Prevalence of Amblyopia and Refractive Errors in an Unscreened Population of Children

Artificial intelligence-based screening for amblyopia and its risk factors: comparison with four classic stereovision tests

Introduction

The development of costs-effective and sensitive screening solutions to prevent amblyopia and identify its risk factors (strabismus, refractive problems or mixed) is a significant priority of pediatric ophthalmology. The main objective of our study was to compare the classification performance of various vision screening tests, including classic, stereoacuity-based tests (Lang II, TNO, Stereo Fly, and Frisby), and non-stereoacuity-based, low-density static, dynamic, and noisy anaglyphic random dot stereograms. We determined whether the combination of non-stereoacuity-based tests integrated in the simplest artificial intelligence (AI) model could be an alternative method for vision screening.

Methods

Our study, conducted in Spain and Hungary, is a non-experimental, cross-sectional diagnostic test assessment focused on pediatric eye conditions. Using convenience sampling, we enrolled 423 children aged 3.6-14 years, diagnosed with amblyopia, strabismus, or refractive errors, and compared them to age-matched emmetropic controls. Comprehensive pediatric ophthalmologic examinations ascertained diagnoses. Participants used filter glasses for stereovision tests and red-green goggles for an AI-based test over their prescribed glasses. Sensitivity, specificity, and the area under the ROC curve (AUC) were our metrics, with sensitivity being the primary endpoint. AUCs were analyzed using DeLong's method, and binary classifications (pathologic vs. normal) were evaluated using McNemar's matched pair and Fisher's nonparametric tests.

Results

Four non-overlapping groups were studied: (1) amblyopia (n = 46), (2) amblyogenic (n = 55), (3) non-amblyogenic (n = 128), and (4) emmetropic (n = 194), and a fifth group that was a combination of the amblyopia and amblyogenic groups. Based on AUCs, the AI combination of non-stereoacuity-based tests showed significantly better performance 0.908, 95% CI: (0.829-0.958) for detecting amblyopia and its risk factors than most classical tests: Lang II: 0.704, (0.648-0.755), Stereo Fly: 0.780, (0.714-0.837), Frisby: 0.754 (0.688-0.812), p < 0.02, n = 91, DeLong's method). At the optimum ROC point, McNemar's test indicated significantly higher sensitivity in accord with AUCs. Moreover, the AI solution had significantly higher sensitivity than TNO (p = 0.046, N = 134, Fisher's test), as well, while the specificity did not differ.

Discussion

The combination of multiple tests utilizing anaglyphic random dot stereograms with varying parameters (density, noise, dynamism) in AI leads to the most advanced and sensitive screening test for identifying amblyopia and amblyogenic conditions compared to all the other tests studied.

Utilization and barriers to eye care following school-wide pediatric vision screening

OBJECTIVE

In August 2018, Ontario introduced the Child Visual Health and Vision Screening Protocol outlining school-based senior kindergarten (aged 4-6 years) vision screening. We determine the prevalence of children at risk based on screening in an Ontario community and follow up to determine resource utilization after screening.

METHODS

Vision screening data (HOTV, Randot, Autorefractor) from 41 schools (1127 children) were collected for the 2018-2019 and 2019-2020 school years. Phone follow-up was conducted 1-1.5 years after screening to determine whether an optometry visit occurred, if glasses were prescribed, and potential barriers to accessing eye care. Independent t tests were used to compare time to follow-up between groups, and χ2 testing was used for associations between material and social deprivation.

RESULTS

Overall screening resulted in a 32.2% referral rate within our region. Of the referred children who responded, the rate of seeking out eye care was 69.9% (n = 64), and 65.2% of these visits were prompted specifically by vision screening, and 34.4% of referred children respondents were prescribed glasses. There was a significant relationship between receiving a referral and living in a more materially deprived (p = 0.001) and a more socially deprived area (p = 0.006). The most frequently reported barriers were related to insufficient insurance coverage for eye care or glasses, COVID-19-related difficulties, and scheduling conflicts.

CONCLUSION

Our vision screening program identified and referred more than one third of children screened for follow-up eye examinations, with children in more deprived neighbourhoods being more frequently referred. Around two thirds of referred children sought care, and one third were prescribed glasses in the follow-up sample.

Worsening vision at age 4-5 in England post-COVID: Evidence from a large database of vision screening data

PURPOSE

Myopia prevalence has increased in the UK at age 10-16y, but little is known about younger children. We hypothesise that if the 'myopia epidemic' is affecting young children, then there will be increasing rates of bilateral reduced unaided vision (V) at vision screenings of children 4-5 years of age.

METHODS

Retrospective anonymised data from computerised vision screening at age 4-5 years were analysed from serial cross-sectional data. Refractive error is not assessed in UK vision screening, so vision was investigated. Data were only included from schools that screened every year from 2015/16 to 2021/22. The criterion used was unaided monocular logMAR (automated letter-by-letter scoring) vision >0.20 in both the right and left eyes, so as to maximise the chances of detecting bilateral, moderate myopia rather than amblyopia.

RESULTS

Anonymised raw data were obtained for 359,634 screening episodes from 2075 schools. Once schools were excluded where data were not available for every year and data were cleaned, the final database comprised 110,076 episodes. The proportion (percentage and 95% CI) failing the criterion from 2015/16 to 2021/22 were 7.6 (7.2-8.0), 8.5 (8.1-8.9), 7.5 (7.1-7.9), 7.8 (7.4-8.2), 8.7 (8.1-9.2), 8.5 (7.9-9.0) and 9.3 (8.8-9.7), respectively. The slope of the regression line showed a trend for increasing rates of reduced bilateral unaided vision, consistent with increasing frequency of myopia (p = 0.06). A decreasing linear trendline was noted for children 'Under Professional Care'.

CONCLUSIONS

For children 4-5 years of age, there were signs of reduced vision over the last 7 years in England. Consideration of the most likely causes support the hypothesis of increasing myopia. The increase in screening failures highlights the importance of eye care in this young population.

Tecnics Eyhance Iol as a Solution for Anisometropic Amblyopia Cataract Patient: a Case Report

Background

Amblyopia affects 1-3% of the population, leading to irreversible vision loss in children and adults. Treatment options include refractive correction, occlusion therapy, and atropine penalization. Anisometropic amblyopia, caused by a difference in refractive status between the eyes, can be treated using contact lenses, glasses, ICL implantation, or cataract surgery with intraocular lens implantation. Tecnis Eyhance IOL is a superior solution, improving vision after eye surgery with a low incidence of halo, glare, or starburst.

Objective

The aim is to present the case of a patient with anisometropic amblyopia, in whom Eyhance IOL was implanted in both eyes as a solution to refractive error and initial cataract due to intolerance for contact lenses.

Case report

A 58-year-old female patient presented to our clinic complaining of blurry vision in her left eye that had persisted for a year. The patient reported intolerance to contact lenses and a history of amblyopia in her right eye. CDVA was 0.20 with -9.00/-1.50 x 25◦ in her right and 0.80 with +4.00 sphere correction in her left eye, while her CNVA was J9 with +2.50 and J1 with +2.50. Slit-lamp examination revealed early cataracts in both eyes, with otherwise normal findings. A dilated fundus examination showed vitreous liquefaction and myopic macula in the right eye but normal results in both eyes' posterior segments. The IOP was within normal limits, and the eye's axial length was measured. Considering the patient's intolerance to contact lenses, cataract surgery with intraocular lens implantation was deemed appropriate. Given the anisometropic amblyopia, the Eyhance lens was selected to optimize the patient's visual acuity. Following the procedure, the patient's visual acuity improved significantly, with her best CDVA at 0.35 in the right eye and 0.95 in the left eye. With +1.50 sphere correction, the CNVA was also enhanced, with the patient reading at J4 and J1 for her right and left eye, respectively. These improvements may have positively impacted the patient's quality of life and ability to perform daily activities.

Conclusion

Anisometropic amblyopia in 58-year-old women was treated successfully with cataract surgery and implantation of Eyhance IOL.

A Comprehensive Overview of Vision Screening Programmes across 46 Countries

Purpose:

To describe and compare vision screening programmes and identify variance in number and type of tests used, timing of screening, personnel involved, monitoring and funding to be used as data for optimising, disinvesting or implementing future screening programmes.

Methods:

A questionnaire consisting of nine domains: demography & epidemiology, administration & general background, existing screening, coverage & attendance, tests, follow-up & diagnosis, treatment, cost & benefit and adverse effects was completed by Country Representatives (CRs) recruited from 47 countries.

Results:

The questionnaire was sufficiently completed for 46 Countries: 42 European countries, China, India, Malawi and Rwanda. Variation of provision was found in; age of screening (0–17 years), tests included (23), types of visual acuity (VA) test used (35 different optotypes), personnel (13), number of screens per child (median 5, range 1–32), and times VA tested (median 3, range 1–30). Infant screening is offered in all countries, whereas childhood vision screening is offered at least once in all countries, but not all regions of each country. All 46 countries provide vision screening between the ages of 3–7 years. Data on screening outcomes for quality assurance was not available from most countries; complete evaluation data was available in 2% of countries, partial data from 43%.

Conclusion:

Vision screening is highly variable. Some form of VA testing is being undertaken during childhood. Data collection and sharing should be improved to facilitate comparison and to be able to optimise vision screening programmes between regions and countries.

The Global Prevalence of Amblyopia in Children: A Systematic Review and Meta-Analysis

Epidemiological data about the prevalence of amblyopia around the world vary widely among regions and periods. This meta-analysis aimed to determine the global prevalence of amblyopia in children. PubMed, Embase, and the Cochrane Library were searched for prevalence studies published up to 5 November 2021. The outcome was the prevalence of amblyopia, analyzed as pooled estimates with 95% confidence intervals (CI). A total of 97 studies were included, including 4,645,274 children and 7,706 patients with amblyopia. The overall worldwide pooled prevalence of amblyopia was 1.36% (95%CI: 1.27-1.46%). The prevalence of amblyopia was higher in males (1.40%, 95%CI: 1.10-1.70%) than in females (1.24%, 95%CI: 0.94-1.54%) (OR = 0.885, 95%CI: 0.795-0.985, P = 0.025). The results of the meta-regression analysis showed that there were no significant associations between the prevalence of amblyopia and geographical area, publication year, age, sample size, and whether it was carried out in a developed or developing country (all P > 0.05). Begg's test (P = 0.065) and Egger's test (P < 0.001) showed that there was a significant publication bias in the prevalence of amblyopia. In conclusion, amblyopia is a significant vision problem worldwide, and public health strategies of early screening, treatment, and management are important.

Development of a Spectacle Wear Monitor System: SpecsOn Monitor

Purpose

This study aimed to custom design, build, and test a removable device that accurately and objectively monitors adherence to spectacle wear in preschool children participating in clinical trials. This work will provide researchers with the tools to investigate the effect of adherence to optical treatment in conditions relating to refractive error, such as anisometropia, amblyopia, myopia, and accommodative esotropia, where spectacle wearing behaviors are of interest.

Methods

Several sensors were considered in the design of the SpecsOn monitor. The final version included two temperature sensors, one that measures skin temperature through an infrared sensor directed at the wearer's temple on the spectacle arm and the other measuring device temperature. The difference between the two temperature readings is used to determine if the spectacles were worn. The SpecsOn monitor was tested in two phases in adult participants (laboratory n = 10 and real world n = 5).

Results

Results from both phases showed good agreement between the objective measurement of wear based on skin and device temperature differences and participants’ manually logged wear times. The custom built SpecsOn monitor was 99% successful in accurately detecting spectacle wear in our adult cohort.

Conclusions

The SpecsOn monitor offers a convenient, accurate, and reliable system to monitor spectacle adherence. The devices were comfortable, secure, and unobtrusive to wear, and fitted easily to a variety of frame styles.

Translational Relevance

Easy access to spectacle compliance information from the SpecsOn monitor during the optical treatment phase will optimize visual outcomes and provide detailed clinical data to support decision making on the need and timing of additional therapies, improving treatment efficiency.

Amblyopia risk factors among pediatric patients in a hospital-based setting using photoscreening

PURPOSE

The aim of our study was to determine the prevalence of amblyopia risk factors in children visiting the American University of Beirut Medical Center (AUBMC) using automated vision screening.

METHODS

This was a hospital-based screening of 1102 children aged between 2 and 6 years. Vision screening was performed using PlusoptiX S12 over 2 years (2018-2020). The need for referral to a pediatric ophthalmologist was based on the amblyopia risk factors set forth by the American Association for Pediatric Ophthalmology and Strabismus. Referred patients underwent a comprehensive eye examination.

RESULTS

A total of 1102 children were screened, 63 were referred for amblyopia risk factors (5.7%); 37/63 (59%) underwent comprehensive eye examination and 73% were prescribed glasses. Of the non-referred group of children, 6.35% had astigmatism, 6.25% were hyperopic and 3.27% were myopic. The refractive errors observed among the examined patients were distributed as follows: 41% astigmatism, 51% hyperopia, and 8% myopia; amblyopia was not detected. Refractive amblyopia risk factors were associated with the presence of systemic disorders. Bland-Altman plots showed most of the differences to be within limits of agreement.

CONCLUSION

Using an automated vision screener in a hospital-based cohort of children aged 2 to 6 years, the rate of refractive amblyopia risk factors was 5.7%. Hyperopia was the most commonly encountered refractive error and children with systemic disorders were at higher risk.

Scope and costs of autorefraction and photoscreening for childhood amblyopia-a systematic narrative review in relation to the EUSCREEN project data

Background

Amblyopia screening can target reduced visual acuity (VA), its refractive risk factors, or both. VA testing is imprecise under 4 years of age, so automated risk-factor photoscreening appears an attractive option. This review considers photoscreening used in community services, focusing on costs, cost-effectiveness and scope of use, compared with EUSCREEN project Country Reports describing how photo- and automated screening is used internationally.

Methods

A systematic narrative review was carried out of all English language photoscreening literature to September 10th 2018, using publicly available search terms. Where costs were considered, a CASP economic evaluation checklist was used to assess data quality.

Results

Of 370 abstracts reviewed, 55 reported large-scale community photoscreening projects. Five addressed cost-effectiveness specifically, without original data. Photoscreening was a stand-alone, single, test event in 71% of projects. In contrast, 25 of 45 EUSCREEN Country Reports showed that if adopted, photoscreening often supplements other tests in established programmes and is rarely used as a stand-alone test. Reported costs varied widely and evidence of cost-effectiveness was sparse in the literature, or in international practice. Only eight (13%) papers compared the diagnostic accuracy or cost-effectiveness of photoscreening and VA testing, and when they did, cost-effectiveness of photoscreening compared unfavourably.

Discussion

Evidence that photoscreening reduces amblyopia or strabismus prevalence or improves overall outcomes is weak, as is evidence of cost-effectiveness, compared to later VA screening. Currently, the most cost-effective option seems to be a later, expert VA screening with the opportunity for a re-test before referral.

Impaired visual acuity caused by uncorrected refractive errors and amblyopia in a German paediatric cohort

PURPOSE

This study describes the prevalence of visual impairment caused by uncorrected distance refractive error and the spectacle coverage in a large cohort of German children and adolescents. Furthermore, we determined the prevalence of amblyopia and amblyopia treatment.

METHODS

Optometrists carried out visual acuity (VA) testing, non-cycloplegic autorefraction, VA retesting with the refractive correction obtained by autorefraction, and if necessary subjective refraction and cover-test in 1,874 subjects (901 girls/973 boys), aged 3 to 16 years. Additionally, a questionnaire on the history of previous eye care was completed.

RESULTS

Distance visual impairment (VI) with VA worse than 6/18 Snellen in the better eye was present in 0.5% (95% confidence interval [95% CI]: 0.2% to 0.9%) of children. Logistic regression showed a significant positive association between VI and older age (OR = 1.21, P = 0.03). Gender differences were not found (P = 0.77). The spectacle coverage of all participants was 74.8% (95% CI: 65.2% to 82.8%). Amblyopia was found in 29 participants (1.5%; 95% CI: 1.0% to 2.2%) with no age or sex differences. The causes of unilateral amblyopia (27 cases, 93.1%) were anisometropia in 55.6% of children, strabismus in 25.9% and the combination of these factors in 18.5%. All children with bilateral amblyopia (2 cases, 6.9%) showed bilateral high ametropia. We observed 15 children with current amblyopia, who had been treated with occlusion therapy in the past (62.2%; 95% CI: 42.7% to 83.6%).

CONCLUSIONS

The prevalence of impaired VA caused by uncorrected refractive error and amblyopia is comparable with previous studies conducted in urban areas worldwide. Adding the measurement of refractive error to existing medical check-ups, possibly using autorefraction, would be desirable.

Referral outcomes from a vision screening program for school-aged children

OBJECTIVE

To assess ocular diagnoses and follow-up patterns of children referred for a comprehensive eye examination after a school-based vision screening program.

DESIGN

Retrospective chart review.

PARTICIPANTS

Students in grades K-5 from the School District of Philadelphia public schools screened by The Wills Eye Vision Screening Program for Children between January 2014 and June 2015.

METHODS

Children with subnormal best-corrected visual acuity or other ocular conditions were referred to the Wills Eye pediatric ophthalmology service. A social worker assisted parents/guardians of referred children in scheduling an appointment and navigating insurance/payment issues. Measured outcomes included demographic information, ocular diagnoses, treatments, and follow-up patterns.

RESULTS

Of 10 726 children screened, 509 (5%) were referred for a follow-up eye examination. Of these 509 children, only 127 (25%) completed a referral eye examination with parental consent. Most children (58%) were diagnosed with more than one eye condition, including refractive error (76%), amblyopia (43%), strabismus (16%), and anisometropia (13%). Other conditions included macular hypoplasia, ptosis, and other congenital anomalies.

CONCLUSIONS

This program discovered and addressed potentially vision-threatening conditions in underserved children susceptible to amblyopia by offering social worker services and financial support to enable referred children to complete an eye examination. Contact by the social worker required consent. Obtaining such consent proved to be a barrier to connecting children with the recommended consultation.

Prevalence and pattern of amblyopia in a rural hospital in Ghana

Amblyopia is a developmental ocular disease of childhood-onset which may lead to persistent sequelae into adulthood. Early detection and management of amblyopia usually result in an improved visual outcome. The purpose of this study was to determine the prevalence and pattern of amblyopia in a rural hospital in Ghana. Clinical records of patients seen (from January 2014 to December 2018) at Westphalian Medical Center, Oyoko, Ashanti Region, Ghana, were reviewed retrospectively. Unilateral amblyopia was defined as a two-line interocular difference or more in visual acuity. Bilateral amblyopia was defined as best-corrected visual acuity (BCVA) of Snellen 6/12 or worse in both eyes, with evidence of bilateral ametropia or obstruction of the visual pathway. Following a review of 12,602 patient records, 258 cases of amblyopia were identified. The mean (±SD) presenting age of amblyopic patients was 24.3 ± 16.1 years, with a male-to-female ratio of 1:1.1. The period prevalence of amblyopia was 2.04%. The period prevalence of unilateral and bilateral amblyopia was 1.38% and 0.66%, respectively. The most prevalent form of amblyopia was refractive with a cumulative prevalence of 1.42%. Strabismic and stimulus deprivation amblyopia accounted for 0.36% and 0.21% of all amblyopic cases, respectively. A major cause of amblyopia in this population was refractive error, hence the use of spectacle correction for its initial management. Repeated assessment after an appropriate period of refractive adaptation would elucidate the proportion of amblyopias needing additional treatment modalities. Vision screening for early detection of amblyopia in childhood with accessible and effective management of amblyopia (including refractive correction and occlusion treatment) is necessary to reduce the impact of amblyopia in Ghana.

Muenke syndrome: long-term outcome of a syndrome-specific treatment protocol

OBJECTIVE

The authors evaluated the long-term outcome of their treatment protocol for Muenke syndrome, which includes a single craniofacial procedure.

METHODS

This was a prospective observational cohort study of Muenke syndrome patients who underwent surgery for craniosynostosis within the first year of life. Symptoms and determinants of intracranial hypertension were evaluated by longitudinal monitoring of the presence of papilledema (fundoscopy), obstructive sleep apnea (OSA; with polysomnography), cerebellar tonsillar herniation (MRI studies), ventricular size (MRI and CT studies), and skull growth (occipital frontal head circumference [OFC]). Other evaluated factors included hearing, speech, and ophthalmological outcomes.

RESULTS

The study included 38 patients; 36 patients underwent fronto-supraorbital advancement. The median age at last follow-up was 13.2 years (range 1.3-24.4 years). Three patients had papilledema, which was related to ophthalmological disorders in 2 patients. Three patients had mild OSA. Three patients had a Chiari I malformation, and tonsillar descent < 5 mm was present in 6 patients. Tonsillar position was unrelated to papilledema, ventricular size, or restricted skull growth. Ten patients had ventriculomegaly, and the OFC growth curve deflected in 3 patients. Twenty-two patients had hearing loss. Refraction anomalies were diagnosed in 14/15 patients measured at ≥ 8 years of age.

CONCLUSIONS

Patients with Muenke syndrome treated with a single fronto-supraorbital advancement in their first year of life rarely develop signs of intracranial hypertension, in accordance with the very low prevalence of its causative factors (OSA, hydrocephalus, and restricted skull growth). This illustrates that there is no need for a routine second craniofacial procedure. Patient follow-up should focus on visual assessment and speech and hearing outcomes.

Comparison of amblyopia in schoolchildren in Ireland and Northern Ireland: a population-based observational cross-sectional analysis of a treatable childhood visual deficit

OBJECTIVES

This study reports the prevalence of persistent amblyopia (post-traditional treatment age) in schoolchildren in the Republic of Ireland (henceforth Ireland) and Northern Ireland (NI), UK; populations with broadly similar refractive and genetic profiles but different eye-care systems.

DESIGN

This is a population-based observational study of amblyopia and refractive error.

SETTING

Recruitment and testing in primary and post-primary schools in Ireland and NI.

PARTICIPANTS

Two groups identified through random cluster sampling to represent the underlying population; Ireland 898 participants (12-13 years old) and NI 723 participants (295 aged 9-10 years old, 428 aged 15-16 years old).

MAIN OUTCOME MEASURES

Monocular logMAR visual acuity (presenting and pinhole), refractive error (cycloplegic autorefraction), ocular alignment (cover test) and history of previous eye care. These metrics were used to determine prevalence and type of amblyopia and treatment histories.

RESULTS

Children examined in NI between 2009 and 2011 had a significantly lower amblyopia prevalence than children examined in Ireland between 2016 and 2018 (two-sample test of proportions, p<0.001). Using a criteria of pinhole acuity 0.2logMAR (6/9.5 Snellen) plus an amblyogenic factor, 4 of 295 participants aged 9-10 years old (1.3%, 95% CIs 0.4 to 3.6) and 3 of 428 participants aged 15-16 years old (0.7%, 95%CIs 0.2 to 2.2) were identified in NI. The corresponding numbers in Ireland were 40 of 898 participants aged 12-13 years old (4.5%, 95% CI 3.2 to 6.1). In NI strabismic amblyopia was the most prevalent type of persistent amblyopia, whereas anisometropic was predominant in Ireland. In Ireland, amblyopia was associated with socioeconomic disadvantage (OR=2.2, 95%CIs 1.4 to 3.6, p=0.002) and poor spectacle compliance (OR 2.5, 95% CIs 2.0 to 3.2, p<0.001).

CONCLUSIONS

Amblyopia prevalence persisting beyond traditional treatment ages was significantly lower among NI children compared with Ireland. Uncorrected anisometropia, compliance with spectacle wear and socioeconomic disadvantage were contributing factors in Ireland. Children without obvious visible eye defects were less likely to access eye care in Ireland, resulting in missed opportunities for intervention where necessary.

Prevalence of amblyopia in Bulgaria

Introduction: The purpose of this study was to establish the prevalence of amblyopia in children, aged 4 to 10 years, in Bulgaria, who underwent a complete eye examination.Methods: The study was designed as cross-sectional epidemiological study, and the results were calculated in percentages. A complete ophthalmological examination was performed on 1,675 children, aged 4 to 10 years (mean age 7.7 years), during the period 01 Feb 2017-21 April 2017, in five cities, in the western part of Bulgaria. All children were verbal, none of them had a neurologic deficit or mental development delay and a complete examination was successfully performed. The ophthalmological examination consisted of: autorefractometry (using pediatric autorefractor with infrared photoretinoscopy), visual acuity, best-corrected visual acuity (BCVA) and visual acuity with pinhole occluder, cover/uncover and alternate cover test, Worth four-dot test, stereopsis, biomicroscopy and funds examination. Amblyopia was defined as reduction of the BCVA for near and far distances under 40/60 on one or on both eyes in the absence of any pathology of the eye, excluding a pathology leading to stimulus deprivation amblyopia, and in the presence of an amblyogenic factor.Results: Out of 1,675 children, 42 (2.5%) were diagnosed with amblyopia: 7% had strabismic amblyopia (3), 59% had anisometropic amblyopia (25), 31% had isoametropic amblyopia (13), and 3% deprivation amblyopia (1). Unilateral amblyopia was diagnosed in 73% (27) of the cases and bilateral amblyopia in 27% (15). For 45% (754) of the children, it was their first visit to an ophthalmologist.Conclusions: The prevalence of amblyopia among these patients (2.5%) is correlating well with the expected, based on data from other authors, between 1.5% and 3.5%. The fact that nearly half of the children (45%) have not been examined by an ophthalmologist is, however, alarming. The lack of a national screening program in Bulgaria could be the main reason. Other factors include: insufficient number of pediatric ophthalmologists in the country and the lack of awareness among the parents.

Validation of dynamic random dot stereotests in pediatric vision screening

PURPOSE

Stereo vision tests are widely used in the clinical practice for screening amblyopia and amblyogenic conditions. According to literature, none of these tests seems to be suitable to be used alone as a simple and reliable tool. There has been a growing interest in developing new types of stereo vision tests, with sufficient sensitivity to detect amblyopia. This new generation of assessment tools should be computer based, and their reliability must be statistically warranted. The present study reports the clinical evaluation of a screening system based on random dot stereograms using a tablet as display. Specifically, a dynamic random dot stereotest with binocularly detectable Snellen-E optotype (DRDSE) was used and compared with the Lang II stereotest.

METHODS

A total of 141 children (aged 4-14, mean age 8.9) were examined in a field study at the Department of Ophthalmology, Pécs, Hungary. Inclusion criteria consisted of diagnoses of amblyopia, anisometropia, convergent strabismus, and hyperopia. Children with no ophthalmic pathologies were also enrolled as controls. All subjects went through a regular pediatric ophthalmological examination before proceeding to the DRDSE and Lang II tests.

RESULTS

DRDSE and Lang II tests were compared in terms of sensitivity and specificity for different conditions. DRDSE had a 100% sensitivity both for amblyopia (n = 11) and convergent strabismus (n = 21), as well as a 75% sensitivity for hyperopia (n = 36). However, the performance of DRDSE was not statistically significant when screening for anisometropia. On the other hand, Lang II proved to have 81.8% sensitivity for amblyopia, 80.9% for strabismus, and only 52.8% for hyperopia. The specificity of DRDSE was 61.2% for amblyopia, 67.3% for strabismus, and 68.6% for hyperopia, respectively. Conversely, Lang II showed about 10% better specificity, 73.8% for amblyopia, 79.2% for strabismus, and 77.9% for hyperopia.

CONCLUSIONS

The DRDSE test has a better sensitivity for the detection of conditions such as amblyopia or convergent strabismus compared with Lang II, although with slightly lower specificity. If the specificity could be further improved by optimization of the stimulus parameters, while keeping the sensitivity high, DRDSE would be a promising stereo vision test for screening of amblyopia.

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.

The burden of pure anisometropic amblyopia: a cross-sectional study on 2800 Iranians

PURPOSE

To assess the proportion of pure anisometropic amblyopia in a sample Iranian (white) population.

METHODS

A total of 2800 consecutive individuals who presented at a referral eye clinic for any reason were examined for the presence of pure anisometropic amblyopia. Anisometropia was reported when a spherical equivalent refraction difference of at least 1.0 D with or without a cylinder refraction difference of at least 1.0 D was present between the two eyes. Amblyopia was defined as the best-corrected visual acuity of 20/30 or worse or a two-line interocular visual acuity difference between eyes that could not be attributed to any structural ocular pathology or visual pathway abnormality.

RESULTS

Subjects were 1528 females and 1272 males with a mean age of 30.25 ± 14.93 years (range, 5-65). Amblyopia was diagnosed in 192 cases (6.9%), significantly more frequent among females (7.9 vs. 5.7%, p = 0.02). Pure anisometropic amblyopia was present in 6.1% of the study population, significantly more common in patients with spherical hyperopic anisometropia (37.7%) compared to patients with spherical myopic anisometropia (21.3%), cylindrical myopic anisometropia (4.1%), and cylindrical hyperopic anisometropia (15%) (p < 0.001).

CONCLUSIONS

Pure anisometropic amblyopia is a common finding in Caucasians seeking eye care, particularly when anisometropia is of spherical hyperopic subtype.

The prevalence of amblyopia in Germany: data from the prospective, population-based Gutenberg Health Study

BACKGROUND

Amblyopia is due to insufficient development of the visual system in early childhood and is a major source of lifelong impairment of visual acuity. Too little is known about the prevalence of amblyopia in Germany and the frequency of its various causes.

METHODS

The Gutenberg Health Study of the University of Mainz Faculty of Medicine is an ongoing population-based, prospective, monocentric cohort study with 15 010 participants aged 35 to 74. All participants are examined for the presence of ocular, cardiovascular, neoplastic, metabolic, immunologic, and mental diseases. 3227 participants aged 35 to 44 underwent ophthalmological examination from 2007 to 2012. Amblyopia was defined as impaired visual acuity in the absence of any organic pathology capable of explaining the condition, and in the presence of a known risk factor for amblyopia.

RESULTS

Amblyopia, when defined as a visual acuity less than or equal to 0.63, was present in 182 participants (5.6%, 95% confidence interval [CI] 4.9-6.5%), 120 of whom had a visual acuity less than or equal to 0.5 (3.7%, 95% CI 3.3-5.2%). A narrower definition of amblyopia requiring, in addition, an interocular difference in acuity of at least two lines yielded slightly lower prevalence figures: 5.0% (95% CI 4.2-5.8%) and 3.7% (95% CI 3.1-4.4%), respectively. The causes of amblyopia (visual acuity ≤ 0.63) were anisometropia (different refractive strengths of the two eyes) in 49% of participants, strabismus (a squint) in 23%, both of these factors in 17%, and visual deprivation in 2%. 3 patients (2%) had relative amblyopia due to a traumatic cataract sustained in early childhood. 7% of the participants with amblyopia had binocular amblyopia.

CONCLUSION

This study yielded a prevalence figure of 5.6% for amblyopia in Germany-a higher figure than in other, comparable population-based studies, which have generally yielded figures of ca. 3% for visual acuity ≤ 0.63. The distribution of the causes of amblyopia is similar across studies.

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

AIM

To present and evaluate a new screening protocol for amblyopia in preschool children.

METHODS

Zagreb Amblyopia Preschool Screening (ZAPS) study protocol performed screening for amblyopia by near and distance visual acuity (VA) testing of 15 648 children aged 48-54 months attending kindergartens in the City of Zagreb County between September 2011 and June 2014 using Lea Symbols in lines test. If VA in either eye was >0.1 logMAR, the child was re-tested, if failed at re-test, the child was referred to comprehensive eye examination at the Eye Clinic.

RESULTS

78.04% of children passed the screening test. Estimated prevalence of amblyopia was 8.08%. Testability, sensitivity, and specificity of the ZAPS study protocol were 99.19%, 100.00%, and 96.68% respectively.

CONCLUSION

The ZAPS study used the most discriminative VA test with optotypes in line as they do not underestimate amblyopia. The estimated prevalence of amblyopia was considerably higher than reported elsewhere. To the best of our knowledge, the ZAPS study protocol reached the highest sensitivity and specificity when evaluating diagnostic accuracy of VA tests for screening. The pass level defined at ≤0.1 logMAR for 4-year-old children, using Lea Symbols in lines missed no amblyopia cases, advocating that both near and distance VA testing should be performed when screening for amblyopia.

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.

Whole-population vision screening in children aged 4-5 years to detect amblyopia

Amblyopia is a neurodevelopmental disorder that affects at least 2% of most populations and can lead to permanently reduced vision if not detected and treated within a specific period in childhood. Whole-population screening of children younger than 5 years is applied in many countries. The substantial diversity in existing programmes reflects their heterogeneous implementation in the absence of the complete evidence base that is now a pre-requisite for instituting screening. The functional importance of amblyopia at an individual level is unclear as data are scarce, but in view of the high prevalence the population-level effect might be notable. Screening of all children aged 4-5 years (eg, at school entry) confers most benefit and addresses inequity in access to timely treatment. Screening at younger ages is associated with increased risk of false-positive results, and at older ages with poor outcomes for children with moderate to severe amblyopia. We suggest that the real-life adverse effects of amblyopia should be characterised and screening and diagnosis should be standardised.

Amblyopia screening in Bulgaria

PURPOSE

To determine the prevalence of amblyopia and the average age at first ophthalmological examination of school-aged children from northwestern Bulgaria.

METHODS

Visual acuity testing, stereopsis, orthoptics, ocular motility, non-cycloplegic refraction, direct ophthalmoscopy, and external ocular inspection were performed. Cycloplegic refraction and indirect ophthalmoscopy were done as necessary. A total of 2,054 children (1,020 girls and 1,034 boys) were divided into three age groups: 6 to 8 years (803 children), 8 to 10 years (719 children), and 10 to 12 years (530 children).

RESULTS

A total of 1,861 children (90.6%) received their first examination: 754 (93.9%) aged 6 to 8 years, 638 (88.7%) aged 8 to 10 years, and 469 (88.2%) aged 10 to 12 years. Amblyopia was detected in 88 children (4.3%): 42 (5.2%) aged 6 to 8 years, 27 (3.8%) aged 8 to 10 years, and 19 (3.6%) aged 10 to 12 years. The first group had higher prevalence compared to countries with well-developed screening programs. Refractive errors were detected in 403 children (19.7%): 125 (15.6%) aged 6 to 8 years, 146 (20.3%) aged 8 to 10 years, and 132 (24.8%) aged 10 to 12 years. The estimated prevalence increases with age. Strabismus was detected in 24 children (1.2%): 8 (1.0%) aged 6 to 8 years, 7 (1.0%) aged 8 to 10 years, and 9 (1.7%) aged 10 to 12 years.

CONCLUSIONS

The lack of screening programs in Bulgaria is the main reason for late diagnosis of amblyopia. The "Do Good "project provided eye examination of school-aged children aged 6 to 12 years, when amblyopia is curable. This model could be used in establishing a Bulgarian national screening program.

Amblyopia treatment strategies and new drug therapies

Amblyopia is a unilateral or bilateral reduction of visual acuity secondary to abnormal visual experience during early childhood. It is one of the most common causes of vision loss and monocular blindness and is commonly associated with strabismus, anisometropia, and visual deprivation (in particular congenital cataract and ptosis). It is clinically defined as a two-line difference of best-corrected visual acuity between the eyes. The purpose of this study was to understand the neural mechanisms of amblyopia and summarize the current therapeutic strategies. In particular, the authors focused on the concept of brain plasticity and its implication for new treatment strategies for children and adults with amblyopia.