Binocular versus standard occlusion or blurring treatment for unilateral amblyopia in children aged three to eight years

Author: Tailor V, Bossi M, Bunce C, Greenwood JA, Dahlmann-Noor A.

Geographical coverage: Not applicable

Sector: Biomedical

Sub-sector: Treatment

Equity focus: Children aged 3-8 years.

Study population: Children between the ages of three and eight years old with unilateral amblyopia.

Review type: Effectiveness review

Quantitative synthesis method: Meta-analysis planned (although not undertaken in practice)

Qualitative synthesis method: Not applicable

Background: Traditional amblyopia treatments, such as patching or pharmacological blurring, often have limited effectiveness. They only enable less than two-thirds of children to achieve a good acuity of 0.20 logMAR in the affected eye, and improvements in stereopsis are minimal. Moreover, adherence to these treatments is generally poor. A novel approach, which involves presenting movies or computer games separately to each eye, could potentially yield better outcomes and improve treatment adherence. This method strives to balance the visual information received by the brain from each eye.

Objectives: To determine whether binocular treatments in children aged three to eight years with unilateral amblyopia result in better visual outcomes than conventional occlusion or pharmacological blurring treatment.

Main findings:

Authors identified one randomised controlled trail (RCT) that compared conventional patching treatment to a novel binocular treatment for amblyopia. This study involved a subset of 68 children who met the age criteria.

After 16 weeks of treatment, authors found that both the binocular and patching groups showed improved acuity in the amblyopic eye. The mean difference was 0.03 logMAR, which was not statistically significant, indicating similar clinical improvements in both groups.

Review authors note higher levels of adherence in the patching group, with 90% achieving over 75% compliance compared to 47% in the binocular (iPad) group. They further found no adverse event of permanent diplopia was reported in either group.

Methodology:

The study incorporated RCTs involving children aged 3-8 years with unilateral amblyopia. Amblyopia was defined as having a best-corrected visual acuity (BCVA) worse than 0.200 logMAR in the amblyopic eye and BCVA 0.200 logMAR or better in the other eye, in the presence of an amblyogenic risk factor like anisometropia, strabismus, or both. Eligible children had undergone cycloplegic refraction and ophthalmic examination, including fundal examination and optical treatment if needed, with stable BCVA in the amblyopic eye despite good adherence with wearing glasses. The study included any type of binocular viewing intervention on any device, such as computer monitors viewed with LCD shutter glasses, hand-held screens, including mobile phones with lenticular prism overlay, or virtual reality displays. Control groups received standard amblyopia treatment, which could include patching or pharmacological blurring of the better-seeing eye. Both full-time and part-time patching regimens were included. Authors excluded children who had received any treatment other than optical treatment; and studies with less than 8‐week follow‐up.

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register), MEDLINE, Embase, ISRCTN, ClinicalTrials.gov, and the WHO ICTRP to 19 November 2020, with no language restrictions.They manually searched the reference lists of the trials included in the review for additional trials. The Science Citation Index was used to identify reports that had cited the studies included in this review. With both strategies, authors aimed to identify any relevant reports or trials that had not been identified by the electronic searches. They did not hand-search journals or conference proceedings specifically for this review.

Two review authors independently screened the results of the search (titles and abstracts) to identify studies that loosely met the inclusion criteria of the review. The authors had abstracts and, where necessary, full-text articles translated into English before making a final decision regarding inclusion or exclusion. Review authors independently examined full-text reports for compliance with inclusion criteria. Any disagreements over which studies to include were resolved by discussion. No consultation with a third review author was required.

Authors used standard methodological procedures expected by Cochrane. The primary outcome of the review was the change from baseline of distance BCVA in the amblyopic eye after 16 (± 2) weeks of treatment, measured in logMAR units on an age‐appropriate acuity test.

Applicability/external validity:

Not applicable, as no substantive results identified.

Geographic focus: No geographic restriction to search.

Summary of quality assessment:

Overall, authors used a rigorous approach to identify, screen, extract data and appraise the included study. Therefore, we have attributed high confidence in the conclusions about the effects of this review.