Original papers: Prevalence of amblyogenic diseases in a preschool population sample of Valladolid, Spain

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.

Instrument-based screening for amblyopia risk factors in a primary care setting in children aged 18 to 30 months

Amblyopia is the leading cause of vision impairment in children, and its early detection can avoid irreversible consequences for a child's visual ability. In this prospective study, to detect amblyopia risk factors, we examined patients aged 18 to 30 months in primary care settings. Patients were referred to an ophthalmologist for confirmation. The main aims were to detect amblyogenic risk factors and to assess the usefulness of a photoscreener in such settings. Out of 453 patients, 42 (9.3%) presented visual alterations according to the photoscreener, with astigmatism being the most common. The instrument had good sensitivity (89%) and specificity (91%), with a positive predictive value of 76% and a negative predictive value of 96%. Overall, 38% of the patients required follow-up, and 47% needed glasses. The automated screening device allowed these children to be diagnosed at an early stage.Conclusions: The use of a photoscreener to screen 2-year-old children in primary care settings was helpful and accurate. What is Known: • Early detection of amblyopic risk factors is important to avoid vision defects. However, it is very difficult to measure visual acuity using visual charts in children younger than 4 years old. What is New: • Instrument-based screening in children aged 18 to 30 months allows excellent detection of early amblyopia risk factors in primary care settings.

Satisfaction with strabismus surgery based on the opinion of expert surgeons

PURPOSE

To assess the perception of strabismus surgeons in Spain regarding patient satisfaction after surgery, by analysing the types of strabismus with the most satisfied patients, as well as the causes of dissatisfaction.

METHODS

A survey was carried out among the members of the Spanish Strabology Society who were over 50 years of age, active in Spain, with more than 20 years of surgical experience, and whose main surgical activity was strabismus. The questionnaire consisted of 18 questions about the perception of patient satisfaction according to the type of strabismus, patient age, as well as the most frequent cause of dissatisfaction after surgery.

RESULTS

The questionnaires were completed by a total of 29 surgeons, with a mean of 31 years of surgical experience. The most frequent cause of perceived dissatisfaction was residual strabismus. No differences were found in the satisfaction index between children and adults. The surgery that was considered to produce greater satisfaction was endotropia, followed by decompensated 4th nerve palsy, and exotropia, while 3rd nerve palsy was the cause of the most dissatisfaction.

CONCLUSIONS

According to strabismus surgeons, endotropia is the most satisfactory surgery for the patient, followed by exotropia, vertical strabismus, and traumatic paralysis of the 4th cranial nerve.

Global prevalence of amblyopia and disease burden projections through 2040: a systematic review and meta-analysis

Purpose

Amblyopia is a leading cause of vision impairment among children and young adults. Individual studies showed significant variations in the prevalence of amblyopia in different regions and age groups. This study is to estimate the global prevalence of amblyopia by pooling its prevalence from the previous studies and to project the number of people affected through 2040.

Methods

We performed a systematic review and meta-analysis on the prevalence of amblyopia using data published before 20 October 2018. We estimated the prevalence rate of amblyopia and its 95% CI globally and by subgroups (eg, region and age). The prevalence data were applied to United Nations World Population Prospects to derive the projected number with amblyopia through 2040.

Results

A meta-analysis of 60 studies (1 859 327 subjects) showed that the pooled prevalence rate of amblyopia was 1.44% (95% CI 1.17% to 1.78%). Prevalences in Europe (2.90%) and North America (2.41%) were higher than in Asia (1.09%) and Africa (0.72%). The highest prevalence was found in subjects over 20 years old (3.29%). There was no difference in the prevalence between genders. We estimated 99.2 (95% CI 71.7 to 146.1) million people with amblyopia in 2019 worldwide, increasing to 175.2 (95% CI 81.3 to 307.8) million by 2030 and 221.9 (95% CI 83.7 to 429.2) million by 2040.

Conclusions

The amblyopia is becoming a significant vision problem worldwide. It is of great importance to design and implement amblyopia screening, treatment and related public health strategies.

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.

Validation of a school-based amblyopia screening protocol in a kindergarten population

PURPOSE

To validate a school-based amblyopia screening program model by comparing its outcomes to those of a state-of-the-art conventional ophthalmic clinic examination in a kindergarten population of children between the ages of 4 and 5 years.

METHODS

An amblyopia screening protocol, which consisted of visual acuity measurement using Lea charts, ocular alignment test, ocular motility assessment, and stereoacuity with TNO random-dot test, was performed at school in a pediatric 4- to 5-year-old population by qualified healthcare professionals. The outcomes were validated in a selected group by a conventional ophthalmologic examination performed in a fully equipped ophthalmologic center. The ophthalmologic evaluation was used to confirm whether or not children were correctly classified by the screening protocol. The sensitivity and specificity of the test model to detect amblyopia were established.

RESULTS

A total of 18,587 4- to 5-year-old children were subjected to the amblyopia screening program during the 2010-2011 school year. A population of 100 children were selected for the ophthalmologic validation screening. A sensitivity of 89.3%, specificity of 93.1%, positive predictive value of 83.3%, negative predictive value of 95.7%, positive likelihood ratio of 12.86, and negative likelihood ratio of 0.12 was obtained for the amblyopia screening validation model.

CONCLUSIONS

The amblyopia screening protocol model tested in this investigation shows high sensitivity and specificity in detecting high-risk cases of amblyopia compared to the standard ophthalmologic examination. This screening program may be highly relevant for amblyopia screening at schools.

Screening for amblyogenic factors in preschool children with the retinomax hand-held refractor: do positive children have amblyopia and is treatment efficacious?

PURPOSE

To determine the visual acuity (VA) in a group of preschool children who were true positives for refractive screening (positive group) in order to compare it with the VA of a sample of children without any refractive anomaly (control group); also, to investigate if true-positive treated children can achieve the VA of the control group within what delay.

METHODS

Fifty seven children without any refractive anomaly were tested with the VA child chart if the Nidek SCP 670 projector; 47 children presenting with the refractive anomalies were tested with the same chart. A Kruskal Wallis exact test for singly ordered tables were used to compare VA between those groups and a non-parametric Wilcoxon test for paired samples was used to compare pre- and post-treatment VA in 27 children of the positive group. The mean time necessary to achieve the post-treatment VA was calculated.

RESULTS

Median VA: 20/20 in the control group, 20/33 in the positive group. The VA difference between the two pre- and post-treatment VA are highly significant. Among the 27 treated children, pre-treatment median VA was 20/50, post-treatment 20/20. The differences between the pre- and post-treatment VA was 9 months.

CONCLUSION

The positive group had a significantly lower VA than the control group. In the treated group, treatment initiated at a mean age of 4 years resulted in an increase in VA to that of the control group after an average time of 9 months, encouraging early screening and treatment before VA is measureable in order to shorten this delay.