Which Myopic Children Will Benefit From Low-Dose Atropine?

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August 1, 2024

By Catherine Tay, BOptom, GradCertPublicHealth

Environmental factors, genetic factors, and patient characteristics are important determinants that may help guide clinicians in recommending myopia intervention strategies. Current strategies include lifestyle advice, myopia control spectacles, soft contact lenses for myopia control, orthokeratology, low-dose atropine, and light-based treatments. A tailored risk assessment of myopia development and progression should be considered for each child.

Atropine is a non-selective muscarinic acetylcholine receptor antagonist. Its mechanism of action in the eye for myopia control remains uncertain, but it is thought to bind to retinal or scleral receptors where chemical signaling processes act to slow eye growth. We know that while higher concentrations of atropine (>0.1%) have been shown to be effective, they also have significant adverse effects and higher rebound rates and are, therefore, not well tolerated¹ or typically used in myopia control. In contrast, lower concentrations of atropine (0.05%, 0.025%, 0.01%) seem to provide reduced side effects but good efficacy² in the reduction of myopia progression. 

When Would Low-Dose Atropine Be Unsuitable?
Anticholinergic medications, such as atropine, have been linked to behavioral changes such as reduced cognitive function, but this is typically only seen in long-term, high-dose, systemic use.³ This would be highly unlikely when used in low concentrations for myopia control, with correct punctal occlusion and eye drop storage. The majority of reported systemic effects from atropine use in children have resulted from those with pre-existing heart conditions such as congenital rubella syndrome and in patients with a history of asthma.⁴ Caution should also be taken in children already using other anti-cholinergic medication to avoid amplifying adverse effects. Atropine is contraindicated in some patients with systemic disorders that are associated with high myopia, including Marfan’s syndrome (which can affect cardiac treatment) and those with cone dystrophies (as it exacerbates photophobia).⁵ Caution must be exercised with the use of high doses of atropine in infants and young children (<5 years) as there is evidence from studies on infant primates that it can lead to arrested ocular development.⁵ 

The effects of atropine eye drops on the ocular system predominantly stem from mydriasis and cycloplegia. Binocular vision and accommodative function should be monitored before and during atropine treatment due to the potential for an esophoric shift and phoria decompensation.⁶ Children may also experience symptoms such as light sensitivity, glare, and haloes, which, in some cases, may affect overall visual performance and quality of life.

Allergic reactions, including periocular dermatitis, lid edema, and madarosis, have also been noted, particularly with increased concentrations of atropine.⁷

Patient and parental preferences and attitudes to pharmacological intervention can be variable. There is still ongoing debate over optimal atropine concentration and a lack of regulation over the quality of compounded forms of atropine.⁸ Parents can become worried about long-term side effects of any form of medication in their children; however, reassuringly, there have yet to be any reported sustained effects from low-dose atropine use.⁹ 

So far, the youngest children included in clinical trials of low-dose atropine have been age 3 and over, with many historical studies targeting children between ages 6-14. Prescribing low-dose atropine in cases outside these age brackets requires parents to understand that efficacy and side effects may vary due to the lack of clinical evidence available. Furthermore, there have been differing outcomes in efficacy across different ethnic populations, with randomized controlled trials¹⁰ showing that 0.01% atropine eye drops were not effective in children of South or East Asian backgrounds but had modest effects in those from European backgrounds. The LAMP study, which included East Asian children in Hong Kong, suggested greater effectivity in this population with 0.05% atropine eye drops. It is still unclear whether the same effectivity with 0.05% concentration would be experienced with other ethnicities and in multi-racial populations.

There is also only limited evidence available for prescribing low-dose atropine in cases of pre-myopia (+0.75 to -0.50D). In such instances, lifestyle advice, which may include increased outdoor time, reduced near work, and more frequent clinical reviews, would be recommended until further data has been released.¹¹

Who Are the Ideal Candidates for Low-Dose Atropine?
Many practitioners favor low-dose atropine for its ease of use and compliance, as well as its ability to be used as an adjunct to other therapies due to its different mechanisms of action. There are fewer studies on dual therapy, with some randomized controlled trials showing an additive effect when combined with orthokeratology.¹²

Myopic children who may not fit the parameters of myopia control spectacle designs and contact lens designs (both orthokeratology and soft contact lenses), such as those with high levels of astigmatism, would be ideal candidates for low-dose atropine. In addition, children who may have had a lack of compliance with other myopia control strategies may be suited to this option. 

Low-dose atropine continues to be a safe and effective option for reducing myopia progression, with impending longitudinal research on concentration effectiveness to further provide clinicians with a targeted, tailored approach to individual treatment strategies. 

 

Catherine Tay is a clinical optometrist who currently works in a suburban private practice and is a clinical teaching instructor for final year students at the University of Melbourne Eyecare Clinic. She is also the Clinical Education Coordinator guiding the Advanced Certificate in Children’s Vision at the Australian College of Optometry. Catherine is CASA accredited and has traveled extensively, working in London and delivering lectures and course material as a volunteer in Myanmar to upskill local refractionists in ocular disease.

 

References

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