Zagreb Amblyopia Preschool Screening Study: near and distance visual acuity testing increase the diagnostic accuracy of screening for amblyopia

Unveiling Visual Acuity in 58,712 Four-Year-Olds: Standardized Assessment Defined Normative Visual Acuity Threshold

The purpose was to define the threshold of normal visual acuity (VA), mean monocular and binocular VA, and interocular difference in the uniform cohort of healthy four-year-old children. All the children were recruited from the Croatian National Registry of Early Amblyopia Detection database. LEA Symbols® inline optotypes were used for VA testing at near and distance, binocularly and monocularly. The pass cut-off level was set to ≤0.1 logMAR. The final sample consisted of 58,712 four-year-old children. In total, 83.78% of the children had unremarkable results, and 16.22% of the children were referred to examination. Of those, 92% of the children were referred due to binocular, and 8% of the children due to monocular causes. The children referred due to binocular causes demonstrated a VA of 0.3 ± 0.24, while the children referred due to monocular causes 0.6 ± 0.21. The ROC curve analysis defined the uniform cut-off value for a normative VA of 0.78. We analyzed the largest uniform cohort of 58,712 children, and have determined normative data for binocular and monocular VA tested with gold standard logMAR chart in four-year-old children. The results presented here established no reasoning to further utilize historical protocols in testing VA in preschool children aged ≥ 4 years.

Corneal Fourier and Belin-Ambrósio Enhanced Ectasia Analysis in Healthy 4-Year-Old White Children

PURPOSE

The aim of this study was to provide normative databases of Fourier analysis (FA) and Belin-Ambrósio enhanced ectasia display (BAD) in healthy White 4-year-old emmetropic children.

METHODS

FA parameters analyzed were spherical component (SRmin), spherical eccentricity (SEcc), maximal decentration (MD), regular astigmatism at the center (Astigm. C) and periphery (Astigm. P), and irregularity (I). The parameters obtained by BAD included summary indicator BAD D, anterior corneal curvature (K1 and K2, D), maximal keratometry (Kmax, D), maximal Ambrósio relational thinnest (ART max), and pachymetric and BAD indices.

RESULTS

Eighty-nine eyes of eighty-nine 4-year-old children were included. The mean values of FA parameters were the following: SRmin 7.77, SEcc 0.600, MD 0.160, Astigm. C 0.070, Astigm. P 0.050, and I 0.019. The mean K1 and K2 in our study group were 42.92 ± 1.29 D and 43.75 ± 1.41 D, with the mean BAD D value 0.42 ± 0.67. The mean PPI min 0.629 ± 0.117, PPI max 1.059 ± 0.155, PPI avg 0.847 ± 0.103, Kmax 44.10 ± 1.39, and median of ART max 515.0 were recorded. No statistically significant differences between male and female sex in any of FA or BAD parameters were found.

CONCLUSIONS

This is the first study providing large normative data on FA and BAD in 4-year-old White emmetropic children. We proposed a cutoff D value for early ectasia and clinical keratoconus in 4-year-old children.

Effectiveness of a Recertification Vision Screening Training Module for Preschool Teachers

Background

Certified training must be provided for lay vision screeners prior to their conduct of a vision screening programme. However, the effectiveness of trained lay screeners does deteriorate over time. This study aims to evaluate the effectiveness of a recertification vision screening training module using the KieVision™ Preschool Vision Screening Kit for preschool teachers in Malaysia.

Methods

This was a randomised control trial. Fifty-nine preschool teachers previously enrolled in a Knowledge Transfer Programme were divided into a Study Group (n = 31) to receive recertification training and a Control Group (n = 28) to attend briefing sessions. Subjects was then asked to perform vision screening on 15 preschool children aged 4 years old-6 years old at their respective premises, then verified by optometrists after 2 weeks from the initial screening on the same children.

Results

A total of 894 children were screened, with the Study Group and Control Group screened 49.7% and 50.3%, respectively. There was higher validity in vision screening findings from the Study Group (sensitivity = 66.7%, positive predictive value (PPV) = 61.5%) compared to the Control Group (sensitivity = 36.0 %, PPV = 40.9%).

Conclusion

Teachers who received recertification training were more competent in detecting children's vision impairment using KieVision™ Preschool Vision Screening Kit. Thus, timely recertification training should be emphasised to ensure sustainable consistency and reliability of vision screening programmes conducted by lay vision screeners.

Macular perfusion normative data acquired with optical coherence tomography angiography in healthy four-year-old Caucasian children

BACKGROUND

The purpose of this cross-sectional study involving healthy emmetropic four-year-old Caucasian children was to provide a macular perfusion normative database acquired with optical coherence tomography angiography (OCTA). One eye of each examinee underwent OCTA imaging. The following parameters were analyzed using AngioTool Image J software: vessels area (VA), vessels density (VD), total number of junctions (TNJ), junctions density (JD), total vessel length (TVL), average vessel length (AVL), total number of endpoints (TNEP), lacunarity (L), vessel diameter index (VDI), tortuosity (T) and foveal avascular zone (FAZ). Average central macular thickness (CMT) and average central macular volume (CMV) were measured.

RESULT

Sixty-two eyes of 62 children of average age 50.4 ± 3.8 months were examined. VA, VD, and T increased from the inner towards the outer layers of the retina. The intermediate capillary plexus had the highest JD and TNEP and narrowest FAZ. Retinal sexual differentiation was supported with higher values of the retinal VA, VDI and TNEP, and chorioretinal VA, VDI and L in males. The choriocapillaris presented with the highest VD, AVL, and T and the lowest L and TNEP.

CONCLUSION

The study provides the first detailed normative database of the macular vascular network in the youngest uniform cohort of emmetropic four-year-old children.

Comparison between distance and near visual acuity in amblyopes

To compare distant visual acuity (DVA) and near visual acuity (NVA) in amblyopia and evaluate if NVA can be used to diagnose amblyopia.A retrospective study was performed on 73 patients diagnosed with amblyopia based on DVA, by measuring their NVA and comparing the DVA and NVA. The NVA was measured by Snellen chart at 30 cm and the DVA was measured by Dr Hahn vision test chart at 5m. The patients' age, type of amblyopia, spherical equivalent, the difference between spherical equivalent and the fellow eye spherical equivalent spherical, and prism diopter (PD) were evaluated and their relationship with the difference between the DVA and NVA was analyzed.The NVA was significantly better than the DVA in amblyopia (P = .000). The difference between the DVA and NVA was not significantly related to the type of amblyopia (P = .600) or the patients' age(P = .351). Also, the difference between the DVA and NVA was not significantly affected by the spherical equivalent (P = .425) or the difference between spherical equivalent and the fellow eye spherical equivalent (P = .212) in anisometropia amblyopia, and also not by the PD (P = .882) in strabismus amblyopia.In amblyopes, the NVA was better than the DVA before amblyopia treatment. The difference between the DVA and NVA was not affected by age, type of amblyopia, spherical equivalent, the difference between spherical equivalent and the fellow eye spherical equivalent spherical, or PD. Therefore, it should be taken into consideration that NVA could underestimate the severity of amblyopia and affect the accuracy at diagnosing amblyopia.

Comparison of the pediatric vision screening program in 18 countries across five continents

PURPOSE

Incorporating mass pediatric vision screening programs as part of a national agenda can be challenging. This review assessed the implementation strategy of the existing pediatric vision screening program.

METHODS

A search was performed on PubMed, EBSCO host MEDLINE Complete, and Scopus databases encompassing the past ten years for mass pediatric screening practice patterns that met the selection criteria regarding their objectives and implementation. Results were analyzed from 18 countries across five continents.

RESULTS

Eight countries (44%) offered screening for distance visual acuity only, where the majority of the countries (88%) used either Snellen or Tumbling E chart. High-income countries initiated screening earlier and applied a more comprehensive approach, targeting conditions other than reduced vision only, compared with middle-income countries. Chart-based testing was most commonly performed, with only three countries incorporating an instrument-based approach. Lack of eyecare and healthcare practitioners frequently necessitated the involvement of non-eyecare personnel (94%) as a vision screener including parent, trained staff, and nurse.

CONCLUSIONS

Implementation of a vision screening program was diverse within countries preceded by limited resources issues. Lack of professional eyecare practitioners implied the need to engage a lay screener. The limitation of existing tests to detect a broader range of visual problems at affordable cost advocated the urgent need for the development of an inexpensive and comprehensive screening tool.

Diagnostic accuracy and agreement between visual acuity charts for detecting significant refractive errors in preschoolers

BACKGROUND

Preschool vision screenings are considered to be cost-effective methods to identify children with vision disorders. The children of this age group are poor at communicating their symptoms and hence screening is mandated. This study is aimed at estimating the diagnostic accuracy and agreement of Lea, HOTV and E visual acuity charts for detecting significant refractive errors.

METHODS

A cross-sectional study was conducted, in which monocular unaided vision assessment of each study participant was performed with Lea, HOTV and E charts. Stereo acuity was measured with the Randot Preschool Test and a comprehensive eye examination including dilatation was performed. Significant refractive error was defined as hyperopia > 3.25 D, myopia > 2.00 D, astigmatism > 1.50 D, anisometropia if interocular difference > 1.00 D for hyperopia, > 3.00 D for myopia or > 1.50 D for astigmatism. Sensitivity, specificity, positive and negative predictive values were estimated. Bland-Altmann plots were generated to help identify the level of agreement between the vision charts.

RESULTS

A total of 256 eyes were analysed. Lea, HOTV and E had sensitivities of 87.8 per cent, 90.2 per cent and 90.2 per cent, respectively. Specificity and positive predictive values were better for HOTV (77.3 per cent, 65.5 per cent) and Lea (75 per cent, 62.6 per cent), compared to E chart (69.8 per cent, 58.7 per cent). Negative predictive values for Lea, HOTV and E charts were 92.8 per cent, 93.8 per cent and 93.8 per cent, respectively. Bland-Altmann analysis showed good agreement between Lea and HOTV, Lea and E, and HOTV and E visual acuity charts. The acuity difference was least between Lea and HOTV charts (0.1 logMAR). Eighty-five (33.2 per cent) eyes had significant refractive errors. Eighty (94.1 per cent) eyes were astigmatic.

CONCLUSION

The diagnostic accuracy of the visual acuity charts was high for the identification of significant refractive errors in preschool children. There was very good agreement between the visual acuity charts.

Impact of Children's Postural Variation on Viewing Distance and Estimated Visual Acuity

Purpose

Reliable estimation of visual acuity requires that observers maintain a constant distance from the target, but use of chin rests is not always feasible. Our aim was to quantify children's movement during community testing and its impact on near (40 cm) and intermediate (150 cm) acuity measures.

Methods

Thirty-three 7-year-old children performed several acuity tests run on a tablet computer, administered in the child's home by a trained lay screener. The tablet webcam was used to derive a continuous estimate of the child's position during testing. We estimated acuity using both the recommended viewing distance and using trial-by-trial estimates of the child's physical distance from the screen.

Results

Although initial positioning in the 40-cm viewing distance condition was accurate, on 18% of trials children moved sufficiently to support a 0.1 logMAR improvement in acuity, leading 16% of staircases to overestimate acuity by more than one line. Initial positioning for the 150-cm condition was less accurate, but the longer viewing distance minimized the impact of children's movement on the visual angle of the target. Overall, at 150 cm 8% of staircases were overestimated by more than 0.1 logMAR.

Conclusions

Children move substantially during intermediate and near acuity tests despite assessors encouraging maintenance of the correct viewing distance.

Translational Relevance

Real-time estimates of the child's physical distance from the target are possible when assessments are conducted on camera-enabled devices. Correction for movement will likely lead to more accurate measures of near and intermediate visual acuity.

Global and regional estimates of prevalence of amblyopia: A systematic review and meta-analysis

Background: Amblyopia is one of the most important causes of vision impairment in the world, especially in children. Although its prevalence varies in different parts of the world, no study has evaluated its prevalence in different geographical regions comprehensively. The aim of the present study was to provide global and regional estimates of the prevalence of amblyopia in different age groups via a systematic search.Methods: In this study, international databases, including Embase, Scopus, PubMed, Web of Science, and other relevant databases, were searched systematically to find articles on the prevalence of amblyopia in different age groups published in English. The prevalence and 95% CI were calculated using binomial distribution. The Cochran's Q-test and I² statistic were applied to assess heterogeneity, a random-effects model was used to estimate the pooled prevalence, and a meta-regression method was utilized to investigate the factors affecting heterogeneity between studies.Results: Of 1252 studies, 73 studies were included in the analysis (sample volume: 530,252). Most of these studies (n = 25) were conducted in the WHO-Western Pacific Regional Office. The pooled prevalence estimate of amblyopia was 1.75% (95% CI: 1.62-1.88), with the highest estimate in European Regional Office (3.67%, 95% CI: 2.89-4.45) and the lowest in African Regional Office (0.51%, 95% CI: 0.24-0.78). The most common cause of amblyopia was anisometropia (61.64%). The I² heterogeneity was 98% (p < 0.001). According to the results of univariate meta-regression, the variables of WHO region (b: 0.566, p < 0.001), sample size (b: -0.284 × 10^-4, p: 0.025), and criteria for definition of amblyopia (b: -0.292, p: 0.010) had a significant effect on heterogeneity between studies, while age group, publication date, and cause of amblyopia had no significant effect on heterogeneity.Conclusion: The prevalence of amblyopia varies in different parts of the world, with the highest prevalence in European countries. Geographical location and criteria for definition of amblyopia are among factors contributing to the difference across the world. The results of this study can help stakeholders to design health programs, especially health interventions and amblyopia screening programs.

Normative visual acuity in Chinese preschoolers aged 36 to <48 months as measured with the linear HOTV chart: the Yuhuatai Pediatric Eye Disease Study

OBJECTIVES

To document population-based normative data for uncorrected visual acuity (UCVA) in Chinese preschoolers aged 36 to <48 months without any sight-affecting abnormalities and to evaluate its effectiveness for vision referral.

METHODS

In a population-based cohort of children in the Yuhuatai Pediatric Eye Disease Study, UCVA was measured by using the linear HOTV chart, followed by other ocular examinations. Reference population was defined as children without ophthalmic abnormalities or refractive error. Normative UCVA was obtained from the reference population. The UCVA referral cut-off was defined as the lowest fifth percentile of the normative distribution of UCVA.

RESULTS

The analysis cohort consisted of 1606 Chinese preschoolers aged 36 to <48 months. Among them, a total of 791 children were included in the reference population. The 5th, 50th and 95th percentiles of the UCVA distribution in the reference population were 20/40, 20/32 and 20/25, respectively. UCVA improved with increasing age (p<0.0001), but worsen if prematurity was presented (p=0.041). Using the fifth percentile, UCVA cut-off from the reference population generated referral rates of 26.9% in the general population, and detected more than 86% of amblyopia cases.

CONCLUSIONS

We propose that UCVA no better than 20/40 measured by linear HOTV chart should be a referral cut-off for Chinese preschoolers aged 36 to <48 months. Most amblyopia cases can be identified with this age-specific and chart-specific UCVA cut-off.

Childhood amblyopia: current management and new trends

INTRODUCTION OR BACKGROUND

With a prevalence of 2-5%, amblyopia is the most common vision deficit in children in the UK and the second most common cause of functional low vision in children in low-income countries.

SOURCES OF DATA

Pubmed, Cochrane library and clinical trial registries (clinicaltrials.gov, ISRCTN, UKCRN portfolio database).

AREAS OF AGREEMENT

Screening and treatment at the age of 4-5 years are cost efficient and clinically effective. Optical treatment (glasses) alone can improve visual acuity, with residual amblyopia treated by part-time occlusion or pharmacological blurring of the better-seeing eye. Treatment after the end of the conventional 'critical period' can improve vision, but in strabismic amblyopia carries a low risk of double vision.

AREAS OF CONTROVERSY

It is not clear whether earlier vision screening would be cost efficient and associated with better outcomes. Optimization of treatment by individualized patching regimes or early start of occlusion, and novel binocular treatment approaches may enhance adherence to treatment, provide better outcomes and shorten treatment duration.

GROWING POINTS

Binocular treatments for amblyopia.

AREAS TIMELY FOR DEVELOPING RESEARCH

Impact of amblyopia on education and quality of life; optimal screening timing and tests; optimal administration of conventional treatments; development of child-friendly, effective and safe binocular treatments.