Randomised controlled trial of treatment of unilateral visual impairment detected at preschool vision screening

A population-level post-screening treatment cost framework to help inform vision screening choices for children under the age of seven

PURPOSE/BACKGROUND

Visual acuity (VA) screening in children primarily detects low VA and amblyopia between 3 and 6 years of age. Photoscreening is a low-cost, lower-expertise alternative which can be carried out on younger children and looks instead for refractive amblyopia risk factors so that early glasses may prevent or mitigate the conditions. The long-term benefits and costs of providing many children with glasses in an attempt to avoid development of amblyopia for some of them needs clarification. This paper presents a framework for modeling potential post-referral costs of different screening models once referred children reach specialist services.

METHODS

The EUSCREEN Screening Cost-Effectiveness Model was used together with published literature to estimate referral rates and case mix of referrals from different screening modalities (photoscreening and VA screening at 2, 3-4 years and 4-5 years). UK 2019-20 published National Health Service (NHS) costings were used across all scenarios to model the comparative post-referral costs to the point of discharge from specialist services. Potential costs were compared between a) orthoptist, b) state funded ophthalmologist and c) private ophthalmologist care.

RESULTS

Earlier VA screening and photoscreening yield higher numbers of referrals because of lower sensitivity and specificity for disease, and a different case mix, compared to later VA screening. Photoscreening referrals are a mixture of reduced VA caused by amblyopia and refractive error, and children with amblyopia risk factors, most of which are treated with glasses. Costs relate mainly to the secondary care providers and the number of visits per child. Treatment by an ophthalmologist of a referral at 2 years of age can be more than x10 more expensive than an orthoptist service receiving referrals at 5 years, but outcomes can still be good from referrals aged 5.

CONCLUSIONS

All children should be screened for amblyopia and low vision before the age of 6. Very early detection of amblyopia refractive risk factors may prevent or mitigate amblyopia for some affected children, but population-level outcomes from a single high-quality VA screening at 4-5 years can also be very good. Total patient-journey costs incurred by earlier detection and treatment are much higher than if screening is carried out later because younger children need more professional input before discharge, so early screening is less cost-effective in the long term. Population coverage, local healthcare models, local case-mix, public health awareness, training, data monitoring and audit are critical factors to consider when planning, evaluating, or changing any screening programme.

Contour integration deficits at high spatial frequencies in children treated for anisometropic amblyopia

Purpose

This study was conducted to reexamine the question of whether children treated for anisometropic amblyopia have contour integration deficits. To do so, we used psychophysical methods that require global contour processing while minimizing the influence of low-level deficits: visibility, shape perception, and positional uncertainty.

Methods

Thirteen children with anisometropic amblyopia (age: 10.1 ± 1.8 years) and thirteen visually normal children (age: 10.8 ± 2.0 years) participated in this study. The stimuli were closed figures made up of Gabor patches either in noise or on a blank field. The contrast thresholds to detect a circular contour on a blank field, as well as the thresholds of aspect ratio and contour element number to discriminate a circular or elliptical contour in noise, were measured at Gabor spatial frequencies of 1.5, 3, and 6 cpd for amblyopic eyes (AEs), fellow eyes (FEs), and normal control eyes. Visual acuities and contrast sensitivity functions for AEs and FEs and the Randot stereoacuity were measured before testing.

Results

The AEs showed contrast deficits and degraded shape perception compared to the FEs at higher spatial frequencies (6 cpd). When the influence of abnormal contrast sensitivity and shape perception were minimized, the AEs showed contour integration deficits at spatial frequencies 3 and 6 cpd. These deficits were not related to basic losses in contrast sensitivity and acuity, stereoacuity, and visual crowding. Besides, no significant difference was found between the fellow eyes of the amblyopic children and the normal control eyes in the performance of contour integration.

Conclusion

After eliminating or compensating for the low-level deficits, children treated for anisometropic amblyopia still show contour integration deficits, primarily at higher spatial frequencies, which might reflect the deficits in global processing caused by amblyopia. Contour integration deficits are likely independent of spatial vision deficits. Refractive correction and/or occlusion therapies may not be sufficient to fully restore contour integration deficits, which indicates the need for the development of clinical treatments to recover these deficits.

Automated vision screening of children using a mobile graphic device

BACKGROUND/OBJECTIVE

Can measuring interocular brightness disparity, acuity, and colour vision classify children with amblyopia?

SUBJECTS/METHODS

Two hundred eight subjects (3-14 years) were recruited for a prospective, observational protocol to measure interocular brightness disparity, uniocular acuities with and without a pinhole, and colour vision using an iPad. Subjects looked through polarizing filters and chose the brighter of two spaceships to measure interocular brightness disparity. The differential brightness of image pairs was varied through a staircase algorithm until equal brightness was perceived. Acuities and colour vision were tested with tumbling Es and AO-HRR colour plates, respectively. Unilateral amblyopia was later confirmed in two subjects.

RESULTS

Binocular brightness balance on the iPad detected amblyopes with 100% sensitivity and specificity. Using 20/30 as cutoff for normal acuity, 1 of the amblyopes was detected, and non-amblyopes were excluded by visual acuity pinhole testing. The mean difference between iPad and E-Chart visual acuities with pinhole was 0.02 logMAR with limits of agreement from -0.08 to +0.11 logMAR. iPad and printed plates Colour vision testing produced identical results. Testing times were brief and exit pleasure responses were positive. Mean and range testing times for Brightness Sense, Colour vision, and Visual Acuity were 32.7 s (range = 12-63 s), 52.8 min (range = 17-95 s), and 88.75 s (range = 41-188 s), respectively.

CONCLUSIONS

Interocular brightness disparity, acuity, and colour vision can be measured in children as young as 3 years old solely through playing a game on a mobile device. Interocular brightness disparity is a sensitive and specific method to detect unilateral amblyopia.

Developmental spontaneous activity promotes formation of sensory domains, frequency tuning and proper gain in central auditory circuits

Neurons that process sensory information exhibit bursts of electrical activity during development, providing early training to circuits that will later encode similar features of the external world. In the mammalian auditory system, this intrinsically generated activity emerges from the cochlea prior to hearing onset, but its role in maturation of auditory circuitry remains poorly understood. We show that selective suppression of cochlear supporting cell spontaneous activity disrupts patterned burst firing of central auditory neurons without affecting cell survival or acoustic thresholds. However, neurons in the inferior colliculus of these mice exhibit enhanced acoustic sensitivity and broader frequency tuning, resulting in wider isofrequency laminae. Despite this enhanced neural responsiveness, total tone-responsive regions in the auditory cortex are substantially smaller. Thus, disruption of pre-hearing cochlear activity causes profound changes in neural encoding of sound, with important implications for restoration of hearing in individuals who experience reduced activity during this critical developmental period.

Management of amblyopia in pediatric patients: Current insights

Amblyopia is a cause of significant ocular morbidity in pediatric population and may lead to visual impairment in future life. It is caused due to formed visual deprivation or abnormal binocular interactions. Several risk factors in pediatric age group may lead to this disease. Author groups have tried managing different types of amblyopia, like anisometropic amblyopia, strabismic amblyopia and combined mechanism amblyopia, with optical correction, occlusion therapy, penalization, binocular therapy and surgery. We review historical and current management strategies of different types of amblyopia affecting children and outcomes in terms of visual acuity, binocularity and ocular deviation, highlighting evidence from recent studies. Literature searches were performed through Pubmed. Risk factors for amblyopia need to be identified in pediatric population as early in life as possible and managed accordingly, as visual outcomes in amblyopia are best if treated at the earliest. Although, monocular therapies like occlusion or penalization have been shown to be quite beneficial over the years, newer concepts related to binocular vision therapy are still evolving.

CHARGE Syndrome Associated with Ocular Abnormalities: A Case Report with Treatment of Amblyopia and Refractive Correction

CHARGE syndrome is a rare genetic disorder associated with many ocular anomalies including amblyopia, strabismus and high refractive errors. It has been found that the visual acuity of patients with CHARGE syndrome is typically lower than 20/60. After reviewing the literature, there has been a lack of detailed information about the assessments of visual function. Thus, this case report illustrates the strategy plan to treat amblyopia and refractive correction for a young girl with CHARGE syndrome.

Amblyopia treatment: an evidence‐based approach to maximising treatment outcome

The basis of treatment for amblyopia (poor vision due to abnormal visual experience early in life) for 250 years has been patching of the unaffected eye for extended times to ensure a period of use of the affected eye. Over the last decade randomised controlled treatment trials have provided some evidence on how to tailor amblyopia therapy more precisely to achieve the best visual outcome with the least negative impact on the patient and the family. This review highlights the expansion of knowledge regarding treatment for amblyopia and aims to provide optometrists with a summary of research evidence to enable them to better treat amblyopia. Treatment for amblyopia is effective, as it reduces overall prevalence and severity of visual loss in this population. Correction of refractive error alone significantly improves visual acuity, sometimes to the point where further amblyopia treatment is not required. Atropine penalisation and patch occlusion are effective in treating amblyopia. Lesser amounts of occlusion or penalisation have been found to be just as effective as greater amounts. Recent evidence has highlighted that occlusion or penalisation in amblyopia treatment can create negative changes in behaviour in children and impact on family life. These complications should be considered when prescribing treatment because they can negatively affect compliance. Studies investigating the maximum age at which treatment of amblyopia can still be effective and the importance of near activities during occlusion are ongoing.

Amblyopia: prevalence, natural history, functional effects and treatment

Amblyopia, defined as poor vision due to abnormal visual experience early in life, affects approximately three per cent of the population and carries a projected lifetime risk of visual loss of at least 1.2 per cent. The presence of amblyopia or its risk factors, mainly strabismus or refractive error, have been primary conditions targeted in childhood vision screenings. Continued support for such screenings requires evidence-based understanding of the prevalence and natural history of amblyopia and its predisposing conditions, and proof that treatment is effective in the long term with minimal negative impact on the patient and family. This review summarises recent research relevant to the clinical understanding of amblyopia, including prevalence data, risk factors, the functional impact of amblyopia and optimum treatment regimes and their justification from a vision and life skills perspective. Collectively, these studies indicate that treatment for amblyopia is effective in reducing the overall prevalence and severity of visual loss from amblyopia. Correction of refractive error alone has been shown to significantly reduce amblyopia and less frequent occlusion can be just as effective as more extensive occlusion. Occlusion or penalisation in amblyopia treatment can create negative changes in behaviour in children and impact on family life, and these factors should be considered in prescribing treatment, particularly because of their influence on compliance. Ongoing treatment trials are being undertaken to determine both the maximum age at which treatment of amblyopia can still be effective and the importance of near activities during occlusion. This review highlights the expansion of current knowledge regarding amblyopia and its treatment to help clinicians provide the best level of care for their amblyopic patients that current knowledge allows.

Amblyopia Outcomes Through Clinical Trials and Practice Measurement: Room for Improvement: The LXXVII Edward Jackson Memorial Lecture

PURPOSE

To describe amblyopia prevalence and outcomes using results from randomized studies and a clinical registry.

DESIGN

Review of published studies, analysis of data in Intelligent Research in Sight (IRIS) Registry from 2013 to 2019, personal perspective.

METHODS

Literature review, analysis of IRIS Registry data and IRIS-50, a visual acuity quality measure.

RESULTS

Clinical trials have reduced the treatment burden of amblyopia by reducing hours of patching and frequency of atropine eye drops with clinical success of about 83%. There is no appreciable age effect if treatment is started before 5 years of age, outcomes are stable to at least 15 years of age, and treatment can be somewhat effective until 12 years of age. The IRIS Registry identified 1,760,066 individuals with amblyopia for a prevalence of 2.47%. Refractive error alone accounted for 68.9% of childhood cases. Mean amblyopic eye visual acuity improved 1.8 lines for children 3-6 years of age and 0.8 lines for 7-12 years, but mean residual amblyopia was more than 2 lines. Among 18,841 children aged 3-7 years eligible for IRIS-50, 77.3% were successful. The odds ratios for success were significantly lower for African-American (0.67; 95% confidence interval [CI] = 0.58 to 0.78) and Hispanic or Latino (0.84; 95% CI = 0.75 to 0.94) children compared with white children.

CONCLUSIONS

Clinical trials provided evidence of a beneficial effect from several treatments, with substantially reduced doses than previously recommended. Registry data from clinical practice found residual visual acuity impairment among all ages and races, especially among minorities.

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.

Feasibility of a school-based vision screening program to detect undiagnosed visual problems in kindergarten children in Ontario

BACKGROUND

Visual problems can negatively affect visual development and learning but often go undetected. We assessed the feasibility of scaling up a school-based screening program to identify and treat kindergarten children with visual problems.

METHODS

We conducted a prospective cohort study offering vision screening to junior (JK) and senior kindergarten (SK) children attending 43 schools in 15 Ontario communities. Screening comprised photoscreeners and tests of visual acuity, stereoacuity and eye alignment. Children who failed any test were referred for a comprehensive eye examination, with treatment as needed (e.g., glasses).

RESULTS

Using a passive consent model, 89% of children were screened compared with 62% using an active consent model (p < 0.001). Referral rates to an optometrist varied across schools (mean referral rate for children in JK 53%, range 25%-83%; mean referral rate for children in SK 34%, range 12%-61%). Among 4811 children who were screened, a visual problem was detected in 516 (10.7%), including 164 (3.4%) with amblyopia and 324 (6.7%) with clinically significant refractive errors. For 347 (67.2%) of the children with a visual problem, this was their first eye examination. Rescreening in Year 2 did not lead to detection of additional problems among children who passed screening in Year 1. Regardless of location (child's school or optometrist's office), 1563 (68.9%) of children attended the follow-up optometry examination. Most of the children who were surveyed (291 of 322, 90.4%) indicated that they enjoyed vision screening.

INTERPRETATION

Many children in Ontario with a visual problem were not being identified by the status quo in 2015-2017. We found that in-school vision screening with follow-up eye examinations is an effective strategy for identifying at-risk children and placing them in eye care before grade 1.

Occlusion for stimulus deprivation amblyopia

BACKGROUND

Stimulus deprivation amblyopia (SDA) develops due to an obstruction to the passage of light secondary to a condition such as cataract. The obstruction prevents formation of a clear image on the retina. SDA can be resistant to treatment, leading to poor visual prognosis. SDA probably constitutes less than 3% of all amblyopia cases, although precise estimates of prevalence are unknown. In high-income countries, most people present under the age of one year; in low- to middle-income countries, people are likely to be older at the time of presentation. The mainstay of treatment is correction of the obstruction (e.g., removal of the cataract) and then occlusion of the better-seeing eye, but regimens vary, can be difficult to execute, and traditionally are believed to lead to disappointing results.

OBJECTIVES

To evaluate the effectiveness of occlusion therapy for SDA in an attempt to establish realistic treatment outcomes and to examine evidence of any dose-response effect and assess the effect of the duration, severity, and causative factor on the size and direction of the treatment effect.

SEARCH METHODS

We searched CENTRAL (2018, Issue 12), which contains the Cochrane Eyes and Vision Trials Register; Ovid MEDLINE; Embase.com; and five other databases. We used no date or language restrictions in the electronic searches. We last searched the databases on 12 December 2018.

SELECTION CRITERIA

We planned to include randomized controlled trials (RCTs) and controlled clinical trials of participants with unilateral SDA with visual acuity worse than 0.2 LogMAR or equivalent. We specified no restrictions for inclusion based upon age, gender, ethnicity, comorbidities, medication use, or the number of participants.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology.

MAIN RESULTS

We identified no trials that met the inclusion criteria specified in the protocol for this review.

AUTHORS' CONCLUSIONS

We found no evidence from RCTs or quasi-randomized trials on the effectiveness of any treatment for SDA. RCTs are needed in order to evaluate the safety and effectiveness of occlusion, duration of treatment, level of vision that can be realistically achieved, effects of age at onset and magnitude of visual defect, optimum occlusion regimen, and factors associated with satisfactory and unsatisfactory outcomes with the use of various interventions for SDA.

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.

'It's too late'. Is it really? Considerations for amblyopia treatment in older children

In recent years, media coverage has demonstrated instances in which families of children aged 7 and older, newly diagnosed with strabismic and/or anisometropic amblyopia through community eyecare services, were told it was 'too late' for their child to effectively respond to conventional amblyopia treatment (occlusion or atropine penalisation). Formal guidance pertaining to binocular vision anomalies from eyecare professional bodies does not specifically make reference to a child's age, beyond stating the importance of early diagnosis and treatment of strabismus/amblyopia. However, there have been many changes in the way we view the recovery period for amblyopia, and it is well demonstrated both within literature and clinical practice that conventional treatment can improve amblyopic eye visual acuity in children beyond the age of 7 years. The occurrence of these media described cases within the community eyecare sphere would suggest it is worthwhile revisiting the literature on the subject of amblyopia treatment in older children (aged 7+ years), to address misconceptions and place in the spotlight current considerations facing clinicians when treating newly diagnosed amblyopia within this age group. This perspective review provides an evidence-based update covering the various considerations associated with treatment of amblyopia in older children, along with recent amblyopia treatment advances that could have an impact on treatment prospects for this patient group. Considerations include the risks, benefits and efficacy of treating newly diagnosed amblyopia in older children, monitoring density of suppression to mitigate intractable diplopia risk, and recent findings regarding binocular treatments for amblyopia.

Atropine Penalization Versus Occlusion Therapies for Unilateral Amblyopia after the Critical Period of Visual Development: A Systematic Review

Introduction

Amblyopia therapy appears to be most effective in children under the age of 7 years, but results from randomized control trials (RCTs) have shown that occlusion therapy and/or atropine penalization therapy may improve visual acuity in an older age group. Which of these two therapies is the most effective with fewer adverse effects in an older age group has not yet been agreed upon.

Methods

We systematically searched the literature for RCTs that compared atropine penalization therapy and occlusion therapy in terms of their visual acuity outcomes and adverse events and performed a meta-analysis on the visual acuity data obtained. The adverse effects reported and their implications for clinical practice are discussed.

Results

Two RCTs were identified, with the authors of both concluding that there was no detectable difference between the two therapies for the age groups they studied. The mean difference between atropine penalization and occlusion therapies was calculated to be − 0.01 logMAR (95% confidence interval − 0.07 to 0.03 logMAR) in favor of occlusion therapy, and no statistical difference between the two groups was detected (P = 0.45). Neither study detected a marked difference in terms of reported adverse effects from the two interventions.

Conclusion

Based on the results of our meta-analysis we conclude that there is no difference in visual acuity outcomes between atropine penalization therapy and occlusion therapy after 17 to 24 weeks of treatment in children aged 7–12 years. Further evidence to determine the efficacy of amblyopia therapy for an older patient population is required before studies comparing atropine penalization and occlusion therapy in patients older than 12 years can be performed. Atropine penalization therapy may cause more frequent minor adverse effects, such as light sensitivity, but in the clinical setting this needs to be balanced with the potential practical benefits of twice-weekly eye drops versus daily occlusion.

Funding

The funding for this study was provided by the National Institute for Health Research (NIHR) and Health Education England (HEE).

Plain Language Summary

A plain language summary is available for this article.

Electronic supplementary material

The online version of this article (10.1007/s40123-018-0151-9) contains supplementary material, which is available to authorized users.

The functional impact of amblyopia

Amblyopia is the most common disorder managed in paediatric ophthalmic practice in industrialised countries. Reports on the impact of amblyopia on tasks relevant to the activities of children, or on skills pertinent to their education and quality of life, is leading to greater understanding of the functional disabilities associated with the condition. This review considers the extent to which amblyopia affects the ability to carry out everyday tasks, with particular attention to studies of motor skills and reading proficiency in children. Collectively, these studies show that amblyopia results in poorer outcomes on tests of skills required for proficiency in everyday tasks and which relate to childhood academic performance. However, the relative contributions that the documented vision anomalies inherent in amblyopia contribute to various functional disabilities is not fully determined. Recent reports have demonstrated improvement following treatment in standardised measures of fine motor skills involved in practical, everyday tasks. Including measurement of functional performance skills in amblyopia treatment trials is desirable to show treatment effect on crucial, real-world activities.

Effect of 4-Month Intermittent Atropine Penalization in Amblyopic Children for Whom Patch Therapy Had Failed

PURPOSE

To evaluate the effect of 4-month intermittent atropine penalization in children with amblyopia for whom patch therapy had failed and to analyze the factors associated with treatment success.

METHODS

This retrospective observational study included participants who visited the hospital between January 1, 2011, and December 31, 2015. Forty-one children with amblyopia for whom patch therapy had failed were included and their medical records were analyzed retrospectively. They were treated with 1% atropine eye drops in the sound eye twice per week for 4 months. Treatment success was defined as a best corrected visual acuity (BCVA) improvement of two lines in the amblyopic eye. Age, cause of amblyopia, pretreatment BCVA at the start of atropine penalization in the amblyopic eye, age at the start of eyeglass prescription, age at the start of patch therapy, duration, compliance with and total amount of patch therapy, type of refraction, type of strabismus, and cause of failure of patch therapy were analyzed and compared between two groups: the failure and success groups.

RESULTS

Twenty of 41 patients (48.8%) showed treatment success. The mean age was 5.59 ± 1.52 years and the mean BCVA of the amblyopic eye was 0.40 ± 0.20 logarithm of the minimum angle of resolution (logMAR). Younger age and poor pretreatment BCVA at the start of atropine penalization in the amblyopic eye were the factors associated with treatment success.

CONCLUSIONS

Intermittent atropine penalization for 4 months can improve BCVA in children with amblyopia for whom patch therapy has failed. Atropine penalization can be especially effective in younger children and those with poor BCVA at the start of atropine penalization in the amblyopic eye. [J Pediatr Ophthalmol Strabismus. 2017;54(6):375-380.].

Occlusion dose monitoring in amblyopia therapy: status, insights, and future directions

Occlusion therapy remains the mainstay treatment of amblyopia, but its outcome is not assured or universally excellent. Many factors are known to influence treatment outcome, among which compliance is foremost. The occlusion dose monitor (ODM) removes one variable from the treatment equation, because it records the occlusion actually received by-rather than prescribed for-the child. Improvement observed can thus be quantitatively related to the patching received. This review summarizes the insights the ODM has provided to date particularly in elucidating the dose-response relationship. We are entering the era of personalized ophthalmology in which treatments will be tailored to the needs of the individual child and facilitated by the use of wearable monitors.

Randomised controlled trial of video clips and interactive games to improve vision in children with amblyopia using the I-BiT system

Background

Traditional treatment of amblyopia involves either wearing a patch or atropine penalisation of the better eye. A new treatment is being developed on the basis of virtual reality technology allowing either DVD footage or computer games which present a common background to both eyes and the foreground, containing the imagery of interest, only to the amblyopic eye.

Methods

A randomised control trial was performed on patients with amblyopia aged 4–8 years with three arms. All three arms had dichoptic stimulation using shutter glass technology. One arm had DVD footage shown to the amblyopic eye and common background to both, the second used a modified shooter game, Nux, with sprite and targets presented to the amblyopic eye (and background to both) while the third arm had both background and foreground presented to both eyes (non-interactive binocular treatment (non-I-BiT) games).

Results

Seventy-five patients were randomised; 67 were residual amblyopes and 70 had an associated strabismus. The visual acuity improved in all three arms by approximately 0.07 logMAR in the amblyopic eye at 6 weeks. There was no difference between I-BiT DVD and non-I-BiT games compared with I-BiT games (stated primary outcome) in terms of gain in vision.

Conclusions

There was a modest vision improvement in all three arms. Treatment was well tolerated and safe. There was no difference between the three treatments in terms of primary stated outcomes but treatment duration was short and the high proportion of previously treated amblyopia and strabismic amblyopia disadvantaged dichoptic stimulation treatment.

Trial registration number

NCT01702727, results.

Amblyopia in children (aged 7 years or less)

INTRODUCTION

Amblyopia is reduced visual acuity not immediately correctable by glasses, in the absence of ocular pathology. It is commonly associated with squint (strabismus) or refractive errors resulting in different visual inputs to each eye during the sensitive period of visual development (aged <7-8 years). The cumulative incidence is estimated at 2% to 4% in children aged up to 7 years.

METHODS AND OUTCOMES

We conducted a systematic overview, aiming to answer the following clinical question: What are the effects of medical treatments for amblyopia in children aged 7 years or less? We searched: Medline, Embase, The Cochrane Library, and other important databases up to January 2014 (Clinical Evidence overviews are updated periodically; please check our website for the most up-to-date version of this overview).

RESULTS

At this update, searching of electronic databases retrieved 70 studies. After deduplication and removal of conference abstracts, 51 records were screened for inclusion in the overview. Appraisal of titles and abstracts led to the exclusion of 37 studies and the further review of 14 full publications. Of the 14 full articles evaluated, two systematic reviews were updated and three RCTs and two follow-up studies were added at this update. We performed a GRADE evaluation for nine PICO combinations.

CONCLUSIONS

In this systematic overview we categorised the efficacy for three interventions, based on information about the effectiveness and safety of glasses, occlusion, or penalisation with atropine.

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.

Prevalence of amblyopia in primary school children in Qassim province, Kingdom of Saudi Arabia

PURPOSE

To determine the prevalence and causes of amblyopia in primary school children in Qassim province, Kingdom of Saudi Arabia (KSA).

MATERIALS AND METHODS

In this cross sectional study, 5176 children, aged 6 to 13 years (mean - 9.53 ± 1.88 years) were evaluated. There were 2573 (49.71%) males and 2603 (50.29%) females. Distance visual acuity (V/A) was tested monocularly using a logMAR chart with and without correction. Cycloplegic refraction was performed in children with reduced vision. To determine the etiology of amblyopia, children were enrolled if there was a difference in V/A of two or more lines between eyes or an absolute reduction in acuity <20/30 in either eye, that could not be corrected by refraction. P ≤ 0.05 was considered statistically significant.

RESULTS

There 202 out of 5176 (3.90%) with ambylopia. There are 98 (1.88%) amblyopic females. There was no statistical difference in gender for amblyopes (P > 0.05). The prevalence of amblyopia was statistically significant higher in the older age group (10-13 year) compared to younger age group (6 to 9 years) (P < 0.05). Unilateral amblyopia (3.24%) was more frequent than bilateral amblyopia (0.66%). The most frequent causes of amblyopia were refractive error (94.56%), of which anisometropic amblyopia was present in 77.72%, isoametropic amblyopia in 16.84% and strabismus in 5.44%.

CONCLUSION

The prevalence of amblyopia in Qassim province, KSA, is 3.9% which is similar or higher than other published studies on amblyopia. Anisometropic refractive errors are the most common underlying cause for this population. We recommend implementation of visual screening programs for children with appropriate clinical and social settings for early detection and proper management of amblyopia.

Designing clinical trials for amblyopia

Randomized clinical trial (RCT) study design leads to one of the highest levels of evidence, and is a preferred study design over cohort studies, because randomization reduces bias and maximizes the chance that even unknown confounding factors will be balanced between treatment groups. Recent randomized clinical trials and observational studies in amblyopia can be taken together to formulate an evidence-based approach to amblyopia treatment, which is presented in this review. When designing future clinical studies of amblyopia treatment, issues such as regression to the mean, sample size and trial duration must be considered, since each may impact study results and conclusions.

An educational intervention to improve adherence to high-dosage patching regimen for amblyopia: a randomised controlled trial

BACKGROUND

Previous reports suggest that adherence to patching is a major issue in amblyopia treatment. We tested with an unmasked randomised controlled clinical trial whether an intense educational/motivational intervention improves adherence when a high-dose regime is prescribed.

METHODS

62 children with newly diagnosed amblyopia were randomly allocated into two treatment arms with and without educational/motivational intervention material. Both were prescribed patching 10 h/day, 6 days/week for a fixed period of 12 weeks. The intervention arm received an educational/motivational intervention before patching which included information booklets, video, a cartoon story book, sticker charts and a dedicated session with a researcher. The control arm received the usual clinical information. The primary outcome measure was adherence measured using electronic occlusion dose monitors where a success/failure binary outcome was used to account for participants who dropped out of the study defined as patching >4 h/day. Visual outcome, expressed as percentage visual deficit, was measured as secondary outcome.

RESULTS

The intervention increased adherence success rate from 45.2% in the control group to 80.6% in the intervention group (p=0.0027). However, visual outcome was not significantly better in the intervention group (p=0.190).

CONCLUSIONS

Our study shows that an intense educational/motivational intervention can improve adherence to patching to high prescribed doses although no significant improvement in visual outcome was observed. TRIALS REGISTRATION NUMBER: ISRCTN05346737 (International Standard Randomised Controlled Trial Number Register).

A double dissociation of the acuity and crowding limits to letter identification, and the promise of improved visual screening

Here, we systematically explore the size and spacing requirements for identifying a letter among other letters. We measure acuity for flanked and unflanked letters, centrally and peripherally, in normals and amblyopes. We find that acuity, overlap masking, and crowding each demand a minimum size or spacing for readable text. Just measuring flanked and unflanked acuity is enough for our proposed model to predict the observer's threshold size and spacing for letters at any eccentricity. We also find that amblyopia in adults retains the character of the childhood condition that caused it. Amblyopia is a developmental neural deficit that can occur as a result of either strabismus or anisometropia in childhood. Peripheral viewing during childhood due to strabismus results in amblyopia that is crowding limited, like peripheral vision. Optical blur of one eye during childhood due to anisometropia without strabismus results in amblyopia that is acuity limited, like blurred vision. Furthermore, we find that the spacing:acuity ratio of flanked and unflanked acuity can distinguish strabismic amblyopia from purely anisometropic amblyopia in nearly perfect agreement with lack of stereopsis. A scatter diagram of threshold spacing versus acuity, one point per patient, for several diagnostic groups, reveals the diagnostic power of flanked acuity testing. These results and two demonstrations indicate that the sensitivity of visual screening tests can be improved by using flankers that are more tightly spaced and letter like. Finally, in concert with Strappini, Pelli, Di Pace, and Martelli (submitted), we jointly report a double dissociation between acuity and crowding. Two clinical conditions-anisometropic amblyopia and apperceptive agnosia-each selectively impair either acuity A or the spacing:acuity ratio S/A, not both. Furthermore, when we specifically estimate crowding, we find a double dissociation between acuity and crowding. Models of human object recognition will need to accommodate this newly discovered independence of acuity and crowding.

Occlusion for stimulus deprivation amblyopia

BACKGROUND

Stimulus deprivation amblyopia (SDA) develops due to an obstruction to the passage of light secondary to a condition such as cataract. The obstruction prevents formation of a clear image on the retina. SDA can be resistant to treatment, leading to poor visual prognosis. SDA probably constitutes less than 3% of all amblyopia cases, although precise estimates of prevalence are unknown. In developed countries, most patients present under the age of one year; in less developed parts of the world patients are likely to be older at the time of presentation. The mainstay of treatment is removal of the cataract and then occlusion of the better-seeing eye, but regimens vary, can be difficult to execute, and traditionally are believed to lead to disappointing results.

OBJECTIVES

Our objective was to evaluate the effectiveness of occlusion therapy for SDA in an attempt to establish realistic treatment outcomes. Where data were available, we also planned to examine evidence of any dose response effect and to assess the effect of the duration, severity, and causative factor on the size and direction of the treatment effect.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 9), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to October 2013), EMBASE (January 1980 to October 2013), the Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to October 2013), PubMed (January 1946 to October 2013), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com ), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 28 October 2013.

SELECTION CRITERIA

We planned to include randomized and quasi-randomized controlled trials of participants with unilateral SDA with visual acuity worse than 0.2 LogMAR or equivalent. We did not specify any restrictions for inclusion based upon age, gender, ethnicity, co-morbidities, medication use, or the number of participants.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study abstracts identified by the electronic searches.

MAIN RESULTS

We did not identify any trials that met the inclusion criteria specified in the protocol for this review.

AUTHORS' CONCLUSIONS

We found no evidence on the effectiveness of any treatment for SDA. Future randomized controlled trials are needed in order to evaluate the safety and effectiveness of occlusion, duration of treatment, level of vision that can be realistically achieved, effects of age at onset and magnitude of visual defect, optimum occlusion regimen, and factors associated with satisfactory and unsatisfactory outcomes with the use of various interventions for SDA.

Two-year follow-up of a randomized trial of spectacles plus alternate-day patching to treat strabismic amblyopia

PURPOSE

  To compare spectacles plus alternate-day patching for 8 hr or more with spectacles plus patching for 8 hr or more 6 days weekly to treat strabismic amblyopia 1 year after a 1-year randomized trial.

METHODS

Forty children (mean age, 4.3 years) participated. Refractive correction was provided. The children were assigned to alternate-day patching for 8 hr or more or patching for 8 hr or more daily 6 days weekly. VA, binocular function, and refractive errors were measured after 2 years. The main outcome measure was the median VA change in the amblyopic eye after 2 years.

RESULTS

The median VA change in the amblyopic eye at the 2-year visit was significantly (p = 0.0453) greater with alternate-day patching (0.8 log unit) versus patching daily 6 days weekly (0.6 log unit). The final median VA in the amblyopic eyes was 0.0 logMAR in the alternate-day patching group and 0.1 logMAR in the daily patching group. Binocular function improved with both treatments. The median spherical equivalent (SE) refractive error increased in the fellow eyes (alternate-day patching, p < 0.0001; patching daily 6 days weekly, p = 0.0033); no change was found in the amblyopic eyes in either group.

CONCLUSIONS

The magnitude of the VA change 2 years after treatment with spectacles plus alternate-day patching for 8 hr or more was significantly greater than with spectacles plus daily patching for 8 hr or more 6 days weekly for strabismic amblyopia. However, the final median VA did not differ significantly between the two treatments.

The relationship between anisometropia and amblyopia

This review aims to disentangle cause and effect in the relationship between anisometropia and amblyopia. Specifically, we examine the literature for evidence to support different possible developmental sequences that could ultimately lead to the presentation of both conditions. The prevalence of anisometropia is around 20% for an inter-ocular difference of 0.5D or greater in spherical equivalent refraction, falling to 2-3%, for an inter-ocular difference of 3D or above. Anisometropia prevalence is relatively high in the weeks following birth, in the teenage years coinciding with the onset of myopia and, most notably, in older adults starting after the onset of presbyopia. It has about one-third the prevalence of bilateral refractive errors of the same magnitude. Importantly, the prevalence of anisometropia is higher in highly ametropic groups, suggesting that emmetropization failures underlying ametropia and anisometropia may be similar. Amblyopia is present in 1-3% of humans and around one-half to two-thirds of amblyopes have anisometropia either alone or in combination with strabismus. The frequent co-existence of amblyopia and anisometropia at a child's first clinical examination promotes the belief that the anisometropia has caused the amblyopia, as has been demonstrated in animal models of the condition. In reviewing the human and monkey literature however it is clear that there are additional paths beyond this classic hypothesis to the co-occurrence of anisometropia and amblyopia. For example, after the emergence of amblyopia secondary to either deprivation or strabismus, anisometropia often follows. In cases of anisometropia with no apparent deprivation or strabismus, questions remain about the failure of the emmetropization mechanism that routinely eliminates infantile anisometropia. Also, the chronology of amblyopia development is poorly documented in cases of 'pure' anisometropic amblyopia. Although indirect, the therapeutic impact of refractive correction on anisometropic amblyopia provides strong support for the hypothesis that the anisometropia caused the amblyopia. Direct evidence for the aetiology of anisometropic amblyopia will require longitudinal tracking of at-risk infants, which poses numerous methodological and ethical challenges. However, if we are to prevent this condition, we must understand the factors that cause it to develop.

Quantitative measurement of interocular suppression in children with amblyopia

In this study we explored the possibility of using a dichoptic global motion technique to measure interocular suppression in children with amblyopia. We compared children (5-16 years old) with unilateral anisometropic and/or strabismic amblyopia to age-matched control children. Under dichoptic viewing conditions, contrast interference thresholds were determined with a global motion direction-discrimination task. Using virtual reality goggles, high contrast signal dots were presented to the amblyopic eye, while low contrast noise dots were presented to the non-amblyopic fellow eye. The contrast of the noise dots was increased until discrimination of the motion direction of the signal dots reached chance performance. Contrast interference thresholds were significantly lower in the strabismic group than in the anisometropic and control group. Our results suggest that interocular suppression is stronger in strabismic than in anisometropic amblyopia.

Interventions for unilateral and bilateral refractive amblyopia

BACKGROUND

Refractive amblyopia is a common cause of reduced visual acuity in childhood, but optimal treatment is not well defined. This review examined the treatment effect from spectacles and conventional occlusion.

OBJECTIVES

Evaluation of the evidence of the effectiveness of spectacles, occlusion or both in the treatment of unilateral and bilateral refractive amblyopia.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 1), MEDLINE (January 1950 to January 2012), EMBASE (January 1980 to January 2012), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to January 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 24 January 2012. We manually searched relevant conference proceedings.

SELECTION CRITERIA

Randomised controlled trials of treatment for unilateral and bilateral refractive amblyopia by spectacles, with or without occlusion, were eligible. We included studies with participants of any age.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed abstracts identified by the searches. We obtained full-text copies and contacted study authors where necessary. Eleven trials were eligible for inclusion. We extracted data from eight. Insufficient data were present for the remaining three trials so data extraction was not possible. We identified no trials as containing participants with bilateral amblyopia. We performed no meta-analysis as there were insufficient trials for each outcome.

MAIN RESULTS

For all studies mean acuity (standard deviation (SD)) in the amblyopic eye post-treatment was reported. All included trials reported treatment for unilateral refractive amblyopia.One study randomised participants to spectacles only compared to no treatment, spectacles plus occlusion compared to no treatment and spectacles plus occlusion versus spectacles only. For spectacles only versus no treatment, mean (SD) visual acuity was: spectacles group 0.31 (0.17); no treatment group 0.42 (0.19) and mean difference (MD) between groups was -0.11 (borderline statistical significance: 95% confidence interval (CI) -0.22 to 0.00). For spectacles plus occlusion versus no treatment, mean (SD) visual acuity was: full treatment 0.22 (0.13); no treatment 0.42 (0.19). Mean difference (MD) between the groups -0.20 (statistically significant: 95% CI -0.30 to -0.10). For spectacles plus occlusion versus spectacles only, MD was -0.09 (borderline statistical significance 95% CI -0.18 to 0.00). For two other trials that also looked at this comparison MD was -0.15 (not statistically significant 95% CI -0.32 to 0.02) for one trial and MD 0.01 (not statistically significant 95% CI -0.08 to 0.10) for the second trial.Three trials reviewed occlusion regimes.One trial looked at two hours versus six hours for moderate amblyopia: MD 0.01 (not statistically significant: 95% CI -0.06 to 0.08); a second trial 2003b reviewed six hours versus full-time for severe amblyopia: MD 0.03 (not statistically significant: 95% CI -0.08 to 0.14) and a third trial looked at six hours versus full-time occlusion: MD -0.12 (not statistically significant: 95% CI -0.27 to 0.03). One trial looked at occlusion supplemented with near or distance activities: MD-0.03 (not statistically significant 95% CI -0.09 to 0.03). One trial looked at partial occlusion and glasses versus glasses only: MD -0.01 (not statistically significant: 95% CI -0.05 to 0.03).

AUTHORS' CONCLUSIONS

In some cases of unilateral refractive amblyopia it appears that there is a treatment benefit from refractive correction alone. Where amblyopia persists there is evidence that adding occlusion further improves vision. Despite advances in the understanding of the treatment of amblyopia it is currently still not possible to tailor individual treatment plans for amblyopia. The nature of any dose/response effect from occlusion still needs to be clarified. Partial occlusion appears to have the same treatment effect as glasses alone when started simultaneously for the treatment of unilateral refractive amblyopia. Treatment regimes for bilateral and unilateral refractive amblyopia need to be investigated further.

Accuracy of referrals from an orthoptic vision screening program for 3- to 4-year-old preschool children

PURPOSE

To determine the accuracy of orthoptist referrals from a preschool-based vision screening program for children 3-4 years of age and to report the outcomes of referred children.

METHODS

This was a retrospective review of records of participants in the preschool vision screening program in the Walsall, United Kingdom, area for the 2006-2007 school year. Screening examinations were performed by orthoptists and included assessment of visual acuity, ocular alignment, ocular motility, and stereoacuity.

RESULTS

For the 2006-2007 school year, 2,830 of 3,623 children (78%) were screened, Of these, 413 were referred to the Hospital Eye Service. Comparison of the screening results and the Hospital Eye Service examination revealed that recorded visual acuities were similar in 81% of subjects and ocular alignment in 94%. Visual acuity was 6/9 or better at the hospital examination in 87% of referred children, with 46% requiring spectacle use only; 17% of referrals were diagnosed with amblyopia.

CONCLUSIONS

Although the Walsall vision screening program diverged from UK national guidelines by testing at an earlier age, there was no evidence that earlier screening led to a large number of incorrect referrals, and early screening may allow for better outcomes. Sensitivity of screening was not tested, and orthoptist screening in the United Kingdom is likely to be more accurate in this age group than nonspecialist or lay screening that is performed in many other areas.

Can human amblyopia be treated in adulthood?

Amblyopia is a common visual disorder that results in a spatial acuity deficit in the affected eye. Orthodox treatment is to occlude the unaffected eye for lengthy periods, largely determined by the severity of the visual deficit at diagnosis. Although this treatment is not without its problems (poor compliance, potential to reduce binocular function, etc) it is effective in many children with moderate to severe amblyopia. Diagnosis and initiation of treatment early in life are thought to be critical to the success of this form of therapy. Occlusion is rarely undertaken in older children (more than 10 years old) as the visual benefits are considered to be marginal. Therefore, in subjects where occlusion is not effective or those missed by mass screening programs, there is no alternative therapy available later in life. More recently, burgeoning evidence has begun to reveal previously unrecognized levels of residual neural plasticity in the adult brain and scientists have developed new genetic, pharmacological, and behavioral interventions to activate these latent mechanisms in order to harness their potential for visual recovery. Prominent amongst these is the concept of perceptual learning--the fact that repeatedly practicing a challenging visual task leads to substantial and enduring improvements in visual performance over time. In the normal visual system the improvements are highly specific to the attributes of the trained stimulus. However, in the amblyopic visual system, learned improvements have been shown to generalize to novel tasks. In this paper we ask whether amblyopic deficits can be reduced in adulthood and explore the pattern of transfer of learned improvements. We also show that developing training protocols that target the deficit in stereo acuity allows the recovery of normal stereo function even in adulthood. This information will help guide further development of learning-based interventions in this clinical group.

Amblyopia

INTRODUCTION

Amblyopia is commonly associated with squint (strabismus) or refractive errors resulting in different visual inputs to each eye during the sensitive period of visual development (<7-8 years of age). The cumulative incidence is estimated at 2% to 4% in children aged up to 15 years.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of interventions to detect amblyopia early? What are the effects of medical treatments for amblyopia? We searched: Medline, Embase, The Cochrane Library, and other important databases up to May 2010 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations, such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 33 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review, we present information relating to the effectiveness and safety of the following interventions: active vision therapy; glasses alone or with occlusion; or penalisation to treat amblyopia; and screening to detect amblyopia early.

Randomised controlled trial of intermittent photic stimulation for treating amblyopia in older children and adults

The treatment of amblyopia is reviewed and it is noted that in addition to conventional 'passive treatment' in children with occlusion, it has been argued that 'active treatment' may be effective in older children and adults. Intermittent photic stimulation (IPS) is one such active treatment. In Study 1, we report a clinical audit of 21 patients treated with IPS, which demonstrated that the maximum improvement is reached after 6 half hour sessions. Study 2 is a double-masked randomised controlled trial comparing IPS with a control treatment in 30 participants aged 10-57 years. Using a sensitive staircase measure of visual acuity (VA), the IPS group improved by about one line (p = 0.0053). The mean improvement was significantly greater (unpaired t-test, p = 0.022) in the IPS group (mean 0.096; S.E.M. 0.029) than in the control group (mean 0.019; S.E.M. 0.022). The improvement occurred in participants with strabismic amblyopia, but not in those with anisometropic amblyopia. Follow up data after about 1 year showed that VA had regressed to pre-treatment levels. The results are discussed within the context of another development in active amblyopia therapy, perceptual learning. The literature on this therapy reveals improvements in VA of about 2.5 lines in older children and adults with anisometropic amblyopia. It is concluded that perceptual learning is likely a better treatment option than IPS for anisometropic amblyopes, and probably also for strabismic amblyopes although a randomised controlled trial is required. It is noted that the existence of effective treatments for adults does not detract from the need to treat amblyopia in younger children.

Change in vision disorders among Hong Kong preschoolers in 10 years

BACKGROUND

To determine the change in refractive error and the prevalence of amblyopia and strabismus among preschool children in Hong Kong over a period of 10 years.

DESIGN

Two cross-sectional population-based studies conducted in 1996 to 1997 (part A) and 2006 to 2007 (part B) PARTICIPANTS: Children attending randomly selected kindergarten participated in the study.

METHODS

Ocular alignment, visual acuity, cover and uncover tests, cycloplegic refraction, slit-lamp and fundi examination were performed under a standardized testing environment.

MAIN OUTCOME MEASURES

The prevalence of amblyopia (best-corrected visual acuity ≤6/12 in one or both eyes, or a bilateral difference of ≥2 best-corrected visual acuity lines), strabismus and significant refractive error (hyperopia ≥+2.50 D; myopia ≥-1.00 D; astigmatism ≥2.00 D) among preschool children.

RESULTS

Of the 601 children in part A of the study, reduced visual acuity was presented in 3.8%; whereas strabismus was found in 1.8%. The commonest type of refractive error was astigmatism in 6.3% of children, followed by hyperopia (5.8%) and myopia (2.3%). Among 823 children in part B, reduced visual acuity was presented in 2.7% of children, and strabismus was found in 1.7%. The commonest type of refractive error was myopia (6.3%), followed by astigmatism (5.7%) and hyperopia (5.1%). The percentage of children having myopia has significantly increased (P = 0.001).

CONCLUSION

A significant increase in myopia has been noted in Hong Kong preschoolers. Visual screening programmes may need to be tailored to correspond to the local population and be adjusted accordingly from time to time.