A randomized pilot study of near activities versus non-near activities during patching therapy for amblyopia

Dichoptic Rescue for Spectacle-Flip Sabotage of Anisometropic Amblyopia Therapy

Background

To be successful, amblyopia therapeutic techniques must respond when ingenious (shrewd) amblyopic children sabotage treatment effect by discovering ways(1) to alter those therapy aspects they find frustrating.

Methods

Her guardian consented to IRB-approved study outside typical FDA enrollment guidelines for CureSight dichoptic therapy. Acuity (EVA) and stereopsis was by PEDIG protocols.

Results

A 6-year-old rural Alaska native girl in foster care had previously been diagnosed with anisometropic amblyopia and treated with spectacles and patching but had poor compliance with BCVA 0.9-1.0 logMAR. She demonstrated exceptional creativity and hyperactivity but had no other medical issues. Atropine was prescribed in addition to her spectacles +5.50+1.00x90 and +0.50+1.00x90, but the patient discovered the rare "Spectacle Flip" method that sabotaged therapeutic impact. She had EVA enrollment acuities of logMAR 0.9 right and -0.1 left with stereo 400 seconds of arc. After just one month dichoptic therapy 1.5 hours 6 days per week, acuity improved to logMAR 0.7 and -0.1 with stereo up to 140 second of arc. Four months later acuity was 0.6 right and -0.2 left. Stereoacuity improved from 400 to 200 arc seconds.

Conclusion

Even when conventional compliance methods fail, dichoptic therapy with eye-tracking has the novel and unique potential to improve amblyopia treatment compliance with real-time monitored fixation compliance and confirmation of correct spectacle wear.

Clinical Trial Registration

NCT06165705.

Standard Amblyopia Therapy in Adults with Longstanding Amblyopia Improves Visual Acuity and Contrast Sensitivity

Purpose

Perceptual learning or dichoptic training may result in improved acuity in adult amblyopes. However, for amblyopic children (<18 years), most clinicians recommend standard part-time patching. The purpose of this study was to determine if standard amblyopia therapy results in an enhancement in vision in the amblyopic eye of adults.

Patients and Methods

Fifteen amblyopes (20/30 or worse) were recruited and nine (age (SD) 32.9 (16.31)) with anisometropia or anisometropia and strabismus (ie, combined mechanism amblyopia) completed the study. Previous therapy did not exclude subjects. The subjects received a comprehensive eye exam and wore their best correction for at least four weeks prior to baseline testing. The non-amblyopic eye was patched for 2 hours per day (Amblyopia iNET training for 30 minutes and near/distance activities for 1.5 hours). The subjects had a baseline amblyopia evaluation followed by one visit per week for 12 weeks. At 12 weeks, the treatment was tapered off over one month and the subjects had a final amblyopia evaluation at 24 weeks. Contrast sensitivity was measured at baseline and 12 weeks with the Quick CSF system.

Results

The subjects had a significant improvement in visual acuity across the weeks (p < 0.001). At baseline, weeks 12 and 24, the average logMAR acuities (SE) were 0.55 (0.09), 0.41 (0.08), and 0.38 (0.09), respectively. Weeks 4 to 24 were significantly different (p < 0.001) from baseline. The average acuity improvement over the 24 weeks was 1.7 logMAR lines. There was a significant increase in the area under the log contrast sensitivity function (p = 0.002) and its estimated acuity (p = 0.036) from baseline to 12 weeks.

Conclusion

Standard amblyopia treatment can result in an improvement in visual acuity and contrast sensitivity in adults with longstanding anisometropic or combined mechanism amblyopia even if they had prior therapy.

Durable recovery from amblyopia with donepezil

An elevated threshold for neuroplasticity limits visual gains with treatment of residual amblyopia in older children and adults. Acetylcholinesterase inhibitors (AChEI) can enable visual neuroplasticity and promote recovery from amblyopia in adult mice. Motivated by these promising findings, we sought to determine whether donepezil, a commercially available AChEI, can enable recovery in older children and adults with residual amblyopia. In this open-label pilot efficacy study, 16 participants (mean age 16 years; range 9-37 years) with residual anisometropic and/or strabismic amblyopia were treated with daily oral donepezil for 12 weeks. Donepezil dosage was started at 2.5 or 5.0 mg based on age and increased by 2.5 mg if the amblyopic eye visual acuity did not improve by 1 line from the visit 4 weeks prior for a maximum dosage of 7.5 or 10 mg. Participants < 18 years of age further patched the dominant eye. The primary outcome was visual acuity in the amblyopic eye at 22 weeks, 10 weeks after treatment was discontinued. Mean amblyopic eye visual acuity improved 1.2 lines (range 0.0-3.0), and 4/16 (25%) improved by ≥ 2 lines after 12 weeks of treatment. Gains were maintained 10 weeks after cessation of donepezil and were similar for children and adults. Adverse events were mild and self-limited. Residual amblyopia improves in older children and adults treated with donepezil, supporting the concept that the critical window of visual cortical plasticity can be pharmacologically manipulated to treat amblyopia. Placebo-controlled studies are needed.

National survey of amblyopia treatment in Japan: comparison with amblyopia treatment study results of the pediatric eye disease investigator group

PURPOSE

To investigate the treatment policy for amblyopia in Japan as of 2017 through a survey of multiple facilities and to compare the findings with those obtained by the Amblyopia Treatment Study (ATS) of the Pediatric Eye Disease Investigator Group.

STUDY DESIGN

Questionnaire survey study.

SUBJECTS AND METHODS

A questionnaire was sent to 181 facilities where patients with amblyopia are being treated. The outcomes of the present survey were compared with the results of the ATS study, and the coincidence rates were evaluated.

RESULTS

The questionnaire response rate was 68.0%. The treatment plan that showed the highest agreement between the outcomes of the ATS study and the present study was whether or not treatment was to be given to patients aged 10-15 years who had received no previous treatment; 90% of the facilities answered that they would provide treatment to such patients as well. The next highest agreement was the future treatment of amblyopia with stable visual acuity in the affected eye; 82.6% of the facilities responded that they would reduce the occlusion time. On the other hand, the lowest agreement rate was the follow-up period of the refractive correction for moderate anisometropic amblyopia. The ATS showed "4 months," whereas most of the facilities in the present survey replied "3 months." The agreement rate was 10.8%.

CONCLUSION

The amblyopia treatment in Japan survey did not always agree with the research results of the ATS. Japanese ophthalmologists tend to make treatment plans for amblyopia according to their clinical experience.

Perceptual learning with hand - eye coordination as an effective tool for managing amblyopia: A prospective study

Purpose

Amblyopia is a serious condition resulting in monocular impairment of vision. Although traditional treatment improves vision, we attempted to explore the results of perceptual learning in this study.

Methods

This prospective cohort study included all patients with amblyopia who were subjected to perceptual learning. The presenting data on vision, stereopsis and contrast sensitivity were documented in a pretested online format, and the pre- and post-treatment information was compared using descriptive, cross-tabulation and comparative methods on SPSS 2.2. The mean values were obtained, and P < 0.05 was considered statistically significant.

Results

The cohort consisted of 47 patients (23 females and 24 males) with a mean age of 14.11 ± 7.13 years. A statistically significant improvement was detected in visual acuity after the perceptual learning session, and the median follow-up period was 17 days. Also, significant improvements were observed in stereopsis but not in the visual outcomes among the age groups.

Conclusion

Perceptual learning with hand-eye coordination is an effective method for managing amblyopia. This approach can improve vision in all age groups. However, visual improvement is significantly influenced by ocular alignment.

New treatment for amblyopia based on rules of synaptic plasticity: a randomized clinical trial

Amblyopia resulting from early deprivation of vision or defocus in one eye reflects an imbalance of input from the eyes to the visual cortex. We tested the hypothesis that asynchronous stimulation of the two eyes might induce synaptic plasticity and rebalance input. Experiments on normal adults showed that repetitive brief exposure of grating stimuli, with the onset of each stimulus delayed by 8.3 ms in one eye, results in a shift in perceptual eye dominance. Clinical studies (Clinical trial registration number: ChiCTR2100049130), using popular 3D movies with similar asynchrony between the two eyes (amblyopic eye stimulated first) to treat anisometropic amblyopia, established that just 10.5 h of conditioning over <3 weeks produced improvement that met criteria for successful treatment. The benefits of asynchronous conditioning accumulate over 20-30 45 min sessions, and are maintained for at least 2 years. Finally, we demonstrate that asynchronous binocular treatment alone is more effective than patching only. This novel treatment is popular with children and is some 50 times more efficient than patching alone.

Effects of Vision Therapy on Bilateral Amblyopia Unresponsive to Conventional Treatment: A Retrospective Comparative Study

Background: In this study we aim to determines the effect of our vision therapy program for 7- to 10-year-old patients who exhibit bilateral amblyopia that is no longer responsive to conventional treatment. Methods: Children with bilateral amblyopia between the ages of 7 and 10 treated with vision therapy at the China Medical University Hospital between 2016 and 2019 were retrospectively reviewed. Age and visual acuity-matched bilateral amblyopes are included as a control group. The visual acuity for both groups showed no improvement for more than 3 months with part-time patching and full refraction correction. The initial and final visual acuity, stereopsis, and refractive status were analyzed. Results: Here, 15 cases were included as the treatment group and 16 cases as a control group. At the endpoint, the study group shows a significant improvement in BCVA, with a mean of 0.32 ± 0.15 logMAR (3 lines improvement) versus 0.003 ± 0.19 logMAR (nearly no improvement) for the control group (p < 0.001). The benefits of treatment are most obvious in the first 3 months after treatment (p < 0.001) and last until the end point. Stereoacuity also improves from 190.00 ± 163.34 to 85.00 ± 61.24 arc seconds, which is a 55.26% improvement. Conclusions: Vision therapy, comprising orthoptic therapy, perceptual learning and dichoptic training, is a successful program for increasing visual acuity and stereoacuity in 7- to 10-year-old children with bilateral amblyopia that is unresponsive to conventional treatment.

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.

Characterization, passive and active treatment in strabismic amblyopia: a narrative review

Strabismic amblyopia is characterized by a distorted spatial perception. In this condition, the neurofunctional disorder occurring during first years of life provoke several monocular and binocular anomalies such as crowding, deficits in the accommodative response, contrast sensitivity, and ocular motility abilities. The inhibition of the binocular function of the brain by the misaligned amblyopic eye induces a binocular imbalance leading to interocular suppression and the reduction or lack of stereoacuity. Passive treatments such as occlusion, optical and/or pharmacological penalization, and Bangerter foils has been demonstrated to be potentially useful treatments for strabismic amblyopia. Recent researches have proved new pharmacological options to improve and maintain visual acuity after occlusion treatment in strabismic amblyopia. Likewise, the active vision therapy, in the last years, is becoming a very relevant therapeutic option in combination with passive treatments, especially during and after monocular therapy, in the attempt of recovering the imbalanced binocular vision.

Efficacy of interventions for amblyopia: a systematic review and network meta-analysis

BACKGROUND

Many treatments are currently available for amblyopic patients; although, the comparative efficacy of these therapies is unclear. We conducted a systematic review and network meta-analysis (NMA) to establish the relative efficacy of these treatments for amblyopia.

METHODS

Electronic databases (MEDLINE, EMBASE, Cochrane Library) were systematically searched from inception to Sep. 2019. Only Randomized clinical trials comparing any two or three of the following treatments were included: refractive correction (spectacles alone), patching of 2 h per day (patch 2H), patch 6H, patch 12H, patch 2H + near activities (N), patch 2H + distant activities (D), atropine (Atr) daily, Atr weekly, Atr weekly + plano lens over the sound eye (Plano), optical penalization and binocular therapy. The reviewers independently extracted the data according to the PRISMA guidelines; assessed study quality by Cochrane risk-of-bias tool for randomized trials. The primary outcome measure was the change in best-corrected visual acuity (BCVA) expressed as log MAR lines. Direct comparisons and a Bayesian meta-analysis were performed to synthesize data.

RESULTS

Twenty-three studies with 3279 patients were included. In the network meta-analysis, optical penalization was the least effective of all the treatments for the change of visual acuity, spectacles (mean difference [MD], 2.9 Log MAR lines; 95% credibility interval [CrI], 1.8-4.0), patch 2H (MD, 3.3; 95% CrI, 2.3-4.3), patch 6H (MD, 3.6; 95% CrI, 2.6-4.6), patch 12H (MD, 3.4; 95% CrI, 2.3-4.5), patch 2H + N (MD, 3.7; 95% CrI, 2.5-5.0), patch 2H + D (MD, 3.5; 95% CrI, 2.1-5.0), Atr daily (MD, 3.2; 95% CrI, 2.2-4.3), Atr weekly (MD, 3.2; 95% CrI, 2.2-4.3), Atr weekly + Plano (MD, 3.7; 95% CrI, 2.7-4.7), binocular therapy (MD, 3.1; 95% CrI, 2.0-4.2). The patch 6H and patch 2H + N were better than spectacles ([MD, 0.73; 95% Crl, 0.10-1.40]; [MD, 0.84; 95% CrI, 0.19-1.50]).

CONCLUSIONS

The NMA indicated that the efficacy of the most of the examined treatment modalities for amblyopia were comparable, with no significant difference. Further high quality randomized controlled trials are required to determine their efficacy and acceptability.

SYSTEMATIC REVIEW REGISTRATION

CRD42019119843.

Patching and Suppression in Amblyopia: One Mechanism or Two?

Purpose

To determine if benefits from occlusion therapy are due to decreased suppression from the fellow eye in children with amblyopia.

Methods

Ten newly diagnosed amblyopes (7.2 ± 1.4 years old), two with strabismus and eight with anisometropia, participated. Patients were first given a 2-month period of refractive adaptation, followed by occlusion therapy (i.e., patching their fellow eye with an opaque patch for 4 h/day). Visual acuity of the amblyopic eye and interocular suppression were measured before and after 0.5, 1, 2, 4, and 6 months of occlusion therapy. We quantified interocular suppression with a binocular phase combination task.

Results

Visual acuity (in logMAR) improved from 0.50 ± 0.22 (mean ± SD) to 0.33 ± 0.20 for patients who finished a short-term (2 months) occlusion (A1–A10), from 0.53 ± 0.20 to 0.32 ± 0.22 for patients who finished a medium-term (4 months) occlusion (A1–A9), and from 0.48 ± 0.19 to 0.22 ± 0.10 for patients who finished a long-term (6 months) occlusion (A1–A8). Although their visual acuity significantly improved, their degree of suppression, which was abnormal in all cases, did not change consistently. This was true in all durations of occlusion therapy.

Conclusion

Reduced suppression from the fixing eye might not be result from occlusion therapy.

Simplified updates on the pathophysiology and recent developments in the treatment of amblyopia: A review

Amblyopia is the most common cause of monocular visual impairment affecting 2-5% of the general population. Amblyopia is a developmental cortical disorder of the visual pathway essentially due to abnormal visual stimulus, reaching the binocular cortical cells, which may be multivariate. Ganglion cells are of two types: parvocellular (P cells) and magnocellular (M cells); they are the first step where the light energy is converted in to neural impulse. P cells are involved in fine visual acuity, fine stereopsis, and color vision and M cells are involved in gross stereopsis and movement recognition. Strabismus, refractive error, cataract, and ptosis, occurring during critical period are highly amblyogenic. The critical period extends from birth to 7--8 years. The earlier the clinically significant refractive error and strabismus are detected and treated, the greater the likelihood of preventing amblyopia. Treatment for amblyopia in children includes: optical correction of significant refractive errors, patching, pharmacological treatment, and alternative therapies which include: vision therapy, binocular therapy, and liquid crystal display eyeglasses are newer treatment modalities for amblyopia. Age of starting the treatment is not predictive of outcome, instituting treatment on detection and early detection plays a role in achieving better outcomes. This review aims to give a simplified update on amblyopia, which will be of use to a clinician, in understanding the pathophysiology of the complex condition. We also share the cortical aspects of amblyopia and give recent developments in the treatment of amblyopia.

"Aural Patching" After Bilateral Cochlear Implantation Is Challenging for Children With Prior Long-Term Unilateral Implant Experience

OBJECTIVES

To assess the use of "aural patching" as a strategy to potentially reduce the known persistence of aural preference in children receiving bilateral cochlear implants (CIs) with long inter-implant delays by removing the first device to increase stimulation to the second implanted side.

DESIGN

Children/adolescents who received a second CI at 12.8 ± 3.5 years of age after 9.4 ± 2.9 years of unilateral CI use were asked to remove their first CI for regular periods daily (aural patching). Their compliance was monitored, and asymmetries in speech perception were measured at the end of the study period.

RESULTS

Partial adherence to aural patching over the first few months of bilateral hearing use markedly declined with time. As expected, the group demonstrated asymmetries in speech perception that were not significantly affected by the limited aural patching.

CONCLUSIONS

The aural patching protocol was a challenge to maintain for most children and families studied, reflecting both the expected aural preference for the first implanted ear and their challenges to reverse it.

Validation of an automated-ETDRS near and intermediate visual acuity measurement

BACKGROUND

The aim of this study was to determine the repeatability of an automated-ETDRS (Early Treatment Diabetic Retinopathy Study) near and intermediate visual acuity measurement in subjects with normal visual acuity and subjects with reduced visual acuity. The agreement of automated-ETDRS with gold standard chart-based visual acuity measurement was also studied.

METHODS

Fifty-one subjects were tested (aged 23 to 91 years; 33 subjects with normal visual acuity: 6/7.5 or better; 18 subjects with reduced visual acuity: 6/9 to 6/30). Near and intermediate visual acuity of one eye from each subject was measured with an automated tablet-computer system (M&S Technologies, Inc.) and Precision Vision paper chart in a random sequence. Subjects were retested one week later. Repeatability was evaluated using the 95 per cent limits of agreement (LoA) between the two visits.

RESULTS

Average difference between automated-ETDRS near visual acuity and near visual acuity by paper chart was 0.02 ± 0.10 logMAR (p > 0.05). Agreement of near visual acuity between automated-ETDRS and paper chart was good, with 95 per cent LoA of ±0.19 logMAR. Furthermore, automated-ETDRS near visual acuity showed good repeatability (95 per cent LoA of ±0.20). Mean difference between automated-ETDRS intermediate visual acuity and intermediate visual acuity by paper chart was 0.02 ± 0.10 logMAR (p > 0.05). Agreement of intermediate visual acuity between automated-ETDRS and paper chart was good, with 95 per cent LoA of ±0.20 logMAR. In addition, automated-ETDRS intermediate visual acuity had good repeatability (95 per cent LoA of ±0.16).

CONCLUSION

Automated-ETDRS near and intermediate visual acuity measurement showed good repeatability and agreement with the gold standard chart-based visual acuity measurement. The findings of this study indicate the automated visual acuity measurement system may have potential for use in both patient care and clinical trials.

A Comparison of Patched HOTV Visual Acuity and Photoscreening

Early detection of significant vision problems in children is a high priority for pediatricians and school nurses. Routine vision screening is a necessary part of that detection and has traditionally involved acuity charts. However, photoscreening in which “red eye” is elicited to show whether each eye is focusing may outperform routine acuity testing in pediatric offices and schools. This study compares portable acuity testing with photoscreening of preschoolers, kindergarteners, and 1st-graders in 21 elementary schools. School nurses performed enhanced patched acuity testing and two types of photoscreening in a portable tent. Nearly 1,700 children were screened during spring semester 2004, and 14% had confirmatory exams by community eye care professionals. The results indicate that one form of photoscreening using a Gateway DV-S20 digital camera is significantly more sensitive to children with significant vision problems, as well as being the most cost effective (85% specificity and only $0.11 per child). This suggests that the adaptation of photoscreening into a routine vision screening protocol would be beneficial for efficiently detecting vision problems that could lead to amblyopia.

The challenges of amblyopia treatment

The treatment of amblyopia, particularly anisometropic (difference in refractive correction) and/or strabismic (turn of one eye) amblyopia has long been a challenge for many clinicians. Achieving optimum outcomes, where the amblyopic eye reaches a visual acuity similar to the fellow eye, is often impossible in many patients. Part of this challenge has resulted from a previous lack of scientific evidence for amblyopia treatment that was highlight by a systematic review by Snowdon et al. in 1998. Since this review, a number of publications have revealed new findings in the treatment of amblyopia. This includes the finding that less intensive occlusion treatments can be successful in treating amblyopia. A relationship between adherence to treatment and visual acuity has also been established and has been shown to be influenced by the use of intervention material. In addition, there is growing evidence of that a period of glasses wearing only can significantly improve visual acuity alone without any other modes of treatment. This review article reports findings since the Snowdon's report.

Is There a Critical Period for Amblyopia Therapy? Results of a Study on Older Anisometropic Amblyopes

PURPOSE

Amblyopia, a common cause of low vision, is rarely treated in adults. Improvement in vision has been seen beyond the critical period at times. Hence, this study was taken up to study the effect of minimal occlusion therapy (2-4 hours/day) in anisometropic amblyopic patients in the age group of 12-30 years.

MATERIALS AND METHODS

The study is a prospective, randomized case series of anisometropic amblyopia patients aged 12-30 years who reported in the outpatient department of Hakeem Abdul Hameed Centenary Hospital, New Delhi, from December 2011 to November 2013. Thorough ocular examination and cycloplegic refraction was done to rule out other ocular disease. Anisometropic Amblyopia was diagnosed only after four weeks of spectacle wear. The selected patients were then advised occlusion therapy of 2-4 hours per day of better eye with stress on near visual task. Videogames, computers, mobile phone gaming and colouring in especially designed patterns were used as vision training aids. The outcome measure selected was best corrected visual acuity (BCVA) achieved that remained stable for three consecutive months of occlusion.

RESULTS

Sixty one patients of anisometropic amblyopia were included in the study (32 males and 29 females) aged 12-30 years (mean age 17 years). Mean BCVA at the start of treatment was 20/125 (0.8 log MAR units) and 20/32 (0.2 log MAR units) at the end of the treatment. Thirty three patients (54%) out of 61 had BCVA of 20/20, while 58 patients (95%) had ≥ 20/40 BCVA, 01(1.6%) had 20/50 and 02 (3.27%) had 20/80 BCVA at the end of therapy. The results were statistically significant (p- value <0.0001) with a 95% confidence interval.

CONCLUSION

This study clearly proves that there is no critical period for the treatment in older (12-30 years) anisometropic amblyope. Even 2-4 hours per day of occlusion of better eye with vision training thorough near visual task of amblyopic eye is effective. However, counseling and patient compliance is important for successful outcome of therapy.

Prescribed computer games in addition to occlusion versus standard occlusion treatment for childhood amblyopia: a pilot randomised controlled trial

BACKGROUND

Amblyopia ("lazy eye") is the commonest vision deficit in children. If not fully corrected by glasses, amblyopia is treated by patching or blurring the better-seeing eye. Compliance with patching is often poor. Computer-based activities are increasingly topical, both as an adjunct to standard treatment and as a platform for novel treatments. Acceptability by families has not been explored, and feasibility of a randomised controlled trial (RCT) using computer games in terms of recruitment and treatment acceptability is uncertain.

METHODS

We carried out a pilot RCT to test whether computer-based activities are acceptable and accessible to families and to test trial methods such as recruitment and retention rates, randomisation, trial-specific data collection tools and analysis. The trial had three arms: standard near activity advice, Eye Five, a package developed for children with amblyopia, and an off-the-shelf handheld games console with pre-installed games. We enrolled 60 children age 3-8 years with moderate or severe amblyopia after completion of optical treatment.

RESULTS

This trial was registered as UKCRN-ID 11074. Pre-screening of 3600 medical notes identified 189 potentially eligible children, of whom 60 remained eligible after optical treatment, and were enrolled between April 2012 and March 2013. One participant was randomised twice and withdrawn from the study. Of the 58 remaining, 37 were boys. The mean (SD) age was 4.6 (1.7) years. Thirty-seven had moderate and 21 severe amblyopia. Three participants were withdrawn at week 6, and in total, four were lost to follow-up at week 12. Most children and parents/carers found the study procedures, i.e. occlusion treatment, usage of the allocated near activity and completion of a study diary, easy. The prescribed cumulative dose of near activity was 84 h at 12 weeks. Reported near activity usage numbers were close to prescribed numbers in moderate amblyopes (94 % of prescribed) but markedly less in severe amblyopes (64 %). Reported occlusion usage at 12 weeks was 90 % of prescribed dose for moderate and 33 % for severe amblyopes.

CONCLUSIONS

Computer-based games and activities appear acceptable to families as part of their child's amblyopia treatment. Trial methods were appropriate and accepted by families.

A dichoptic custom-made action video game as a treatment for adult amblyopia

Previous studies have employed different experimental approaches to enhance visual function in adults with amblyopia including perceptual learning, videogame play, and dichoptic training. Here, we evaluated the efficacy of a novel dichoptic action videogame combining all three approaches. This experimental intervention was compared to a conventional, yet unstudied method of supervised occlusion while watching movies. Adults with unilateral amblyopia were assigned to either play the dichoptic action game (n=23; 'game' group), or to watch movies monocularly while the fellow eye was patched (n=15; 'movies' group) for a total of 40hours. Following training, visual acuity (VA) improved on average by ≈0.14logMAR (≈28%) in the game group, with improvements noted in both anisometropic and strabismic patients. This improvement is similar to that obtained following perceptual learning, video game play or dichoptic training. Surprisingly, patients with anisometropic amblyopia in the movies group showed similar improvement, revealing a greater impact of supervised occlusion in adults than typically thought. Stereoacuity, reading speed, and contrast sensitivity improved more for game group participants compared with movies group participants. Most improvements were largely retained following a 2-month no-contact period. This novel video game, which combines action gaming, perceptual learning and dichoptic presentation, results in VA improvements equivalent to those previously documented with each of these techniques alone. Our game intervention led to greater improvement than control training in a variety of visual functions, thus suggesting that this approach has promise for the treatment of adult amblyopia.

Interventions for strabismic amblyopia

BACKGROUND

Amblyopia is reduced visual acuity in one or both eyes in the absence of any demonstrable abnormality of the visual pathway. It is not immediately resolved by the correction of refractive error. Strabismus develops in approximately 5% to 8% of the general population. The aim of treatment for amblyopia is to obtain the best possible level of vision in the amblyopic eye. Different treatment options were examined within the review.

OBJECTIVES

By reviewing the available evidence we wanted to establish the most effective treatment for strabismic amblyopia. In particular this review aimed to examine the impact of conventional occlusion therapy for strabismic amblyopia and to analyse the role of partial occlusion and optical penalisation for strabismic amblyopia.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2013, Issue 12), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to January 2014), EMBASE (January 1980 to January 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to January 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (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 30 January 2014.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) for the treatment of strabismic amblyopia including participants of any age.

DATA COLLECTION AND ANALYSIS

Two authors working independently extracted and entered data into Review Manager 5 and then independently checked the data for errors.

MAIN RESULTS

We included three RCTs in this review. The studies reported mean logMAR visual acuity achieved. Mean difference in visual acuity was calculated. When comparing conventional part-time occlusion (with any necessary glasses), PEDIG 2006 reported that this treatment was more beneficial than glasses alone for strabismic amblyopia; the mean difference between groups was -0.18 LogMAR (statistically significant 95% confidence interval (CI) -0.32 to -0.04). Supplementing occlusion therapy with near activities may produce a better visual outcome compared to non-near activities after four weeks of treatment (PEDIG 2005). The results of the pilot study showed mean difference between groups was -0.17 LogMAR (95% CI -0.53 to 0.19). Results from a larger RCT (PEDIG 2008) are now available, showing that supplementing occlusion therapy with near activities may produce a better visual outcome after eight weeks of treatment; the mean difference between groups was -0.02 LogMAR (95% CI -0.10 to 0.06). One further article ia awaiting assessment as in its current format there is insufficient information to include (Alotaibi 2012).

AUTHORS' CONCLUSIONS

Occlusion, whilst wearing necessary refractive correction, appears to be more effective than refractive correction alone in the treatment of strabismic amblyopia. The benefit of combining near activities with occlusion is unproven. No RCTs were found that assessed the role of either partial occlusion or optical penalisation to refractive correction for strabismic amblyopia.

Visual functions in amblyopia as determinants of response to treatment

PURPOSE

To describe the visual functions in amblyopia as determinants of response to treatment.

METHODS

Sixty-nine patients with unilateral and bilateral amblyopia (114 amblyopic eyes) 3 to 15 years old (mean age: 8.80 ± 2.9 years), 40 males (58%) and 29 females (42%), were included in this study. All patients were treated by conventional occlusion 6 hours per day for mild to moderate amblyopia (visual acuity 0.70 or better) and full-time for 4 weeks followed by 6 hours per day for severe amblyopia (visual acuity 0.8 or worse). During occlusion, near activities requiring hand-eye coordination were advised. The follow-up examination was done at 3 and 6 months. Improvement in visual acuity was evaluated on the logMAR chart and correlated with the visual functions. Statistical analysis was done using Wilcoxon rank sum test (Mann-Whitney U test) and Kruskal-Wallis analysis.

RESULTS

There was a statistically significant association of poor contrast sensitivity with the grade of amblyopia (P < .001). The grade of amblyopia (P < .01), accommodation (P < .01), stereopsis (P = .01), and mesopic visual acuity (P < .03) were found to have a correlation with response to amblyopia therapy.

CONCLUSIONS

The grade of amblyopia (initial visual acuity) and accommodation are strong determinants of response to amblyopia therapy, whereas stereopsis and mesopic visual acuity have some value as determinants.

Pediatric eye disease investigator group amblyopia treatment review

INTRODUCTION

The Pediatric Eye Disease Investigator Group (PEDIG), formed in 1997, has been dedicated to clinical research of eye diseases affecting children. Over the last three years, PEDIG has studied the efficacy of amblyopia treatment regimes, and has followed the long-term outcomes of these regimes. These studies are known as the Amblyopia Treatment Studies (ATS) and have been sorted into eight categories. Four of these have been published and four are still awaiting publication.

METHOD

A survey of ophthalmologists and orthoptists attending a seminar in British Columbia, Canada. They were questioned as to how they treat amblyopia in light of the PEDIG studies.

RESULTS

Ninety percent continue to use patching as their first method of treatment in moderate amblyopia. Over 50% will patch four hours/day or more to begin treatment and 83% will use near exercises to augment the patching. Two thirds will begin patching six or more hours/day in patients with severe amblyopia. Those that use atropine, use it daily rather than on weekends. Most felt that amblyopia could be treated to age 12 years and some thought it could be treated to 14 years.

CONCLUSION

Most ophthalmologists and orthoptists taking the survey have not significantly changed their approach to amblyopia treatment in light of the recent PEDIG studies.

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.

Photorefractive keratectomy in treatment of refractive amblyopia in the adult population

PURPOSE

To evaluate changes in corrected distance visual acuity (CDVA) after photorefractive keratectomy (PRK) in amblyopic cases.

SETTING

Ankara Ataturk Training and Research Hospital 1st Ophthalmology Clinic, Ankara, Turkey.

DESIGN

Retrospective case series.

METHODS

The medical records of cases of anisometropic amblyopia treated by excimer laser PRK were reviewed. Inclusion criteria were no previous refractive correction, occlusion treatment, or chemical penalization before age 15 years. Anisometropic amblyopia was defined as a more than 2-line difference in CDVA and a refractive error difference greater than 3.00 diopters (D) between 2 eyes of the same patient. Final visual acuity measurements were performed at the end of the sixth postoperative month.

RESULTS

The study enrolled 16 hyperopic patients and 34 myopic patients with a mean age of 33.3 years. The mean preoperative spherical equivalent was -7.46 D ± 2.90 (SD) in myopic eyes and +4.15 ± 2.56 D in hyperopic eyes. The differences between the preoperative and postoperative uncorrected distance visual acuity and CDVA were statistically significant (P=.001). The mean CDVA was 0.47 ± 0.17 preoperatively and 0.61 ± 0.19 postoperatively. The CDVA decreased in 3 cases (6%), stayed the same in 12 cases (24%), and increased in 35 cases (70%). There was no statistically significant correlation between the severity of amblyopia and the increase in CDVA (r = 0.20, P=.165).

CONCLUSION

After PRK to eliminate and correct refractive errors in anisometropic amblyopia, visual acuity improved significantly in 70% of adult patients with no previous occlusion or chemical penalization treatment.

Interventions for strabismic amblyopia

BACKGROUND

Amblyopia is reduced visual acuity in one or both eyes in the absence of any demonstrable abnormality of the visual pathway. It is not immediately resolved by the correction of refractive error. Strabismus develops in approximately 5% to 8% of the general population. The aim of treatment for amblyopia is to obtain the best possible level of vision in the amblyopic eye. Different treatment options were examined within the review.

OBJECTIVES

By reviewing the available evidence we wanted to establish the most effective treatment for strabismic amblyopia. In particular this review aimed to examine the impact of conventional occlusion therapy for strabismic amblyopia and to analyse the role of partial occlusion and optical penalisation for strabismic amblyopia.

SEARCH STRATEGY

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 6), MEDLINE (January 1950 to June 2011), EMBASE (January 1980 to June 2011), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to June 2011), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) and ClinicalTrials.gov (www.clinicaltrials.gov). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 1 June 2011.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) for the treatment of strabismic amblyopia including participants of any age.

DATA COLLECTION AND ANALYSIS

Two authors working independently extracted and entered data into Review Manager 5 and then independently checked the data for errors.

MAIN RESULTS

We included three RCTs in this review. The studies reported mean logMAR visual acuity achieved. Mean difference in visual acuity was calculated. When comparing conventional part-time occlusion (with any necessary glasses), PEDIG 2006 reported that this treatment was more beneficial than glasses alone for strabismic amblyopia; the mean difference between groups was -0.18 LogMAR (statistically significant 95% confidence interval (CI) -0.32 to -0.04). Supplementing occlusion therapy with near activities may produce a better visual outcome compared to non-near activities after four weeks of treatment (PEDIG 2005). The results of the pilot study showed mean difference between groups was -0.17 LogMAR (95% CI -0.53 to 0.19). Results from a larger RCT (PEDIG 2008) are now available, showing that supplementing occlusion therapy with near activities may produce a better visual outcome after eight weeks of treatment; the mean difference between groups was -0.02 LogMAR (95% CI -0.10 to 0.06).

AUTHORS' CONCLUSIONS

Occlusion, whilst wearing necessary refractive correction, appears to be more effective than refractive correction alone in the treatment of strabismic amblyopia. The benefit of combining near activities with occlusion is unproven. No RCTs were found that assessed the role of either partial occlusion or optical penalisation to refractive correction for strabismic amblyopia.

Motor cortex reorganization across the lifespan

The brain is a highly dynamic structure with the capacity for profound structural and functional change. Such neural plasticity has been well characterized within motor cortex and is believed to represent one of the neural mechanisms for acquiring and modifying motor behaviors. A number of behavioral and neural signals have been identified that modulate motor cortex plasticity throughout the lifespan in both the intact and damaged brain. Specific signals discussed in this review include: motor learning in the intact brain, motor relearning in the damaged brain, cortical stimulation, stage of development and genotype. Clinicians are encouraged to harness these signals in the development and implementation of treatment so as to maximally drive neural plasticity and functional improvements in speech, language and swallowing.

LEARNING OUTCOMES

Readers will be able to: (1) describe a set of behavioral and neural signals that modulate motor cortex plasticity in the intact and damaged brain; (2) describe the influence of stage of development on plasticity and functional outcomes; and (3) identify a known genotype that alters the capacity for motor learning and brain plasticity.

Perceptual learning as a potential treatment for amblyopia: a mini-review

Amblyopia is a developmental abnormality that results from physiological alterations in the visual cortex and impairs form vision. It is a consequence of abnormal binocular visual experience during the "sensitive period" early in life. While amblyopia can often be reversed when treated early, conventional treatment is generally not undertaken in older children and adults. A number of studies over the last twelve years or so suggest that Perceptual Learning (PL) may provide an important new method for treating amblyopia. The aim of this mini-review is to provide a critical review and "meta-analysis" of perceptual learning in adults and children with amblyopia, with a view to extracting principles that might make PL more effective and efficient. Specifically we evaluate: 1). What factors influence the outcome of perceptual learning? 2). Specificity and generalization - two sides of the coin. 3). Do the improvements last? 4). How does PL improve visual function? 5). Should PL be part of the treatment armamentarium? A review of the extant studies makes it clear that practicing a visual task results in a long-lasting improvement in performance in an amblyopic eye. The improvement is generally strongest for the trained eye, task, stimulus and orientation, but appears to have a broader spatial frequency bandwidth than in normal vision. Importantly, practicing on a variety of different tasks and stimuli seems to transfer to improved visual acuity. Perceptual learning operates via a reduction of internal neural noise and/or through more efficient use of the stimulus information by retuning the weighting of the information. The success of PL raises the question of whether it should become a standard part of the armamentarium for the clinical treatment of amblyopia, and suggests several important principles for effective perceptual learning in amblyopia.

Improving the performance of the amblyopic visual system

Experience-dependent plasticity is closely linked with the development of sensory function; however, there is also growing evidence for plasticity in the adult visual system. This review re-examines the notion of a sensitive period for the treatment of amblyopia in the light of recent experimental and clinical evidence for neural plasticity. One recently proposed method for improving the effectiveness and efficiency of treatment that has received considerable attention is 'perceptual learning'. Specifically, both children and adults with amblyopia can improve their perceptual performance through extensive practice on a challenging visual task. The results suggest that perceptual learning may be effective in improving a range of visual performance and, importantly, the improvements may transfer to visual acuity. Recent studies have sought to explore the limits and time course of perceptual learning as an adjunct to occlusion and to investigate the neural mechanisms underlying the visual improvement. These findings, along with the results of new clinical trials, suggest that it might be time to reconsider our notions about neural plasticity in amblyopia.

Neural mechanisms of recovery following early visual deprivation

Natural patterned early visual input is essential for the normal development of the central visual pathways and the visual capacities they sustain. Without visual input, the functional development of the visual system stalls not far from the state at birth, and if input is distorted or biased the visual system develops in an abnormal fashion resulting in specific visual deficits. Monocular deprivation, an extreme form of biased exposure, results in large anatomical and physiological changes in terms of territory innervated by the two eyes in primary visual cortex (V1) and to a loss of vision in the deprived eye reminiscent of that in human deprivation amblyopia. We review work that points to a special role for binocular visual input in the development of V1 and vision. Our unique approach has been to provide animals with mixed visual input each day, which consists of episodes of normal and biased (monocular) exposures. Short periods of concordant binocular input, if continuous, can offset much longer episodes of monocular deprivation to allow normal development of V1 and prevent amblyopia. Studies of animal models of patching therapy for amblyopia reveal that the benefits are both heightened and prolonged by daily episodes of binocular exposure.

Interventions for unilateral refractive amblyopia

BACKGROUND

Unilateral 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 and or occlusion in the treatment of unilateral refractive amblyopia.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and LILACS. Relevant conference proceedings were manually searched. There were no date or language restrictions. The searches were last run on 7 July 2008.

SELECTION CRITERIA

Randomised controlled trials of treatment for unilateral 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. Eight trials were eligible for inclusion. Data were extracted from seven. No meta-analysis was performed.

MAIN RESULTS

For all studies mean acuity (standard deviation (SD)) in the amblyopic eye post treatment is reported.Comparison: Spectacles only versus no treatment (Clarke 2003). Mean (SD) visual acuity: spectacles group 0.31 (0.17); no treatment group 0.42 (0.19). Mean difference (MD) between groups -0.11 (borderline statistical significance: 95% confidence interval (CI) -0.22 to 0.00).Comparison: Spectacles plus occlusion versus no treatment (Clarke 2003). Mean (SD) visual acuity: full treatment 0.22 (0.13); no treatment 0.42 (0.19). Mean difference between the groups -0.20 (statistically significant: 95% CI -0.30 to -0.10).Comparison: Spectacles plus occlusion versus spectacles only: Clarke 2003 MD -0.09 (borderline statistical significance 95% CI, -0.18 to 0.00); PEDIG 2005b; MD -0.15 (not statistically significant 95% CI -0.32 to 0.02); PEDIG 2006a; MD 0.01 (not statistically significant 95% CI -0.08 to 0.10).Comparison: Occlusion regimes. PEDIG 2003a: 2 hours versus 6 hours for moderate amblyopia: MD 0.01 (not statistically significant: 95% CI -0.06 to 0.08); PEDIG 2003b: 6 hours versus full-time for severe amblyopia: MD 0.03 (not statistically significant: 95% CI -0.08 to 0.14). Stewart 2007a: 6 hours versus full-time occlusion: MD -0.12 (not statistically significant: 95% CI -0.27 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 some evidence that adding occlusion further improves vision. It remains unclear which treatment regimes are optimal for individual patients. The nature of any dose/response effect from occlusion still needs to be clarified.

A randomized trial of near versus distance activities while patching for amblyopia in children aged 3 to less than 7 years

PURPOSE

To determine whether performing near activities while patching for amblyopia enhances improvement in visual acuity.

DESIGN

Randomized clinical trial.

PARTICIPANTS

A total of 425 children, aged 3 to <7 years, with amblyopia (20/40-20/400) that was caused by anisometropia, strabismus, or both, and that persisted after treatment with spectacles.

METHODS

Children were randomized to 2 hours of patching per day with near activities or 2 hours of patching per day with distance activities. Instruction sheets describing common near and distance activities were given to the parents. Study visits were scheduled at 2, 5, 8, and 17 weeks. In weeks without a visit, weekly telephone calls were made to the parent to monitor and encourage compliance during the first 8 weeks.

MAIN OUTCOME MEASURE

Masked assessment of visual acuity by isolated crowded HOTV optotypes at 8 weeks.

RESULTS

At 8 weeks, improvement in amblyopic eye visual acuity averaged 2.6 lines in the distance activities group and 2.5 lines in the near activities group (mean difference in acuity between groups, adjusted for baseline acuity, 0.0 lines 95% confidence interval, -0.3 to 0.3). The 2 groups also appeared statistically similar at the 2-, 5-, and 17-week visits. At the 17-week examination, children with severe amblyopia improved a mean of 3.6 lines with 2 hours of daily patching.

CONCLUSIONS

Performing common near activities does not improve visual acuity outcome when treating anisometropic, strabismic, or combined amblyopia with 2 hours of daily patching. Children with severe amblyopia may respond to 2 hours of daily patching.

Interventions for strabismic amblyopia

BACKGROUND

Amblyopia is reduced visual acuity in one or both eyes in the absence of any demonstrable abnormality of the visual pathway. It is not immediately resolved by the correction of refractive error. Strabismus develops in approximately 5% to 8% of the general population. The aim of treatment for amblyopia is to obtain the best possible level of vision in the amblyopic eye. Different treatment options were examined within the review.

OBJECTIVES

By reviewing available evidence we wanted to establish the most effective treatment for strabismic amblyopia. In particular this review aimed to examine the impact of conventional occlusion therapy for strabismic amblyopia and analyse the role of partial occlusion and optical penalisation for strabismic amblyopia.

SEARCH STRATEGY

We searched CENTRAL, MEDLINE, EMBASE and LILACS in October 2007. There were no language or date restrictions in the electronic searches for trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) for the treatment of strabismic amblyopia including participants of any age.

DATA COLLECTION AND ANALYSIS

Two authors working independently extracted and entered data into Review Manager 4.2 using the double data entry facility to check for errors.

MAIN RESULTS

We included two RCTs. The studies reported mean logMAR visual acuity achieved. Mean difference in visual acuity was calculated. When comparing conventional part-time occlusion (with any necessary glasses), PEDIG 2006 reported this treatment was more beneficial than glasses alone for strabismic amblyopia. Mean difference between groups was -0.18 (statistically significant 95% CI -0.32 to -0.04). Supplementing occlusion therapy with near activities may produce a better visual outcome compared to non-near activities after four weeks of treatment (PEDIG 2005). Mean difference between groups was -0.17 (95% CI -0.53 to 0.19). However, this data is from a pilot study and the full data set will be added to updates of the review when available.

AUTHORS' CONCLUSIONS

Occlusion, whilst wearing necessary refractive correction, appears to be more effective than refractive correction alone in the treatment of strabismic amblyopia. Combining occlusion and refractive correction with near activities may be more effective than occlusion and refractive correction alone. Further study of the role of near activities is necessary before a more definitive conclusion can be made. Results of a full trial are expected within the coming year. No RCTs were found that assessed the role of either partial occlusion or optical penalisation to refractive correction for strabismic amblyopia.

Outcomes of 6 hour part-time occlusion treatment combined with near activities for unilateral amblyopia

PURPOSE

To evaluate the outcome of the part-time occlusion therapy with near activities in monocular amblyopic patients according to gender, age, severity of amblyopia, and the cause of amblyopia.

METHODS

Fifty eight patients who were prescribed part-time occlusion therapy with near activity from July 1998 to October 2004, were included in this retrospective study. All patients were divided into groups by gender, age, severity of amblyopia, and the cause of amblyopia. Main outcome measures were best corrected visual acuity, line improvement, and success rate.

RESULTS

At the end of patch therapy, visual acuity improved from baseline by an average of 3.2+/-2.5 lines (0.33+/-0.26 log MAR), and follow-up period was 19.71+/-14.61 months (1.62+/-1.20 years). At the last follow-up, visual acuity improved from baseline by an average of 3.7+/-2.4 lines (0.38+/-0.26 log MAR), and follow-up period was 37.41+/-25.83 months (3.08+/-2.12 years). The success rate was 86% (50 patients) at the end of patch therapy. In 44 patients out of 50 patients (88%), the visual acuity was maintained. While 43 patients out of 47 patients who were less than 7 years old (91%) achieved success, 7 patients out of 11 patients 7 years or older (64%) achieved success (p=0.035).

CONCLUSIONS

Six-hour part-time occlusion treatment combined with near activities appears to be favorable in treating 58 children during follow-up of mean 3.08 years. The significant factor was the age at initial treatment.

Changes in visual function following optical treatment of astigmatism-related amblyopia

Effects of optical correction on best-corrected grating acuity (vertical (V), horizontal (H), oblique (O)), vernier acuity (V, H, O), contrast sensitivity (1.5, 6.0, and 18.0 cy/deg spatial frequency, V and H), and stereoacuity were evaluated prospectively in 4- to 13-year-old astigmats and a non-astigmatic age-matched control group. Measurements made at baseline (eyeglasses dispensed for astigmats), 6 weeks, and 1 year showed greater improvement in astigmatic than non-astigmatic children for all measures. Treatment effects occurred by 6 weeks, and did not differ by cohort (<8 vs. >or= 8 years), but astigmatic children did not attain normal levels of visual function.

Predicting potential acuities in amblyopes

PURPOSE

Amblyopic patients, or their parents, often want to know the potential for success before committing to treatment. Recent reports have indicated that the pattern visual evoked potential (pVEP) can be used as a predictor of the success of amblyopia therapy. Unfortunately, these studies did not determine if acuity estimates from pVEPs could accurately predict the acuity post-treatment. Furthermore, pVEPs are not always practical to obtain because of the time necessary to acquire the data. Sweep VEPs (sVEP) offer the advantage of rapidly estimating visual acuity in amblyopic patients. In this retrospective study, the relationship between sVEP acuities measured pre-amblyopic therapy and Snellen acuities measured post-amblyopic therapy was determined.

METHODS

Seventeen patients with amblyopia were studied. Monocular sVEP and Snellen acuities were determined pre-amblyopic therapy and Snellen acuities were determined post-amblyopic therapy. An Enfant 4010 computer system was used to produce the stimuli, record the VEPs, and extrapolate the acuity. The stimuli were horizontally oriented, sine wave gratings (11 spatial frequencies from 2 to 24 cpd) with a contrast of 80%, counterphased at 7.5 Hz. Standard VEP recording techniques were employed. Therapy consisted of the full refractive correction and occlusion combined with active vision therapy.

RESULTS

The patients demonstrated a significant improvement in pre- to post-amblyopic therapy Snellen acuities (P < 0.00001). The intraclass correlation coefficient (r (i)) between the pre-therapy sVEP acuities and the post-therapy Snellen acuities was 0.73. A paired t-test did not find a significant difference between the two sets of data (P = 0.94). For the amblyopes in this study, the average difference (+/-SD) in the sVEP acuity estimate and the final Snellen visual acuity was +0.002 +/- 0.123 logMAR acuity lines.

CONCLUSION

The results indicate that pre-amblyopic therapy sVEP acuity can be a good predictor of post-amblyopic therapy Snellen acuity.

Amblyopia

Results from recent randomised clinical trials in amblyopia should change our approach to screening for and treatment of amblyopia. Based on the current evidence, if one screening session is used, screening at school entry could be the most reasonable time. Clinicians should preferably use age-appropriate LogMAR acuity tests, and treatment should only be considered for children who are clearly not in the typical range for their age. Any substantial refractive error should be corrected before further treatment is considered and the child should be followed in spectacles until no further improvement is recorded, which can take up to 6 months. Parents and carers should then be offered an informed choice between patching and atropine drops. Successful patching regimens can last as little as 1 h or 2 h a day, and successful atropine regimens as little as one drop twice a week. Intense and extended regimens might not be needed in initial therapy.

The treatment of amblyopia

Recent studies suggest that children with amblyopia associated with anisometropia, strabismus, or both should be treated initially with best refractive correction until visual acuity is stable. This may take several months, and a proportion of children will achieve equal visual acuity with glasses alone. For residual anisometropic and strabismic amblyopia, the initial choice of patching or atropine should involve the parent and the child. The dose of prescribed patching or atropine may initially be quite modest, such as 2 hours of patching a day or twice weekly atropine. Treatment should be offered to children until at least 12 years of age and possibly to teenagers. Ongoing studies are addressing the role of undertaking near activities while patched and the role of atropine for severe amblyopia and for older amblyopic children. Future studies are needed to investigate the best treatment strategies for residual amblyopia, whether weaning treatment is needed at the end of a course, and how compliance can be enhanced.

Controversy in amblyopia management

BACKGROUND AND PURPOSE

Much has been written about amblyopia treatment. However, there is no consensus on the most efficacious therapeutic modality for amblyopia. The intensity of therapy needed to maximize visual acuity is also widely debated. The diversity of opinions emphasizes that the optimum treatment for amblyopia is unknown. Part of the uncertainty stems from the lack of standardization in the management of amblyopia. The objective of this paper is to conduct an in-depth review of the literature in an attempt to clarify the amblyopia treatment conundrum.

CONCLUSIONS

The treatment of amblyopia in children is frequently discussed in the literature. It is obvious from the literature that there is the need for prospective studies with consistent controls, clear definitions of what constitutes successful therapy endpoints, and standardization of testing procedures.

Contemporary issues in amblyopia treatment

PURPOSE

The aim of this report is to review the contemporary research in amblyopia treatment and how it will affect clinical practice patterns.

METHODS

Topics addressed include prescribing the optimal refractive correction, the most effective treatment, duration and intensity of treatment, regression after treatment, the upper age for treatment, and the chance of the amblyope losing his or her sound eye.

RESULTS AND CONCLUSIONS

The optimal refractive correction is best determined with cycloplegic retinoscopy; pharmacologic penalization can be as effective as patching in children with moderate amblyopia; less-intense treatment regimens have been found to be as effective as more-intense treatment regimens; regression can occur in as many as 25% of all treated patients; some older amblyopes can be treated successfully; and the amblyope has a higher chance of becoming blind than the nonamblyope.