Treatments to stimulate eye co-operation versus standard patching or blurring treatment for amblyopia (lazy eye) in children aged three to eight years

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

Background
At present, amblyopia ('lazy eye') in children is treated with glasses, followed by either patching or blurring of the better-seeing eye with atropine eyedrops. These treatments are not popular with children, and the amount of patching or eye drops that parents and carers can apply is often less than what was prescribed. Less than two-thirds of children develop normal vision in the lazy eye, and three-dimensional vision also often does not improve. A new treatment that matches the visual information shown to the better eye to the level of vision in the lazy eye may yield better results. Children may find this approach easier to tolerate, as during treatment they play computer games or watch movies through special lenses or on modified computers.

We reviewed published reports about the success of this new treatment, compared with standard patching or eye drop blurring treatment, in children aged three to eight years with lazy eye. We searched all standard sources of information. Two review authors independently reviewed the results of this search. We planned to include only studies reporting results from randomised controlled trials (RCTs), that is those studies comparing the new treatment with a standard treatment, and where children were assigned treatment groups at random (like flipping a coin). Our main result was that we could not identify any such studies. Future updates of this review may include new studies.
We conclude that more research is needed to allow decisions about the new treatment. Whilst we did not find any RCTs, results from studies that did not include a control group are encouraging. We recommend that future research be done in the form of RCTs, and that researchers use acknowledged tests of visual acuity and three-dimensional vision to report the results. It will also be important to publish observations reported by children and families, how much the treatment was used, and if and when the vision in the lazy eye got worse after the treatment was stopped.

Search date
The evidence is current to 14 April 2015.

Authors' conclusions: 

Further research is required to allow decisions about implementation of binocular treatments for amblyopia in clinical practice. Currently there are no clinical trials offering standardised evidence of the safety and effectiveness of binocular treatments, but results from non-controlled cohort studies are encouraging. Future research should be conducted in the form of RCTs, using acknowledged methods of visual acuity and stereoacuity assessment with known reproducibility. Other important outcome measures include outcomes reported by users, compliance with treatment, and recurrence of amblyopia after cessation of treatment.

Read the full abstract...
Background: 

Current treatments for amblyopia in children, occlusion and pharmacological blurring, have had limited success, with less than two-thirds of children achieving good visual acuity of at least 0.20 logMAR in the amblyopic eye, limited improvement of stereopsis, and poor compliance. A new treatment approach, based on the dichoptic presentation of movies or computer games (images presented separately to each eye), may yield better results, as it aims to balance the input of visual information from each eye to the brain. Compliance may also improve with these more child-friendly treatment procedures.

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.

Search strategy: 

We searched the Cochrane Eyes and Vision Group Trials Register (last date of searches: 14 April 2015), the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 3), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to April 2015), EMBASE (January 1980 to April 2015), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), 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.

Selection criteria: 

Two review authors independently screened the results of the search in order to identify studies that met the inclusion criteria of the review: randomised controlled trials (RCTs) that enrolled participants between the ages of three and eight years old with unilateral amblyopia, defined as best-corrected visual acuity (BCVA) worse than 0.200 logMAR in the amblyopic eye, and BCVA 0.200 logMAR or better in the fellow eye, in the presence of an amblyogenic risk factor such as anisometropia, strabismus, or both. Prior to enrolment, participants were to have undergone a cycloplegic refraction and comprehensive ophthalmic examination including fundal examination. In addition, participants had to have completed a period of optical treatment, if indicated, and BCVA in the amblyopic eye had to remain unchanged on two consecutive assessments despite reportedly good compliance with glasses wearing. Participants were not to have received any treatment other than optical treatment prior to enrolment. We planned to include any type of binocular viewing intervention; these could be delivered on different devices including computer monitors viewed with LCD shutter glasses or hand-held screens including mobile phone screens with lenticular prism overlay. Control groups were to have received standard amblyopia treatment; this could include occlusion or pharmacological blurring of the better-seeing eye. We planned to include full-time (all waking hours) and part-time (between 1 and 12 hours a day) occlusion regimens.

Data collection and analysis: 

We planned to use standard methodological procedures expected by The Cochrane Collaboration. We had planned to meta-analyse the primary outcome, that is mean distance BCVA in the amblyopic eye at 12 months after the cessation of treatment.

Main results: 

We could identify no RCTs in this subject area.

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