Cochrane Eyes and Vision Editor and Optometrist, John Lawrenson blogs about the latest Cochrane evidence on interventions for controlling myopia in children and asks ‘What is the most effective treatment?’
Myopia, a 21st century global public health problem
With myopia (near or shortsightedness) predicted to affect 50% of the world population by 2050, the condition is rapidly becoming a global public health concern. Myopia, which causes distant objects to become blurred, is already reaching epidemic proportions in certain parts of East and South East Asia. For example, in urban areas of South East Asia, over 90% of children are myopic by the time they complete their high school education, an approximate 23% increase over the last decade. Although often regarded as simply a minor inconvenience, high degrees of myopia are associated with sight-threatening eye problems such as myopic degeneration of the retina and retinal detachment.
Interventions to slow myopia
At birth, newborns are usually longsighted (hyperopic), which then slowly declines to the point that by five to seven years of age, children typically have either normal eyesight or a low degree of hyperopia. Myopia is uncommon in children under six even in East Asia, however in high-risk populations the number with myopia increases dramatically after this age, possibly linked to the intensity of the educational system. In recent years, there has been a considerable amount of interest in the development and testing of interventions to slow the rate of progression of myopia. These interventions generally use one of three approaches:
- Optical treatments that use multifocal glasses or contact lenses to achieve a more clearly focussed retinal image
- Specially designed rigid contact lenses (orthokeratology) that are usually worn at night to reshape the cornea at the front of the eye to reduce myopia
- Pharmacological interventions that involve the use of anti-muscarinic eye drops, which act on the eyes focussing system and lead to biochemical changes that slow the rate of eye growth.
The latest evidence
A recently updated Cochrane review included 41 studies with 6772 children, comparing several optical and pharmacological interventions to slow progression of myopia. The review provided moderate certainty evidence that antimuscarinic eye drops, such as atropine were probably an effective treatment for myopia control. However, some children experienced side effects related to the drops, such as focussing difficulties, sensitivity to light and eye discomfort. In one of the largest studies approximately 15% of children stopped therapy due to side effects. Studies investigating interventions such as multifocal spectacles or specialised contact lenses, showed that that these may have a small benefit in slowing myopia.
Where does this leave us?
Atropine eye drops currently seem to be the most effective treatment for myopia control, although there is still uncertainty regarding the optimal dose and duration of therapy. Although lower doses may reduce side effects, this may be associated with a decrease in their effectiveness. Furthermore, the benefit of using antimuscarinic eye drops in combination with spectacle or contact lens interventions needs further clarification.
Advice to parents of children at risk of developing myopia
An increasing number of eye care practitioners are offering a variety of pharmacological and optical interventions to slow the rate of myopia progression. It is therefore important that parents are provided with the most current and relevant evidence on the likely success of these treatments. This updated Cochrane review is therefore very timely. The most effective intervention in the reported studies was atropine eye drops; however, the concentration of atropine used (0.5%, 1%) was higher than the lower dose (0.01%) currently being offered by most practitioners. Furthermore, the studies were conducted in East Asia and it is unclear whether the reported effectiveness would extend to other ethnic groups.
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John Lawrenson has nothing to disclose.