This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.
Both the use of a patch or atropine eye drops are equally suitable methods for improving clarity of vision (visual acuity) in children and young adults with amblyopia (a “lazy eye”).
Amblyopia is a cause of poor vision in childhood that usually affects only one eye, resulting in the individual relying more on the good eye. The standard methods of treatment involve training the weaker eye and promoting its use by covering the strong eye with a patch, or eye drops to blur the vision in the good eye.
This NIHR-funded systematic review evaluated seven trials comparing 1,177 children treated with one of the methods. The findings reinforce existing knowledge that both forms of treatment are similarly effective and that the choice of method is down to child and parental preferences.
Why was this study needed?
Amblyopia is the commonest vision deficit in children, affecting about 2 in 100 children in the UK. It happens when the connection between the eye and the brain is impaired, but the eye itself is healthy.
Patching (occlusion), in which a patch is placed on the stronger eye for a number of hours, is the most common method of treatment. Another accepted method is the use of atropine eye drops (penalisation) which works by temporarily blurring eyesight in the better eye.
The researchers updated the previous version of this review, first published in 2009, using new evidence to compare the effectiveness and safety of patching compared with atropine drops for the treatment of a lazy eye.
What did this study do?
This systematic review included seven trials comparing patching with atropine drops in participants with a lazy eye, regardless of the severity of the condition. Only randomised controlled trials and quasi-randomised controlled trials were selected for inclusion.
The trials included 1,177 participants between 2 and 20 years of age. They were conducted in six countries, but no trials were from the UK. Four new trials were added to the original 2009 review. Treatment for at least two hours per day was given for 17 weeks to two years.
Differences in starting vision between trials and varying treatments prevented meta-analysis and may affect the interpretation of the findings from this review, but the research was of adequate quality.
What did it find?
- Evidence from six of the seven trials showed that both the patch and atropine drops produced an improvement in visual acuity in the weaker eye in the short-term (one to six months) and in the long-term (24 months). The magnitude of improvement varied between trials, and the results could not be pooled.
- There was no meaningful difference between the two treatments in improving visual acuity or binocular function.
- Although use of the patch and the drops were generally well tolerated, the drops were associated with better adherence and quality of life.
- Side effects included reduced visual acuity in the stronger eye, which was more common in those using atropine, but this did not require treatment in nearly all cases. Light sensitivity was also experienced after atropine drops. Eyelid irritation was more common when using a patch.
What does current guidance say on this issue?
The 2016 NICE Clinical Knowledge Summary on the topic of squints in children also covers the treatment of lazy eye.
It suggests that both occlusion and penalisation are options but also mentions switching to penalisation as an alternative to occlusion if wearing a patch is problematic.
What are the implications?
The findings from this review support both occlusion and atropine eyedrops as suitable methods for improving visual acuity and binocular function in those with a lazy eye.
However, using drops may result in better adherence and quality of life for the child. The choice of treatment and balance of risks should be discussed according to child and parental preferences.
Citation and Funding
Li T, Qureshi R and Taylor K. Conventional occlusion versus pharmacologic penalization for amblyopia. Cochrane Database Syst Rev. 2019;(8):CD006460.
This study was funded by a number of sources including the National Institute for Health Research; National Eye Institute, National Institutes of Health, USA; and the John Hopkins Bloomberg School of Public Health, USA.
Bibliography
NHS website. Lazy eye. London: Department of Health; updated 2019.
NICE. Squint in children. Clinical Knowledge Summary. London: National Institute for Health and Care Excellence; 2016.
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