A systematic review of Amblyopia prevalence among the children of the world

Occlusion Outcomes in Unilateral Amblyopia Types: A Longitudinal and Interventional Study in Children from the Marrakech-Safi Region

Objective

To investigate if the type of unilateral amblyopia can impact the improvement of visual acuity in amblyopic eyes during a longitudinal interventional study involving standard occlusion therapy in children.

Methods

A longitudinal and interventional study of 91 children, aged 3-9 years (6.12 ± 1.879) with amblyopia was undertaken. Amblyopia was unilateral and caused by either strabismus, anisometropia, or both. Amblyopia was divided into three levels of severity mild, moderate, and severe. Children underwent amblyopia treatment with standard occlusion therapy and were followed monthly, for eight visits.

Results

A significant improvement in visual acuity was observed in all assessment visits across the three types of amblyopia, with a mean improvement of (0.30 ± 0.184) LogMAR. Specifically, anisometropic amblyopia with (0.28 ± 0.18) LogMAR, strabismic amblyopia (0.31 ± 0.18) LogMAR, and mixed amblyopia (0.31 ± 0.18) LogMAR. No significant differences were found between the improvement in visual acuity during the eight control visits and the types of amblyopia (r = 0.174, p = 0.182). However, a significant correlation was observed within all groups in the mean improvement in visual acuity and the severity level (r = 0.712, p = 0.034).

Conclusion

Amblyopia types do not appear to significantly affect the improvement in visual acuity; however, the initial severity of amblyopia may be a key factor influencing the degree of visual recovery achieved with occlusion therapy.

Rehabilitation of amblyopia using a digital platform for visual training combined with patching in children: a prospective study

PURPOSE

To assess the possible benefits of the use of perceptual learning and dichoptic therapy combined with patching in children with amblyopia over the use of only patching.

METHODS

Quasi-experimental multicentric study including 52 amblyopic children. Patients who improved their visual acuity (VA) by combining spectacles and patching were included in patching group (PG: 20 subjects), whereas those that did not improved with patching performed visual training (perceptual learning + dichoptic therapy) combined with patching, being assigned to the visual treatment group (VT: 32 subjects). Changes in VA, contrast sensitivity (CS), and stereopsis were monitored during a 6-month follow-up in each group.

RESULTS

Significant improvements in VA were found in both groups at 1 month (p < 0.01). The total improvement of VA was 0.18 ± 0.16 and 0.31 ± 0.35 logMAR in PG and VT groups, respectively (p = 0.317). The Wilcoxon effect size was slightly higher in VT (0.48 vs. 0.54) at 6 months. An enhancement in CS was observed in the amblyopic eye of the VT group for all spatial frequencies at 1 month (p < 0.001). Likewise, the binocular function score also increased significantly in VT group (p = 0.002). A prediction equation of VA improvement at 1 month in VT group was obtained by multiple linear regression analysis (p < 0.001, R2 = 0.747).

CONCLUSIONS

A combined treatment of visual training and patching is effective for obtaining a predictable improvement of VA, CS, and binocularity in patching-resistant amblyopic children.

Meridional Amblyopia and Spectacle Correction: A Prospective Interventional Study of Children Aged 4-11 Years

Background Amblyopia, often linked to high astigmatism in children, presents challenges in understanding the contributing factors and visual outcomes. Methods A total of 132 samples were included in this prospective pre- and post-interventional study using the purposive sampling technique. Descriptive statistics were applied for age, gender, uncorrected visual acuity, corrected visual acuity, type, and magnitude of astigmatism. A repeated measure ANOVA was used, and a paired t-test was also done for groups with corrected visual acuity in meridional amblyopia at two follow-ups spaced six months apart. Logistic regression was used to identify the association between astigmatism types and patients' recovery from amblyopia after intervention. Results The age of participants was 4-11 years with meridional amblyopia. Initial findings showed a mean uncorrected visual acuity of 0.73 LogMAR in the right eye (RE) and 0.71 LogMAR in the left eye (LE), improving significantly to 0.35 LogMAR post-intervention in both eyes. The calculated mean difference between the first correction and the first follow-up was 0.12 and 0.13 LogMAR, while it was 0.20 and 0.21 LogMAR in the RE and LE, respectively, at the second follow-up. Spherical refractive errors averaged +0.93 DS, with mean cylindrical refraction indicating predominant with-the-rule corneal astigmatism (-3.46 DS). We observed a significant improvement in visual acuity (p-value < 0.001) and an increase in the magnitude of cylindrical prescription (p-value < 0.001). However, astigmatism types are not associated with response to therapy. Conclusion The study concluded that early detection of meridional amblyopia and early intervention with spectacles significantly improve visual acuity.

Efficacy of Amblyopia Treatments in Children Up to Seven Years Old: A Systematic Review

Amblyopia is a neurodevelopmental disorder of the visual system that impairs the vision of millions of children worldwide. Amblyopia is best treated within the sensitive period of visual development when a child is up to seven years of age. Currently, the gold standard for early treatment of childhood amblyopia is patching, with new treatments emerging in recent years. We aim to evaluate the effectiveness of these newly developed treatments for amblyopia in children aged seven years and younger while comparing them to the current industry standard of patching. We searched online databases including PubMed, Google Scholar, and Cochrane Library for randomized controlled trials (RCTs), systematic reviews, meta-analyses, and narrative reviews relating to amblyopia treatment in children aged seven and younger. We only included articles and studies completed within the last five years and those written in the English language. After compiling a list of 297 articles, we removed duplicates, articles without an available full text, and those not relevant to our topic. Of the remaining 51 articles, we were left with 22 after reading abstracts and removing further irrelevant articles. We did a quality assessment on the remaining 22 articles and were left with 14 articles for our systematic review after removing eight low-quality articles. Of the 14 articles, we had eight RCTs, two systematic reviews, one comparative interventional study, and three narrative reviews. Seven of the articles contained data reinforcing the effectiveness of patching while comparing it to other treatment modalities. Three of the articles had data supporting spectacle correction, including a novel form called alternative flicker glass which delivers occlusion therapy via a spectacle frame with unique lenses, and ultimately deemed it at least as effective or more than patching. Data from three articles supported the use of surgery to successfully correct the angle of strabismus. Findings from five articles backed the use of pharmacologic therapy, specifically atropine when used alongside patching as a more effective alternative to patching solely. However, levodopa plus patching had no advantage over patching alone. Additionally, seven articles addressed the use of virtual reality (VR) and dichoptic therapy as prospective treatments for childhood amblyopia. VR therapy proved beneficial when used within one week after strabismus surgery. Dichoptic training was also effective in improving amblyopic-eye visual acuity when used on its own or in conjunction with spectacles. Furthermore, dichoptic movie therapy was found to be more effective than patching. Thus, we found multiple highly effective treatments for childhood amblyopia that are as effective or more than patching. Future studies should consider prescribing these treatments to larger cohorts while also performing a cost-benefit analysis for each treatment. In addition, more needs to be learned about the potential adverse side effects of these treatments, especially for pharmaceutical therapy.

Current Developments in the Management of Amblyopia with the Use of Perceptual Learning Techniques

Background and Objectives: Amblyopia is a neurodevelopmental disorder caused by interocular suppression of visual input, affecting visual acuity, stereopsis, contrast sensitivity, and other visual functions. Conventional treatment comprises occlusion of the sound eye. In recent years, novel therapies that deploy perceptual learning (PL) principles have been introduced. The purpose of this study is to assess the latest scientific data on this topic. Materials and Methods: For this purpose, we conducted a literature search for relevant studies published during the previous 4 years (2020-2023). Results: A plethora of visual perceptual learning protocols have been recently developed. Dichoptic video games, contrast rebalanced movies, and online perceptual training platforms are the main formats. Perceptual learning activates neuroplasticity, overcomes interocular suppression, and improves the visual impairments induced by amblyopia. Conclusions: This novel treatment is effective in both children and adults, as well as in patients non-responding to patching.

Effects of virtual reality on the treatment of amblyopia in children: A systematic review and meta-analysis

PROBLEM

Virtual reality technology has been used to treat amblyopia in children. However, it is unclear how virtual reality technology differs from conventional patching therapy in terms of effectiveness.

ELIGIBILITY CRITERIA

Eligible randomized controlled studies were retrieved from PubMed, Embase, Scopus, the Cochrane Library, and Web of Science through February 2023.

SAMPLE

Eight studies included 10 trials with 459 participants were included in the current meta-analysis. Two studies (Herbison et al., 2016; Huang et al., 2022) included two trials each. Thus, a total of ten trials were included in the current meta-analysis.

RESULTS

Overall, virtual reality technology treatment significantly improved visual acuity by 0.07 log MAR (95% confidence interval [CI], -0.11 to -0.02; P < 0.001; I2 = 94.4%) compared with traditional patching therapy. In addition, subgroup analyses also revealed that treatment with virtual reality technology was more effective when the child was younger than seven years old, or when the duration of the intervention was no more than twenty hours.

CONCLUSIONS

Virtual reality technology treatment showed significant effects in improving visual acuity in children who were seven years of age or younger with amblyopia.

IMPLICATIONS

Virtual reality technology treatment is effective in treating amblyopia in children. Virtual reality therapy is also entertaining and popular among children and can be applied to the treatment of amblyopia in children in the future.

The role of parental health beliefs in seeking an eye examination for their child

BACKGROUND

We aimed to explore the role of parental health beliefs in parent seeking of eye examinations for their children, using the Health Belief Model.

METHODS

In this quantitative correlational survey study, 100 parents who presented to Barzilai University Medical Center in July 2021 to perform an eye examination to their child completed a questionnaire.

RESULTS

Only 29.6% of the parents knew that a vision screening is performed in first grade, and 10% of the parents were unsure about where to find local eye care for their kids. Moreover, 19% of the parents indicated that they were concerned that their child would be prescribed glasses unnecessarily, and 10% believed that wearing glasses would weaken their child's eyes. Various parental health beliefs regarding children's eye examinations were found associated with parent seeking of eye examinations for their child. Thus, perceived susceptibility (r = 0.52, p < 0.01), perceived benefits (r = 0.39, p < 0.01), and perceived barriers (r=-0.31, p < 0.01) are associated with parent seeking of eye examinations for their child. Also, parents' level of knowledge was associated with seeking eye examinations for their child (r = 0.20, p < 0.01).

CONCLUSION

Parent perceptions of the child's susceptibility to vision problems and perceived barriers to seeking eye examinations predicted parents seeking of eye examinations for their child. Interventions aimed at increasing timely eye examinations among children should focus on raising parent awareness of vision problems in childhood, dispelling misconceptions, and providing parents with practical information regarding available services.

Ocular blood flow evaluation by laser speckle flowgraphy in pediatric patients with anisometropia

Purpose

To determine the differences and reproducibility of blood flow among hyperopic anisometropic, fellow, and control eyes.

Methods

We retrospectively studied 38 eyes of 19 patients with hyperopic anisometropia (8.2 ± 3.0 years of age) and 13 eyes of eight control patients (6.8 ± 1.9 years). We measured the optic nerve head (ONH) and choroidal circulation using laser speckle flowgraphy (LSFG) and analyzed the choroidal mean blur rate (MBR-choroid), MBR-A (mean of all values in ONH), MBR-V (vessel mean), MBR-T (tissue mean), and sample size (sample), which are thought to reflect the ONH area ratio, area ratio of the blood stream (ARBS). We then assessed the coefficient of variation (COV) and intraclass correlation coefficient (ICC) and compared the differences among amblyopic, fellow, and control eyes in MBR, sample, and ARBS.

Results

The ONH, MBR-A, MBR-T, and ARBS of amblyopic eyes were significantly higher than those of fellow eyes (P < 0.01, P < 0.05, and P < 0.05, respectively), and control eyes (MBR-A and ARBS, P < 0.05, for both comparisons). The sample-T (size of tissue component) in amblyopic eyes was significantly smaller than that in fellow and control eyes (P < 0.05). Blood flow in the choroid did not differ significantly between the eyes. The COVs of the MBR, sample, and ARBS were all ≤10%. All ICCs were ≥0.7. The COVs of pulse waveform parameter fluctuation, blowout score (BOS), blowout time (BOT), and resistivity index (RI) in the ONH and choroid were ≤10%.

Conclusion

The MBR value of the LSFG in children exhibited reproducibility. Thus, this method can be used in clinical studies. The MBR values of the ONH in amblyopic eyes were significantly high. It has been suggested that measuring ONH blood flow using LSFG could detect the anisometropic amblyopic eyes.

Amblyopia: A review of unmet needs, current treatment options, and emerging therapies

Amblyopia is a global public health issue with extensive, multifaceted impacts on vision and quality of life (QoL) for both patients and families. Geographical variation exists in the management of amblyopia, with traditional mainstay treatments, optical correction, and fellow eye occlusion most successful when implemented at an early age. In recent years, however, studies demonstrating meaningful improvements in older children and adults have challenged the concept of a complete loss of visual processing plasticity beyond the critical period of visual development, with growing evidence supporting the potential efficacy of emerging, more engaging, binocular therapies in both adults and children. Binocular approaches aim to restore deficits in amblyopia that extend beyond monocular visual acuity impairment, including binocular fusion and visuomotor skills. In view of this, incorporating outcome measures that evaluate the visual performance and functional ability of individuals with amblyopia will provide a clearer understanding of the effect of amblyopia on QoL and a more comprehensive evaluation of amblyopia therapies.

Applications and implications for extended reality to improve binocular vision and stereopsis

Extended reality (XR) devices, including virtual reality (VR), augmented reality (AR), and mixed reality (MR) devices, are immersive technologies that can swap or merge the natural environment with virtual content (e.g., videogames, movies, or other content). Although these devices are widely used for playing videogames and other applications, they have one distinct feature that makes them potentially very useful for the measurement and treatment of binocular vision anomalies-they can deliver different content to the two eyes simultaneously. Indeed, horizontally shifting the images in the two eyes (thereby creating binocular disparity) can provide the user with a compelling percept of depth through stereopsis. Because these devices are stereoscopic, they can also be used as high-tech synoptophores, in which the images to the two eyes differ in contrast, luminance, size, position, and content for measuring and treating binocular anomalies. The inclusion of eye tracking in VR adds an additional dimension to its utility in measuring and treating binocular vision anomalies, as well as other conditions. This paper describes the essential requirements for testing and treating binocular anomalies and reviews current studies in which XR devices have been used to measure and treat binocular vision anomalies.

Design and assessment of amblyopia, strabismus, and myopia treatment and vision training using virtual reality

Background

Virtual reality is a relatively new intervention that has the potential to be used in the treatment of eye and vision problems. This article reviews the use of virtual reality-related interventions in amblyopia, strabismus, and myopia research.

Methods

Sources covered in the review included 48 peer-reviewed research published between January 2000 and January 2023 from five electronic databases (ACM Digital Library, IEEE Xplore, PubMed, ScienceDirect and Web of Science). To prevent any missing relevant articles, the keywords, and terms used in the search included "VR", "virtual reality", "amblyopia", "strabismus," and "myopia". Quality assessment and data extraction were performed independently by two authors to form a narrative synthesis to summarize findings from the included research.

Results

Total number of 48 references were reviewed. There were 31 studies published on amblyopia, 18 on strabismus, and 6 on myopia, with 7 studies overlapping amblyopia and strabismus. In terms of technology, smartphone-based virtual reality headset viewers were utilized more often in amblyopia research, but commercial standalone virtual reality headsets were used more frequently in myopia and strabismus-related research. The software and virtual environment were mostly developed based on vision therapy and dichoptic training paradigms.

Conclusion

It has been suggested that virtual reality technology offers a potentially effective tool for amblyopia, strabismus, and myopia studies. Nonetheless, a variety of factors, especially the virtual environment and systems employed in the data presented, must be explored before determining whether virtual reality can be effectively applied in clinical settings. This review is significant as the technology in virtual reality software and application design features have been investigated and considered for future reference.

The Impact of Early Photoscreening on Medium-term Visual Acuity: A Population-Based Study

PURPOSE

To analyze the outcomes of an early ophthalmological intervention in children included in the pilot project of the "Rastreio de Saúde Visual Infantil" (RSVI) visual screening program in Portugal.

METHODS

This was a retrospective analysis of the medical records of all children included in the RSVI from April 1, 2016 to December 31, 2016, and who were referred to an ophthalmology appointment. Data of refractive errors, anisometropia, amblyopia, instituted treatments, and visual acuity at the end of the ophthalmological intervention were collected.

RESULTS

Two hundred sixty-seven (18.2%) 2-year-old children from the Centro Hospitalar Universitário do Porto reference area had a positive screening result and were subsequently referred to an ophthalmology appointment. Glasses were prescribed to 31.1% of the patients who attended. Presumed amblyopia was diagnosed in 2.5% and occlusion was prescribed. At the end of a median follow-up of 3 years, of those who wore glasses without occlusion, 94.3% had a visual acuity of 20/25 or better in both eyes with an asymmetry of two lines or less between eyes. Of the 4 children who wore glasses with occlusion, 3 of them had a visual acuity of 20/25 or better in both eyes with an asymmetry of two lines or less between eyes.

CONCLUSIONS

This study demonstrates the effectiveness of an early intervention in the prevention and treatment of amblyopia, because after a median follow-up of 3 years after treatment none of the referred children met criteria for amblyopia and 94.3% of the referred children who had an intervention had a normal visual acuity. [J Pediatr Ophthalmol Strabismus. 20XX;X(X):XX-XX.].

Abnormal effective connectivity in visual cortices underlies stereopsis defects in amblyopia

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Abnormal effective connectivity inherent stereopsis defects in amblyopia was studied.

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A weakened connection from V2v to LO2 relates to stereopsis defects in amblyopia.

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Higher-order visual cortices may serve as key nodes to the stereopsis defects.

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An independent longitudinal dataset was used to validate the obtained results.

The neural basis underlying stereopsis defects in patients with amblyopia remains unclear, which hinders the development of clinical therapy. This study aimed to investigate visual network abnormalities in patients with amblyopia and their associations with stereopsis function. Spectral dynamic causal modeling methods were employed for resting-state functional magnetic resonance imaging data to investigate the effective connectivity (EC) among 14 predefined regions of interest in the dorsal and ventral visual pathways. We adopted two independent datasets, including a cross-sectional and a longitudinal dataset. In the cross-sectional dataset, we compared group differences in EC between 31 patients with amblyopia (mean age: 26.39 years old) and 31 healthy controls (mean age: 25.71 years old) and investigated the association between EC and stereoacuity. In addition, we explored EC changes after perceptual learning in a novel longitudinal dataset including 9 patients with amblyopia (mean age: 15.78 years old). We found consistent evidence from the two datasets indicating that the aberrant EC from V2v to LO2 is crucial for the stereoscopic deficits in the patients with amblyopia: it was weaker in the patients than in the controls, showed a positive linear relationship with the stereoscopic function, and increased after perceptual learning in the patients. In addition, higher-level dorsal (V3d, V3A, and V3B) and ventral areas (LO1 and LO2) were important nodes in the network of abnormal ECs associated with stereoscopic deficits in the patients with amblyopia. Our research provides insights into the neural mechanism underlying stereopsis deficits in patients with amblyopia and provides candidate targets for focused stimulus interventions to enhance the efficacy of clinical treatment for the improvement of stereopsis deficiency.

Prevalence of myopia in 3-14-year-old Chinese children: a school-based cross-sectional study in Chengdu

Background

The prevalence of myopia among children in Chengdu is unknown. The aim of this study was to determine the prevalence of myopia in 3- to 14-year-old Chinese children in Chengdu.

Methods

This study was a school-based cross-sectional study in children aged 3–14 years. Visual acuity (VA), spherical equivalent error (SER) with noncycloplegic autorefraction, axial length (AL) and corneal radius (CR) were measured.

Results

A total of 19,455 children were recruited for this study. The prevalence of myopia was 38.1 %; the prevalence of low myopia was 26.6 %, that of moderate myopia was 9.8 %, and that of high myopia was 1.7 %. The prevalence of myopia and SER increased with age from 6 years old. The prevalence of myopia was higher, and the SER indicated more severe myopia in the girls than in the boys (40.1 % vs. 36.2 %, χ² = 30.67, d_f = 1, P < 0.001; -0.93 D ± 1.75 D vs. -0.84 D ± 1.74 D, t = 3.613, d_f=19,453, P < 0.001). The girls had a higher prevalence of myopia and myopic SER than did the boys aged 9 years and older (P < 0.05). Among the myopic children, the rates of uncorrected, undercorrected and fully corrected myopia were 54.8 %, 31.1 and 14.1 %, respectively. AL and AL/CR increased with age from 6 years old, but CR remained stable after 4 years old. The AL was longer, and the CR was flatter in the boys than in the girls aged 3 to 14 years old (P < 0.05).

Conclusions

The prevalence of myopia, AL and AL/CR increased, and the SER became more myopic with age from 6 years old. The girls had a higher prevalence of myopia and myopic SER than did the boys, but the boys had a longer AL, flatter CR and higher AL/CR ratio than did the girls. The rate of uncorrected myopia was very high in the myopic children. More actions need to be taken to decrease the prevalence of myopia, especially uncorrected myopia in children.