Strabismus surgery before versus after completion of amblyopia therapy in children

Pattern visual evoked potential and foveal sensitivity in amblyopia

PURPOSE

Amblyopic eyes show impaired visual functions such as poor visual acuity and reduced foveal sensitivity. The purpose of this study was to determine the association between foveal threshold and visual evoked potentials (VEP) in strabismic and anisometropic amblyopia.

METHODS

Forty-five subjects (age range: 7-28 years, 43.3% female) including 15 strabismic and 15 anisometropic amblyopes, and 15 age-similar control subjects participated in this study. Each subject had pattern visual evoked potentials and foveal threshold recorded in each eye using RetiScan (Roland Consult, Germany) and Humphrey Visual Field Analyzer II (HFA II; Carl Zeiss Meditec Inc., Dublin, CA), respectively. These outcomes were compared among the amblyopic eyes, their fellow eyes, and the control eyes.

RESULTS

Compared to the amblyopic eyes (Mean ± SD: 33.4 ± 3.48 dB), the foveal threshold was higher in fellow eyes (37.0 ± 2.04 dB, p = 0.0002) and in control eyes (38.7 ± 0.96 dB, p < 0.0001). Strabismic amblyopes had a lower foveal threshold than anisometropic amblyopes (31.8 ± 3.86 vs. 35.0 ± 2.17 dB, p = 0.005). Relative to the P100 peak time in fellow eyes (1° checks:116.1 ± 9.00 ms; 0.25° checks:118.8 ± 5.67 ms), amblyopic eyes had delayed P100 peak times for both 1° (122.7 ± 11.4 ms, p < 0.0001) and 0.25° (130.4 ± 11.2 ms, p < 0.0001) check sizes. There were also significant differences in P100 peak time between amblyopic and control eyes (1°:122.7 ± 11.4 vs.112.4 ± 5.01 ms, p = 0.15; 0.25°:130.4 ± 11.2 vs.113.9 ± 5.71 ms, p < 0.0001) and between fellow and control eyes (0.25°:118.8 ± 5.67 vs.113.9 ± 5.71 ms, p = 0.009). Amblyopic eyes exhibited lower N75-P100 amplitudes than fellow eyes (1°:12.6 ± 7.96 vs.15.9 ± 8.82 µV, p = 0.01; 0.25°:10.6 ± 6.11 vs. 15.8 ± 10.6 µV, p = 0.001) and control eyes (0.25°: p = 0.0008). Foveal threshold correlated negatively with P100 peak time (1°: r = -0.45, p = 0.002 and 0.25°: r = -0.58, p < 0.0001) and positively with N75-P100 amplitude responses (1°: r = 0.42, p = 0.004 and 0.25°: r = 0.52, p = 0.002).

CONCLUSIONS

Amblyopic eyes showed reduced pattern VEP amplitudes and delayed peak times with significant associations with the foveal sensitivity. However, the VEP measures overlapped extensively between amblyopic and control eyes with no apparent criterion value for optimal discrimination, suggesting that foveal sensitivity might be a better discriminator of amblyopia than pattern VEP.

Altered Brain Activity in Strabismic Amblyopic Children as Determined by Regional Homogeneity: A Resting-State Functional Magnetic Resonance Imaging Study

Objective

Earlier research has determined that amblyopia or strabismus may cause remarkable brain anatomical and functional variations. Nonetheless, thus far, the spontaneous changes in brain activity in children with strabismus amblyopia (SA) remain unclear. The purpose of this study was to determine the association between abnormal brain activity in children with SA and its behavioral manifestations.

Patients and Methods

?A total of 24 children with SA (10 male and 14 female children) as well as 24 healthy controls (HCs), including 10 male and 14 female children were closely matched in sex and age, and examined using resting-state functional magnetic resonance imaging (fMRI). The regional homogeneity (ReHo) technique was applied to evaluate spontaneous cerebral activity variations in children with SA and HCs. Moreover, associations between altered ReHo values in distinct cerebral areas and the degree of strabismus were assessed using Pearson correlation analysis.

Results

Remarkably increased ReHo values were observed in the right lingual, right superior frontal medial, bilateral superior parietal, and right inferior parietal gyri of children with SA compared with HCs. In contrast, mean ReHo values in children with SA were lower in the right cerebellum, left superior frontal gyrus, and left putamen nucleus. Furthermore, esotropia showed a positive correlation with ReHo values of the left putamen.

Conclusion

The anomalous spontaneous activity changes in several brain areas that are caused by SA may indicate neuropathologic mechanisms of visual deficits and oculomotor disorders in children with SA.

Vision screening in newborns and early childhood

We looked at existing recommendations and supporting evidence on the effectiveness of screening for visual disorders in newborns and small infants, and in children between six months and five years of age.We conducted a literature search up to the 5th of August 2019 by using key terms and manual search in selected sources. We summarized the recommendations and the strength of the recommendations when and as reported by the authors. We summarized the main findings of systematic reviews with the certainty of the evidence as reported on the accuracy of screening tests for detecting visual alterations; the efficacy of treatment for improving visual acuity, school performance, and quality of life; and potential harms derived from vision screening and treating visual alterations.Although there is little evidence supporting its validity and effectiveness, examining all newborns for congenital cataract and retinoblastoma through the red reflex examination is widely accepted due to the severity of both diseases and the good outcomes reached by early detection and treatment.Overall, there is a moderate certainty of evidence that visual screening in children between three and five years provides a moderate net benefit, as assessed by the US Preventive Services Task Force: vision screening tests are accurate for detecting amblyopia and its risk factors, and their treatment is associated with visual improvement. There is uncertain evidence on whether vision screening in children under three years of age provides net benefits. Among populations with a low prevalence of vision abnormalities, screening the youngest is associated with an increased rate of false positives, leading to unnecessary additional assessment.

Portable rotating grating stimulation for anisometropic amblyopia with 6 months training

Treatment of grating stimulation has been used in amblyopia for decades, but high dropout rate and inconvenience for daily practice occur in previous studies. We developed a home-based portable system with rotating grating stimulation on a tablet. Thirty anisometropic amblyopic children were randomly allocated into the control or Grating group. They drew contour of the picture under patch of a better eye for 6 months. Best-corrected visual acuity (BCVA), grating acuity (GA), and contrast sensitivity (CS) were assessed at the baseline, 1st, 2nd, 3rd, and 6th months of training. All participants completed the 6-month training. Patched eyes of both groups exhibited no difference. Trained eyes of the control group had significantly slight improvement in BCVA and GA. In particular, the Grating group exhibited significantly higher BCVA, GA, and CS compared with those of the control group at the 3rd and 6th months of training. Moreover, percentage of the Grating group with great improvement (BCVA ≥ 0.3 or CS ≥ 0.3) was significantly larger than those of the control group at the 3rd or 6th months of training. The portable grating stimulation system demonstrates its trainability by no dropout and effectiveness by significant improvements in all assessments through a well experimental design.

Trial Registration: ClinicalTrials.gov NCT04213066, registered 30/12/2019, https://clinicaltrials.gov/ct2/show/NCT04213066.

Core outcome set for three ophthalmic conditions: a healthcare professional and patient consensus on core outcome sets for amblyopia, ocular motility and strabismus (COSAMS Study)

OBJECTIVES

Amblyopia, strabismus and ocular motility disorders are common conditions with significant impact on visual function, appearance and quality of life. We aimed to establish a core set of outcomes for each of the three conditions for use in clinical trials and routine clinical practice.

DESIGN

A comprehensive databank of outcomes was developed from a systematic review of the literature and a series of focus groups with healthcare professionals, researchers, patients and carers. The databank of outcomes was scored in a two-round Delphi Survey completed by two stakeholder groups: healthcare professionals/researchers and patients/carers. Results of the online Delphi were discussed at a face-to-face consensus meeting where the core outcome sets were finalised.

SETTING

UK-wide consultation.

PARTICIPANTS

Researchers, clinicians, patients and carers.

OUTCOME MEASURES

Core outcome sets.

RESULTS

For amblyopia, strabismus and ocular motility, 40/42/33 participants contributed to both rounds of the Delphi; six/nine/seven members attended consensus meetings, respectively. Consensus was reached on ten core outcomes for both amblyopia and ocular motility and nine for strabismus. All three conditions shared the core outcomes: adverse events, cost, vision-related quality of life and ocular alignment. The strabismus and ocular motility disorder core sets included, in addition, measuring the deviation, binocular vision, ocular movement, patient satisfaction and symptoms. The amblyopia set, distinct from the sets for the other two conditions, included best corrected distance and near visual acuity, spherical and cylindrical refraction, compliance and treatment-related and functionality/long-term impacts.

CONCLUSIONS

The study used robust consensus methods to develop a core outcome set for three ophthalmic conditions. Implementation of these core outcome sets in clinical trials and routine clinical practice will ensure that the outcomes being measured and reported are relevant to all stakeholders. This will enhance the relevance of study findings and enable comparison of results from different studies.

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.

Adjustable Versus Nonadjustable Sutures in Strabismus Surgery-Who Benefits the Most?

BACKGROUND

Adjustable sutures have been used in strabismus surgery for more than 40 years, but controversy remains regarding their application. This review sought to analyze studies comparing the efficacy of adjustable sutures (AS) and nonadjustable sutures (NAS) in the treatment of different ocular deviations.

MATERIALS AND METHODS

The PubMed literature database was searched using the keywords 'adjustable sutures' and 'strabismus surgery', yielding a total of 209 results. Only comparative studies were extracted, and the results were divided into three categories: Adult comitant strabismus, childhood comitant strabismus, and paretic/restrictive strabismus.

RESULTS

The search revealed eleven comparative studies on AS versus NAS in adult strabismus, including only one randomized controlled trial. Five of these studies analyzed just the postoperative success rate, three studies analyzed just the reoperation rate, two studies analyzed both the postoperative success and reoperation rates, and one study evaluated achievement of the postoperative target angle. Three of seven studies analyzing postoperative success reported the statically significant superiority of AS over NAS, while four of five studies analyzing reoperation rate indicated a significantly smaller percentage of reoperations with the use of AS. The study covering postoperative target angle as an outcome favored the AS technique. Separately, the search revealed three comparative studies on AS versus NAS in childhood strabismus, one of which reported a statistically significant advantage with AS. Only four comparative studies on AS versus NAS in paretic or restrictive strabismus were found; all showed a tendency for better results with the use of AS but not in a statistically significant fashion. Overall, out of 18 studies analyzed in this review, 17 suggested better clinical results followed the application of AS versus NAS; however, only a minority had statistically significant results.

CONCLUSION

The analysis of available research failed to support AS as the preferable surgery technique over NAS in cases of simple and predictive strabismus. Further research is needed to more precisely determine the group of patients able to benefit the most from AS.

Development of a core outcome set for amblyopia, strabismus and ocular motility disorders: a review to identify outcome measures

BACKGROUND

Core Outcome Sets (COS) are defined as the minimum sets of outcomes that should be measured and reported in all randomised controlled trials to facilitate combination and comparability of research. The aim of this review is to produce an item bank of previously reported outcome measures from published studies in amblyopia, strabismus and ocular motility disorders to initiate the development of COS.

METHODS

A review was conducted to identify articles reporting outcome measures for amblyopia, strabismus and ocular motility disorders. Using systematic methods according to the COMET handbook we searched key electronic bibliographic databases from 1st January 2011 to 27th September 2016 using MESH terms and alternatives indicating the different subtypes of amblyopia, strabismus and ocular motility disorders in relation to treatment outcomes and all synonyms. We included Cochrane reviews, other systematic reviews, controlled trials, non-systematic reviews and retrospective studies. Data was extracted to tabulate demographics of included studies, primary and secondary outcomes, methods of measurement and their time points.

RESULTS

A total of 142 studies were included; 42 in amblyopia, 33 in strabismus, and 68 in ocular motility disorders (one study overlap between amblyopia and strabismus). We identified ten main outcome measure domains for amblyopia, 14 for strabismus, and ten common "visual or motility" outcome measure domains for ocular motility disorders. Within the domains, we found variable nomenclature being used and diversity in methods and timings of measurements.

CONCLUSION

This review highlights discrepancies in outcome measure reporting within published literature for amblyopia, strabismus and ocular motility and it generated an item bank of the most commonly used and reported outcome measures for each of the three conditions from recent literature to start the process of COS development. Consensus among all stakeholders including patients and professionals is recommended to establish a useful COS.

A Review of Cochrane Systematic Reviews of Interventions Relevant to Orthoptic Practice

AIM

To present an overview of the range of systematic reviews on intervention trials pertinent to orthoptic practice, produced by the Cochrane Eyes and Vision group (CEV).

METHODS

We searched the 2016 Cochrane Library database (31.03.2016) to identify completed reviews and protocols of direct relevance to orthoptic practice. These reviews are currently completed and published, available on www.thecochranelibrary.com (free to UK health employees) or via the CEV website (http://eyes.cochrane.org/) .

RESULTS

We found 27 completed CEV reviews across the topics of strabismus, amblyopia, refractive errors, and low vision. Seven completed CEV protocols addressed topics of strabismus, amblyopia, refractive errors, low vision, and screening. We found 3 completed Cochrane Stroke reviews addressing visual field loss, eye movement impairment, and age-related vision loss.

CONCLUSIONS

The systematic review process presents an important opportunity for any clinician to contribute to the establishment of reliable, evidence-based orthoptic practice. Each review has an abstract and plain language summary that many non-clinicians find useful, followed by a full copy of the review (background, objectives, methods, results, discussion) with a conclusion section that is divided into implications for practice and implications for research. The current reviews provide patients/parents/carers with information about various different conditions and treatment options, but also provide clinicians with a summary of the available evidence on interventions, to use as a guide for both clinical practice and future research planning. The reviews identified in this overview highlight the evidence available for effective interventions for strabismus, amblyopia, refractive errors, and low vision or stroke rehabilitation as well as the gaps in the evidence base. Thus, a demand exists for future robust, randomized, controlled trials of such interventions of importance in orthoptic practice.

Childhood amblyopia: current management and new trends

INTRODUCTION OR BACKGROUND

With a prevalence of 2-5%, amblyopia is the most common vision deficit in children in the UK and the second most common cause of functional low vision in children in low-income countries.

SOURCES OF DATA

Pubmed, Cochrane library and clinical trial registries (clinicaltrials.gov, ISRCTN, UKCRN portfolio database).

AREAS OF AGREEMENT

Screening and treatment at the age of 4-5 years are cost efficient and clinically effective. Optical treatment (glasses) alone can improve visual acuity, with residual amblyopia treated by part-time occlusion or pharmacological blurring of the better-seeing eye. Treatment after the end of the conventional 'critical period' can improve vision, but in strabismic amblyopia carries a low risk of double vision.

AREAS OF CONTROVERSY

It is not clear whether earlier vision screening would be cost efficient and associated with better outcomes. Optimization of treatment by individualized patching regimes or early start of occlusion, and novel binocular treatment approaches may enhance adherence to treatment, provide better outcomes and shorten treatment duration.

GROWING POINTS

Binocular treatments for amblyopia.

AREAS TIMELY FOR DEVELOPING RESEARCH

Impact of amblyopia on education and quality of life; optimal screening timing and tests; optimal administration of conventional treatments; development of child-friendly, effective and safe binocular treatments.

Fixation Characteristics of Severe Amblyopia Subtypes: Which One is Worse?

PURPOSE

To determine differences in macular sensitivity and fixation patterns in different subtypes of severe amblyopia.

METHODS

This case-control study enrolled a total of 73 male adults, including 18 with pure strabismic severe amblyopia, 19 with pure anisometropic severe amblyopia, 18 with mixed (strabismic plus anizometropic) severe amblyopia, and 18 healthy controls. MP-1 microperimetry was used to evaluate macular sensitivity, location of fixation, and stability of fixation.

RESULTS

Mean macular sensitivity, stability of fixation, and location of fixation were significantly worse in all amblyopia subtypes when compared with healthy controls. Intergroup comparisons between amblyopia subtypes revealed that mean macular sensitivity, stability of fixation, and location of fixation were significantly worse in pure strabismic and mixed amblyopic eyes when compared with pure anisometropic amblyopic eyes.

CONCLUSIONS

Strabismus seems to be a worse prognostic factor in severe amblyopia than anisometropia in terms of fixation characteristics and retinal sensitivity.

Strabismus surgery before versus after completion of amblyopia therapy in children

BACKGROUND

Normal visual development occurs when the brain is able to integrate the visual input from each of the two eyes to form a single three-dimensional image. The process of development of complete three-dimensional vision begins at birth and is almost complete by 24 months of age. The development of this binocular vision is hindered by any abnormality that prevents the brain from receiving a clear, similar image from each eye, due to decreased vision (e.g. amblyopia), or due to misalignment of the two eyes (strabismus or squint) in infancy and early childhood. Currently, practice patterns for management of a child with both strabismus and amblyopia are not standardized.

OBJECTIVES

To study the functional and anatomic (ocular alignment) outcomes of strabismus surgery before completion of amblyopia therapy as compared with surgery after completion of amblyopia therapy in children under seven years of age.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 6), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to July 2014), EMBASE (January 1980 to July 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to July 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 24 July 2014. A manual search for articles from a review of the references of the selected publications and conference abstracts was completed to identify any additional relevant studies.

SELECTION CRITERIA

We searched for randomized controlled trials (RCTs) that provided data on strabismus surgery in children less than seven years of age, performed after initiation of, but before completion of amblyopia therapy, as compared with strabismus surgery after completion of amblyopia therapy.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies identified from the electronic and manual searches.

MAIN RESULTS

There were no RCTs that fit our inclusion criteria and so no analysis was possible.

AUTHORS' CONCLUSIONS

As there are no RCTs currently available and the best existing evidence is only from non-randomized studies, there is a need for prospective RCTs to investigate strabismus surgery in the presence of strabismic amblyopia. The optimal timing of when to perform strabismus surgery in children with amblyopia is unknown.