care feasibility while providing similar accuracy as the conventional charts in clinical practices.

Prevalence of visual impairment due to refractive error among children and adolescents in Ethiopia: A systematic review and meta-analysis

Introduction

Globally, the prevalence of refractive error was 12%, and visual impairment due to refractive error was 2.1%. In sub-Saharan Africa, the prevalence of refractive error and visual impairment due to refractive error was 12.6% and 3.4%, respectively. In Ethiopia, the prevalence of visual impairment due to refractive error varies from 2.5% in the Gurage zone to 12.3% in Hawassa city. Hence, this Meta-analysis aimed to summarize the pooled prevalence of visual impairment due to refractive error in Ethiopia.

Methods

A systematic search of the literature was conducted by the authors to identify all relevant primary studies. All articles on the prevalence of visual impairment due to refractive error in Ethiopia were identified through a literature search. The databases used to search for studies were PubMed, Science Direct, POPLINE, HENARI, Google Scholar, and grey literature was searched on Google until December 15, 2021. In this meta-analysis, the presence of publication bias was evaluated using funnel plots and Begg’s tests at a significance level of less than 0.05. The sensitivity analysis was conducted to check for a single study’s effect on the overall prevalence of refractive error.

Result

About 1664 studies were retrieved from initial electronic searches using international databases and google searches. A total number of 20,088 children and adolescents were included in this meta-analysis. The pooled prevalence of visual impairment due to refractive error in Ethiopia using the random effects model was estimated to be 6% (95% CI, 5–7) with a significant level of heterogeneity (I² = 94.4%; p < 0.001). The pooled prevalence of visual impairment due to refractive was analyzed by subtypes, and pooled prevalence was estimated to be 4%, 5.2%, and 1% for myopia, hyperopia, and astigmatism, respectively.

Conclusion

The pooled prevalence of visual impairment due to refractive error was high in Ethiopia. About one in twenty-five Ethiopian children and adolescents are affected by visual impairment due to myopia.

Greenness Surrounding Schools and Visual Impairment in Chinese Children and Adolescents

BACKGROUND

Evidence concerning the effects of greenness on childhood visual impairment is scarce.

OBJECTIVES

We aimed to assess whether greenness surrounding schools was associated with visual impairment prevalence and visual acuity levels in Chinese schoolchildren and whether the associations might be explained by reduced air pollution.

METHODS

In September 2013, we recruited 61,995 children and adolescents 6-18 years of age from 94 schools in seven provinces/municipalities in China. Greenness exposure was assessed using the normalized difference vegetation index (NDVI) and the soil-adjusted vegetation index (SAVI) from July to August 2013. Visual impairment was defined as at least one visual acuity level (dimensionless) lower than 4.9 (Snellen 5/6 equivalent). Three-year annual averages of particulate matter (PM) with an aerodynamic diameter of ≤1μm (PM1) and nitrogen dioxide (NO2) at each school were assessed using machine learning methods. We used generalized linear mixed models to estimate the associations between greenness and prevalent visual impairment and visual acuity levels and used mediation analyses to explore the potential mediating role of air pollution.

RESULTS

In the adjusted model, an interquartile range increase in NDVI500m was associated with lower odds of prevalent visual impairment [odds ratio (OR)=0.95; 95% confidence interval (CI): 0.93, 0.97]. The same increase in NDVI500m was also associated with 0.012 (95% CI: 0.008, 0.015) and 0.011 (95% CI: 0.007, 0.015) increases in visual acuity levels for left- and right-eye, respectively. Our results also suggested that PM1 and NO2 significantly mediated the association between NDVI500m and visual impairment. Similar effect estimates were observed for SAVI500m, and our estimates were generally robust in several sensitivity analyses.

DISCUSSION

These findings suggest higher greenness surrounding schools might reduce the risk of visual impairment, possibly owing in part to lower PM1 and NO2 in vegetated areas. Further longitudinal studies with more precise greenness assessment are warranted to confirm these findings. https://doi.org/10.1289/EHP8429.

Exposure to ambient air pollution and visual impairment in children: A nationwide cross-sectional study in China

Evidence concerning exposure to air pollution and visual impairment is scarce. We evaluated the associations of ambient air pollution with visual impairment and visual acuity levels in Chinese schoolchildren. We recruited 61,995 children from 7 provinces/municipalities across China. Concentrations of air pollutants (i.e., particulate matter with an aerodynamic diameter of ≤ 1.0 µm [PM₁], ≤ 2.5 µm [PM_2.5], and 10 µm [PM₁₀] as well as nitrogen dioxides [NO₂]) were measured using machine learning methods. Visual acuity levels were measured using standard protocols. We used SAS PROC SURVEYLOGISTIC to assess the association between air pollution and visual impairment. An interquartile range increase in PM₁, PM_2.5, PM₁₀, and NO₂ was associated with a 1.133- (95% CI, 1.035-1.240), 1.267- (95% CI, 1.082-1.484), 1.142- (95% CI, 1.019-1.281), and 1.276-fold (95% CI, 1.173-1.388) increased odds of visual impairment, and the associations were stronger in children being boys, older, living in rural areas, and born to parents who had a lower educational level or smoked, compared to their counterparts. These results suggest that exposure to air pollution were positively associated with the odds of visual impairment, and the association may be modified by children's age, sex, and residential area as well as parental education level and cigarette smoking.

Myopia

Myopia, also known as short-sightedness or near-sightedness, is a very common condition that typically starts in childhood. Severe forms of myopia (pathologic myopia) are associated with a risk of other associated ophthalmic problems. This disorder affects all populations and is reaching epidemic proportions in East Asia, although there are differences in prevalence between countries. Myopia is caused by both environmental and genetic risk factors. A range of myopia management and control strategies are available that can treat this condition, but it is clear that understanding the factors involved in delaying myopia onset and slowing its progression will be key to reducing the rapid rise in its global prevalence. To achieve this goal, improved data collection using wearable technology, in combination with collection and assessment of data on demographic, genetic and environmental risk factors and with artificial intelligence are needed. Improved public health strategies focusing on early detection or prevention combined with additional effective therapeutic interventions to limit myopia progression are also needed.

Does Performing the Chinese Eye Exercises Help Protect Children's Vision? - New Evidence from Primary Schools in Rural Northwestern China

Background

The high prevalence of myopia among school-age children in China has raised serious concerns about protecting Chinese students’ vision. While the regular performance of the Chinese eye exercises has been adopted as a preventive approach in China since the mid-1960s, these exercises’ effectiveness at protecting students’ vision has remained largely unknown. This study attempts to provide new evidence of the impact of regularly performing the exercises on Chinese students’ visual outcomes, based on a large-scale dataset.

Methods

A school-based survey was conducted among 9842 randomly selected students (fourth graders) from 252 primary schools in rural Northwestern China in 2012. To address potential estimation bias, we adopted both an instrumental variable (IV) approach and a bivariate-probit model to estimate the impacts on students’ visual acuity and the incidences of visual impairment and myopia.

Results

Both IV and bivariate-probit estimates reveal a detrimental impact of regularly performing the Chinese eye exercises on students’ vision. Compared with students who did not regularly perform the exercises, those who did were 6.2 percentage points more likely to have impaired vision and 7.6 percentage points more likely to be myopic. The estimates are robust to different estimation strategies, various specifications, and the majority of subsamples.

Conclusion

Under the assumption that the correct performance of the Chinese eye exercises would not undermine students’ vision, our findings suggest that the commonly-observed incorrect performance of these exercises among Chinese students imposes non-trivial threats to their vision health.

The association between menarche and myopia and its interaction with related risk behaviors among Chinese school-aged girls: a nationwide cross-sectional study

Nearly 80% of new cases of myopia arise between 9 and 13 years old when puberty development also progresses rapidly. However, little is known about the association between myopia and puberty. We aim to evaluate the association between myopia and menarche, the most important puberty indicator for girls, and to test whether menarche could modify the effects of myopia-related behaviors. The participants came from two consecutive national surveys conducted in 30 provinces in mainland China in 2010 and 2014. We included 102,883 girls (61% had experienced menarche) aged 10-15 years. Risk behaviors for myopia which included sleep duration, homework time, and outdoor activity were measured by self-administrated questionnaire. Myopia was defined according to a validated method, and its relationships with menarche status and behaviors were evaluated by robust Poisson regression models based on generalized estimated equation adjusting for cluster effect of school. We found that postmenarche girls were at 13% (95% confidence interval: 11%-16%) higher risk of myopia than premenarche girls, after adjusting for exact age, urban-rural location, survey year, and four behavioral covariates. Short sleep duration (<7 h/d), long homework time (>1 h/d) and low frequency of weekend outdoor activity tended to be stronger (with higher prevalence ratios associated with myopia) risk factors for myopia in postmenarche girls than in premenarche girls, and their interaction with menarche status was all statistically significant (P < 0.05). Overall, our study suggests that menarche onset may be associated with increased risk of myopia among school-aged girls and could also enhance girls' sensitivity to myopia-related risk behaviors.

Evaluation of the Spot Vision Screener in School-Aged Children

PURPOSE

To determine the accuracy of the Spot Vision Screener (Welch Allyn, Skaneateles Falls, NY) in children 6 years and older and recommend device thresholds to improve its accuracy for the detection of refractive error.

METHODS

The Spot Vision Screener results were compared with three gold standard conditions of increasingly narrow refractive error criterion. The sensitivity, specificity, positive predictive value, and negative predictive value of the Spot Vision Screener in detecting each gold standard criterion were calculated. The most accurate threshold setting for each parameter was identified by calculating the area under the curve receiver operating characteristic.

RESULTS

The Spot Vision Screener was able to successfully evaluate 313 of 330 children (95%). The sensitivity of the Spot Vision Screener to detect American Association for Pediatric Ophthalmology and Strabismus guidelines for amblyopia risk factors was 89.5% and the specificity was 76.7%. The sensitivity decreased to 80% and the specificity increased to 75.3% with narrower refractive criteria. The sensitivity in detecting refractive criteria improved with the proposed optimized device thresholds. Estimates for the general population indicate that the positive predictive value is reasonable at 52.3% to 61.8%, depending on the stringency of the criteria, with excellent negative predictive values.

CONCLUSIONS

In school-aged children, the primary screening focus shifts from preventing amblyopia to detecting visual disturbances, including refractive error, that may interfere with academic performance. In this age group, the Spot Vision Screener was an acceptable method of detecting significant refractive error with improved sensitivity with threshold optimization. [J Pediatr Ophthalmol Strabismus. 2020;57(3):146-153.].

Increased Time Outdoors Is Followed by Reversal of the Long-Term Trend to Reduced Visual Acuity in Taiwan Primary School Students

PURPOSE

To investigate the change in the prevalence of reduced visual acuity (VA) in Taiwanese school children after a policy intervention promoting increased time outdoors.

DESIGN

Prospective cohort study based on the Taiwan School Student Visual Acuity Screen (TSVAS) by the Ministry of Education in Taiwan.

PARTICIPANTS

All school children from grades 1 through 6 were enrolled in the TSVAS from 2001 through 2015.

METHODS

The TSVAS requires each school in Taiwan to perform measurements of uncorrected VA (UCVA) on all students in grades 1 through 6 every half year using a Tumbling E chart. Reduced VA was defined as UCVA of 20/25 or less. Data from 1.2 to 1.9 million primary school children each year were collected from 2001 through 2015. A policy program named Tian-Tian 120 encouraged schools to take students outdoors for 120 minutes every day for myopia prevention. It was instituted in September 2010. To investigate the impact of the intervention, a segmented regression analysis of interrupted time series was performed.

MAIN OUTCOME MEASURES

Prevalence of reduced VA.

RESULTS

From 2001 to 2011, the prevalence of reduced VA of school children from grades 1 through 6 increased from 34.8% (95% confidence interval [CI], 34.7%-34.9%) to 50.0% (95% CI, 49.9%-50.1%). After the implementation of the Tian-Tian 120 outdoor program, the prevalence decreased continuously from 49.4% (95% CI, 49.3%-49.5%) in 2012 to 46.1% (95% CI, 46.0%-46.2%) in 2015, reversing the previous long-term trend. For the segmented regression analysis controlling for gender and grade, a significant constant upward trend before the intervention in the mean annual change of prevalence was found (+1.58%; standard error [SE], 0.08; P < 0.001). After the intervention, the trend changed significantly, with a constant decrease by -2.34% annually (SE, 0.23; P < 0.001).

CONCLUSIONS

Policy intervention to promote increased time outdoors in schools was followed by a reversal of the long-term trend toward increased low VA in school children in Taiwan. Because randomized trials have demonstrated outdoor exposure slowing myopia onset, interventions to promote increased time outdoors may be useful in other areas affected by an epidemic of myopia.

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.

Sensitivity and specificity in methods for examination of the eye astigmatism

PURPOSE

We usually use objective and subjective methods for examination of the eye astigmatism in optometry, respectively ophthalmology. Objective methods enable to measure sphere-cylindrical refraction of the eye. If we want to prescribe new glasses or contact lenses we usually use subjective methods. The aim of this study was to measure sensitivity and specificity of some subjective and objective methods for examination of the eye astigmatism. We supposed that automatic objective refraction will be the most exact method so we choose this method as the reference method. For comparison we chose subjective methods Jackson crossed cylinders (JCC), fogging method (FM) and objective method Spot Vision Screener (SVS, WelschAllyn).

MATERIALS AND METHODS

We had in total 30 subjects with average age 23 years (SD 1 year) in our study. We made each measurement per eye separately and it was independent measurement so we could use measurement from each eye (n = 60). Each eye was firstly measured by subjective method FM, followed by JCC method and finally was use objective method Spot Vision Screener (SVS, WelschAllyn). Measurement with objective instrument TRK-1P (TOPCON) was use as reference measurement. The significance level was set at p = 0.05.

RESULTS

In variable FM we measured sensitivity 76.2 % and specificity 66.7 %. Criterion for positive finding was -0.25 D. Result was statistically significant on level p &lt; 0.001. In variable JCC we measured sensitivity 95.2 % and specificity 66.7 %. Criterion for positive finding was -0.25 D. Result was statistically significant on level p &lt; 0.001. In variable SVS we measured sensitivity 47.6 % and specificity 94.4 %. Criterion for positive finding was -0.75 D. Result was statistically significant on level p &lt; 0.001. Direct comparison of all methods showed statistically important difference between techniques JCC and FM (p = 0.0095). In other method we did not find statistically important difference (FM vs. SVS, p = 0.526 and JCC vs. SVS, p = 0.105).

CONCLUSION

All subjective and objective techniques were statistically significant in detection of eye astigmatism. Comparison of ROC curves showed statistically significant difference between FM and JCC technique. The JCC method showed the highest sensitivity, whereas SVS highest specificity.

Association of Visual Impairment With Economic Development Among Chinese Schoolchildren

IMPORTANCE

Few studies have reported the association of economic growth with trends of visual impairment in schoolchildren in China or elsewhere.

OBJECTIVES

To describe 30-year trends and patterns in visual impairment in China and to explore the association between visual impairment and economic development.

DESIGN, SETTING, AND PARTICIPANTS

In this time series analysis of 7 successive cross-sectional surveys from 1985 to 2014, a total of 1 951 084 schoolchildren aged 7 to 18 years from all provinces and autonomous regions of mainland China, excluding Tibet, were studied. In 1985, the survey was conducted between March to June; In 1991-2014, the surveys were conducted between September and November. Data analysis was performed from April 1, 2018, to January 31, 2019.

EXPOSURES

The province-level gross domestic product (GDP) per capita was extracted from the China Statistical Yearbook.

MAIN OUTCOMES AND MEASURES

Visual impairment, defined as unaided distance visual acuity of worse than 6/7.5 (20/25 Snellen equivalent), and moderate to severe visual impairment, defined as unaided distance visual acuity of worse than 6/18 (20/63 Snellen equivalent), in the worse eye.

RESULTS

A total of 1 951 084 participants (mean [SD] age, 12.6 [3.4] years; 50.5% male) were included in the analysis. Among students aged 7 to 18 years, the prevalence of visual impairment increased from 23.7% (95% CI, 23.6%-23.8%) in 1985 to 35.1% (95% CI, 34.9%-35.3%) in 1995 to 55.0% (95% CI, 54.8%-55.3%) in 2014. In 2014, the prevalence was higher among girls (58.3%; 95% CI, 54.8%-55.3%) vs boys (51.8%; 95% CI, 51.5%-52.1%) (prevalence ratio [PR] girls vs boys, 1.12; 95% CI, 1.11-1.13) and among students living in urban (59.9%; 95% CI, 59.6%-60.2%) vs rural (50.2%; 95% CI, 49.9%-50.5%) areas (PR urban vs rural, 1.17; 95% CI, 1.16-1.18), although a more rapid relative increase in prevalence occurred in rural areas (15.3% in 1985 to 50.2% in 2014) than in urban areas (31.5% in 1985 to 59.9% in 2014). From 1995 to 2014, the GDP in China increased from $1263 to $7594 (in 2014 US$ constant price). After demographic characteristics (cluster effect of school, age, sex, urban vs rural location, and relative socioeconomic status within province) were adjusted for, the regression model revealed that every 100% increase in GDP was associated with a 20% (PR, 1.20; 95% CI, 1.20-1.21) increase in the relative risk of visual impairment and a 27% (PR, 1.27; 95% CI, 1.26-1.27) increase in the relative risk of moderate to severe visual impairment. The association was stronger in male (PR, 1.22; 95% CI, 1.21-1.23 for male [as reference] vs 1.19; 95% CI, 1.18-1.19 for female; P < .001), rural (PR, 1.32; 95% CI, 1.31-1.33 for rural [as reference] vs 1.12; 95% CI, 1.12,-1.33 for urban; P < .001), and younger age groups (PR, 1.27; 95% CI, 1.24-1.29 for 7-9 years of age [as reference] vs 1.34; 95% CI, 1.32-1.36 for 10-12 years of age; P < .001; 1.21; 95% CI, 1.20-1.22 for 13-15 years of age; P < .001; and 1.12; 95% CI, 1.11,-1.13 for 16-18 years of age; P < .001).

CONCLUSIONS AND RELEVANCE

The rapid increase of visual impairment prevalence and the association between GDP and visual impairment over time suggest that further exacerbation of childhood visual impairment may occur as economic development continues in China.

Using Decision Curve Analysis to Evaluate Common Strategies for Myopia Screening in School-Aged Children

Purpose: To evaluate common strategies for screening myopia. Methods: A total of 2,248 children aged 6 to 12 years from five randomly selected primary schools were included for the screening. Enrolled study participants underwent distant uncorrected visual acuity (UCVA, Standard Logarithmic Visual Acuity E Chart) and non-cycloplegic auto-refraction (NCAR, Topcon KR-8800). Among them, 1,639 children (72.9%) accepted cycloplegic auto-refraction. Taking rejection of cycloplegia into account, receiver operating characteristic curves were drawn to compare the accuracies of the four strategies (I, Cycloplegic auto-refraction; II, NCAR; III, UCVA; IV, Combination of UCVA and NCAR). Decision curve analysis (DCA) was used to compare net benefits. Tenfold cross-validation was used for statistical analyses. Results: For myopia (spherical equivalent refraction, SE ≤ -0.5D) screening, the mean sensitivities were 73.79% (SD: 5.40%), 85.57% (6.84%), 59.71% (13.49%), and 85.06% (6.68%) for Strategy I to IV; with mean specificities of 100% (0%), 87.43% (4.27%), 89.74% (10.25%), and 88.65% (5.07%), respectively. For screening early myopia (SE ≤ -0.5D and ≥-1.0D), the mean sensitivities were 73.44% (7.69%), 82.39% (5.32%), 54.27% (14.58%), and 81.76% (9.60%) for Strategy I to IV; with mean specificities of 100% (0%), 79.13% (4.86%), 85.48% (9.86%), and 81.17% (4.16%). Based on DCA, the net benefits of Strategy IV were the highest, with the probability thresholds ranging from 12% to 50%, after adjusting the TestHarms. For early myopia, the net benefits of Strategy IV were the highest with the probability threshold ranging from 5% to 34%. Conclusion: Combination of UCVA and NCAR produced the highest net benefits for myopia screening.

Myopia screening: combining visual acuity and noncycloplegic autorefraction

PURPOSE

To explore the effectiveness of combining uncorrected visual acuity (UCVA) and noncycloplegic autorefraction (NCAR) for large-scale myopia screening in schoolchildren with a high prevalence of myopia.

METHODS

A total of 1687 children aged between 6 and 12 years, from five primary schools in the Baoshan district of Shanghai participated in the study. We measured UCVA and autorefraction before and after cycloplegia by a Topcon KR-8800. We drew receiver operating characteristic curves to achieve the best cutoff points and their corresponding sensitivities and specificities for the UCVA and NCAR, respectively. We then combined the UCVA and NCAR in serial order to explore the optimal criterion and its effectiveness. A specificity of 90% was set to compare the sensitivities among the three tests. The children were divided into three age groups (aged 6 to 7, 8 to 10, 11 to 12 years) to further examine this new method.

RESULTS

A total of 1639 children with an average age of 9.35 (SD, 1.6) years were finally included, among which 428 (26.11%) children were diagnosed as being myopic (spherical equivalent refraction (SER) less than or equal to -0.5 diopters [D]). For the UCVA, the cutoff point is 0.2 logarithm of the minimum angle of resolution (20/32), with a sensitivity and specificity of 63.6% and 94.0%, respectively. For NCAR, the cutoff point is SER less than or equal to -0.75 D, with a sensitivity and specificity of 88.6% and 86.1%, respectively. When UCVA is combined with NCAR, the best cutoff point is UCVA less than or equal to 0 logarithm of the minimum angle of resolution (20/20) and SER less than or equal to -0.75 D, with a sensitivity and specificity of 84.4% and 90.5%, respectively. At a specificity of 90%, the sensitivities are 63.55%, 78.50%, and 84.35%, respectively, for UCVA, NCAR, and the combination test. In all age groups, the combination test had the highest sensitivities among the three tests.

CONCLUSIONS

In a population with a high prevalence of myopia, combining the UCVA and NCAR in serial order achieved higher sensitivity than either of the two tests alone, when specificity was set at 90%.

Increases in the prevalence of reduced visual acuity and myopia in Chinese children in Guangzhou over the past 20 years

BACKGROUND/AIMS

To estimate the prevalence of myopia based on reduced unaided visual acuity (VA) in Chinese school children over the past 20 years.

METHODS

Guangzhou school health authorities have measured VA on Grade 1-12 students from 1988 to 2007 annually, using a LogMAR tumbling E chart. VA is reported as Snellen categories: normal (VA ≥ 6/6), mildly reduced (6/9 < VA <6/6), moderately reduced (6/18 < VA ≤ 6/9), and severely reduced VA (VA ≤ 6/18).

RESULTS

In 1988, over 80% of children in Grade 1 (age 6 years) and about 30% in Grade 12 (age 17 years) had normal unaided VA. By 2007, this dropped to only 60% in Grade 1 and about 10% in Grade 12. Conversely, the prevalence of moderately and severely reduced unaided VA increased from 6.2% in Grade 1 and 62.5% in Grade 12 in 1988 to 14.5% in Grade 1 and 84.11% in Grade 12 in 2007. This rate was unchanged from 2003 to 2007 at both the Grade 1 and Grade 12 levels.

CONCLUSIONS

In Guangzhou, the prevalence of reduced unaided VA has increased markedly in the past 20 years, but has stabilized in the past few years. This increase may result from environmental changes, such as increased schooling intensity and urbanization.

Normal and diseased personal eye modeling using age-appropriate lens parameters

Personalized eye modeling of normal and diseased eye conditions is attractive due to the recent availability of detailed ocular measurements in clinic environments and the promise of its medical and industrial applications. In the customized modeling, the optical properties of the crystalline lens including the gradient refractive index, the lens bio-geometry and orientation are typically assigned with average lens parameters from literature since typically they are not clinically available. Although, through the optical optimization by assigning lens parameters as variables, the clinical measured wavefront aberration can be achieved, the optimized lens biometry and orientation often end up at edges of the statistical distribution. Without an effective validation of these models today, the fidelity of the final lens (and therefore the model) remains questionable. To develop a more reliable customized model without detailed lens information, we incorporate age-appropriate lens parameters as the initial condition of optical optimization. A biconic lens optimization was first performed to provide a correct lens profile for accurate lower order aberration and then followed by the wavefront optimization. Clinical subjects were selected from all ages with both normal and diseased corneal and refractive conditions. 19 ammetropic eyes ( + 4D to -11D), and 16 keratoconus eyes (mild to moderate with cylinder 0.25 to 6D) were modeled. Age- and gender-corrected refractive index was evaluated. Final models attained the lens shapes comparable to the statistical distribution in their age.

Visual acuity measures do not reliably detect childhood refractive error--an epidemiological study

Purpose

To investigate the utility of uncorrected visual acuity measures in screening for refractive error in white school children aged 6-7-years and 12-13-years.

Methods

The Northern Ireland Childhood Errors of Refraction (NICER) study used a stratified random cluster design to recruit children from schools in Northern Ireland. Detailed eye examinations included assessment of logMAR visual acuity and cycloplegic autorefraction. Spherical equivalent refractive data from the right eye were used to classify significant refractive error as myopia of at least 1DS, hyperopia as greater than +3.50DS and astigmatism as greater than 1.50DC, whether it occurred in isolation or in association with myopia or hyperopia.

Results

Results are presented from 661 white 12-13-year-old and 392 white 6-7-year-old school-children. Using a cut-off of uncorrected visual acuity poorer than 0.20 logMAR to detect significant refractive error gave a sensitivity of 50% and specificity of 92% in 6-7-year-olds and 73% and 93% respectively in 12-13-year-olds. In 12-13-year-old children a cut-off of poorer than 0.20 logMAR had a sensitivity of 92% and a specificity of 91% in detecting myopia and a sensitivity of 41% and a specificity of 84% in detecting hyperopia.

Conclusions

Vision screening using logMAR acuity can reliably detect myopia, but not hyperopia or astigmatism in school-age children. Providers of vision screening programs should be cognisant that where detection of uncorrected hyperopic and/or astigmatic refractive error is an aspiration, current UK protocols will not effectively deliver.

Performance measures of the illiterate E-chart vision-screening test used in Northern District Israeli school children

Objectives

To evaluate the screening performance of 6/6 and 6/12 vision cut-offs with an illiterate E-chart implemented by a public health nurse to test children for ocular abnormalities and uncorrected refractive error. The gold standard diagnosis is an eye examination performed by an ophthalmologist.

Setting

A cross-sectional population-based study was conducted among 2113 students' ages 6–7 and 13–14 years old in 70 Northern District Israeli schools.

Methods

Students were tested by nurses and ophthalmologists. A nurse examination was carried out using the illiterate E-chart for vision measurement. The medical examination included vision history, clinical eye examination, vision and retinoscopy testing. The Physician's evaluation of whether students needed a referral for diagnostic procedures, treatment and/or follow-up was recorded. Screening test's performance was determined using ophthalmologist's decision regarding referral as the gold standard. Detection rate (DR), false-positive rate (FPR), odds affected positive result (OAPR), positive predictive value (PPV) and negative predictive value (NPV) were estimated overall and by students' demographic characteristics.

Results

For vision >6/6 cut-off in at least one eye (eyes tested separately): DR – 71.9% (95% CI 65.8–78.7%), FPR – 22.8% (95% CI 17.9–28.9%), OAPR – 0.98:1 (95% CI 0.84:1–1.15:1), PPV – 52.7% (95% CI 45.4–61.2%), NPV – 90.9% (95% CI 88.7–93.1%). For 6/12 vision cut-off, namely vision 6/12 or worse in both eyes (tested separately): DR – 58.6 (95% CI 51.8–66.4%), FPR – 15.2% (95% CI 10.9–21.1%), OAPR – 1.13:1 (95% CI 0.94:1–1.35:1), PPV – 61.1% (95% CI 52.9–70.6%), NPV – 87.6% (95% CI 84.9–90.4%).

Conclusions

Vision-screening test performance measures are mild. It is suggested to change vision cut-off level that denotes vision abnormality from current policy of vision not equal 6/6 in both eyes (tested separately) to vision 6/12 or worse in both eyes (tested separately). This change will result in reduction of FPR from 22% to 15%, concomitant with an increase in false-negative rate from 28% to 41%. Students may be equally screened by either a senior or a less experienced nurse.

Inferring myopia over the lifecourse from uncorrected distance visual acuity in childhood

AIM

To report the usefulness of uncorrected distance visual acuity (DVA) at 16 years to "screen" for myopia status and to assess the lifetime risk of myopia, based on a national birth cohort.

METHODS

1867 members of the 1958 British birth cohort for whom there were data on acuity at 16 years had autorefraction, as part of a biomedical survey, at 45 years. Reduced uncorrected DVA at age 16 years (6/12 or worse in both eyes) was compared with adult refraction (spherical equivalent).

RESULTS

Only a quarter of individuals in the population studied who had developed myopia by 45 years of age had reduced acuity at 16 years of age. Notably, half of all adults with moderate myopia (-2.99 to -5.99) and 31% (11/35) with severe myopia (> or =-6) had good uncorrected DVA in both eyes at 16 years of age. Thus, sensitivities were low, ranging from 16% for all myopia (cut-off point spherical equivalent -0.5) to 69% for severe myopia (cut-off point spherical equivalent -6). However, a high (91%) lifetime probability of primary myopia (spherical equivalent > or =-0.5) given a reduced uncorrected DVA at 16 years was found.

CONCLUSION

In this population, reduced uncorrected DVA in childhood is an inaccurate and inappropriate intermediate "phenotype" for capturing adult myopia status. However, our findings support assessment of DVA in secondary school children as an effective method of identifying refractive error (both myopia and hypermetropia).

Visual acuity and the causes of visual loss in a population-based sample of 6-year-old Australian children

PURPOSE

To describe the distribution of visual acuity and causes of visual loss in a representative sample of Australian schoolchildren.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

One thousand seven hundred thirty-eight predominantly 6-year old children examined during 2003 to 2004.

METHODS

Logarithm of the minimum angle of resolution (logMAR) visual acuity was measured in both eyes before and after pinhole correction and with spectacles if worn. Cycloplegic autorefraction (cyclopentolate) and detailed dilated fundus examination were performed.

MAIN OUTCOME MEASURES

Visual impairment was defined as any (visual acuity <20/40; <40 letters) or severe (visual acuity < or =20/200; 0-5 letters) for both better and worse eyes. Myopia was defined as spherical equivalent (SE) refraction < or =-0.50 diopters (D), and hyperopia as SE refraction > or =+2.0 D, deemed significant when > or =+3.0 D. Astigmatism was defined as cylinder > or =1.0 D and anisometropia as SE refraction difference between eyes at least 1.0 D. Amblyopia was defined as corrected visual acuity <0.3 logMAR units (<20/40; <40 letters) in the affected eye not attributable to any underlying structural abnormality of the eye or visual pathway, together with a 2-logMAR line difference between the eyes and presence of an amblyogenic risk factor.

RESULTS

The mean visual acuity of this sample was 20/25 (49.3 letters). Uncorrected visual impairment was found in the better eye of 23 children (1.3%) and in the worse eye of 71 children (4.1%). The prevalence was higher in girls than boys and among children of lower socioeconomic status. Refractive error was the most frequent cause, accounting for 69.0%, followed by amblyopia (22.5%). Astigmatism was the principle refractive error causing visual impairment and was frequently uncorrected. Presenting visual impairment (using current glasses if worn) was found in the better and worse eyes of 15 children (0.9%) and 54 children (2.8%), respectively. This was mainly due to under corrected or uncorrected refractive error.

CONCLUSIONS

This study has documented a relatively low prevalence of visual impairment in a population of Australian children. Uncorrected astigmatism and amblyopia were the most frequent causes.

Screening for myopia and refractive errors using LogMAR visual acuity by optometrists and a simplified visual acuity chart by nurses

PURPOSE

To compare the sensitivity and specificity of a widespread method of screening for refractive errors in Singapore schoolchildren using a simplified acuity screening chart with a more rigorous method using the Early Treatment Diabetic Retinopathy Study (ETDRS) chart. A secondary aim is to estimate the best cutoff values for the detection of refractive errors using these two methods.

METHODS

This is a population-based study, involving 1779 schoolchildren from three schools in Singapore. Logarithm of the minimum angle of resolution (logMAR) visual acuity was recorded using a modified Bailey-Lovie chart by trained optometrists, and visual acuity measurement was also undertaken using a simplified 7-line visual acuity screening chart by school health nurses. The main outcome measures were the receiver-operating characteristics (ROC's) of logMAR and the simplified screening visual acuity to detect myopia or any refractive errors. The difference between measurements, simplified screening visual acuity--logMAR visual acuity, was calculated.

RESULTS

The optimal threshold using the simplified screening visual acuity chart for the detection of myopia or any refractive error was 6/12 or worse. Using logMAR visual acuity, the most efficient threshold for the detection of myopia was 0.26, but this was 0.18 for the detection of any refractive error. The area under the ROC curves was significantly greater in the case of the logMAR visual acuity measurement compared with the simplified screening visual acuity measurement for the detection of myopia or any refractive errors. The 95% limits of agreement for the two methods (simplified screening--logMAR acuity) was -0.219 to +0.339.

CONCLUSIONS

Bearing in mind that the visual acuity measurements were performed by two different groups of professionals, visual acuity screening using the ETDRS method appears to be more accurate than the simplified charts for the detection of myopia or any refractive errors in children.

Vision Health Care Providers?? Attitudes and Experiences with Preschool Vision Screening in Ontario

PURPOSE

The validity of preschool vision screening has been questioned in the light of the World Health Organization's criteria for determining the validity of screening programs. However, recommendations toward preschool screening have been made by a number of organizations. Given the contrasting views of screening, the purpose of this study was to examine visual health care provider experiences and attitudes toward preschool screening.

METHOD

Optometrists, public health administrators, pediatric ophthalmologists, and orthoptists were surveyed about opinions of, recommendations for, and experiences with preschool vision screening in Ontario. The survey focused on four areas, including general opinion of preschool screening, screening standards and practices, provider experience with preschool screening, and barriers to preschool screening. In addition, survey responses were broken down by regional access to health care.

RESULTS

Overall, strong support for preschool vision screening and movement toward standardization of screening practice was found among all surveyed groups. Although support for vision screening in low health care access areas was strong, providers estimated that parent compliance to screening was weaker in low access areas. Providers also reported considerable variability in vision screening practices. In addition, although the majority of providers had been involved in a screening program, the majority was no longer involved because of lack of program organization, structure, and funding. Lack of sufficient funding, public education, organization of screening, training, and government support were listed as barriers to preschool vision screening.

CONCLUSION

Providers are interested in the development of structured screening programs. However, although screening may be a way to offer some level of vision care service to low health care access areas, a number of factors need to be addressed in discussions of vision screening program standards or screening best practice. In general, preschool screening programs need to be structured, be supported, have quality control, and be evaluated.