SINGAPORE – While atropine eye drops have been used to treat myopia in children here since the 1990s, there have been concerns about the possible long-term side effects, such as glare and blurring of near vision.

Assurance has now come from a local study that finds that such drops are safe, with no complications 10 to 20 years after treatment.

The Atropine Treatment Long-Term Assessment Study (Atlas) – conducted by researchers at the Singapore National Eye Centre (SNEC) and the Singapore Eye Research Institute (Seri) – is believed to be the first study on the long-term safety of these eye drops.

Used to treat and test various eye conditions, atropine eye drops can be used to slow down the progress of myopia in children and teenagers.

However, in higher doses, the enlarged pupils caused by the drug could make children sensitive to light, and blur their near vision.

Myopia rates here are high, with as many as nine in 10 Singaporean adults expected to be myopic by 2050 – up to a quarter of whom may have high myopia.

Atlas built on two earlier studies – Atropine Treatment of Myopia (Atom) 1, which was conducted between 1996 and 2002, and Atom 2, conducted from 2006 to 2012. Each involved 400 children between the ages of six and 12.

In Atom 1, the 400 myopic children were given either a placebo – such as normal saline solution – or high-dose atropine, of 1 per cent concentration, for two years, followed by a year without treatment.

In Atom 2, 400 children with myopia were given atropine eye drops of varying concentrations – either 0.01 per cent, 0.1 per cent or 0.5 per cent – for two years, followed by a year without treatment.

Those whose myopia worsened by more than 0.5 degree were treated with atropine of 0.01 per cent concentration for another two years.

The Atlas study found that even after 20 years, there was no difference in incidences of complications such as cataracts or myopic macular degeneration between those treated with the 1 per cent concentration atropine and those given the placebo.

Associate Professor Audrey Chia, who heads SNEC’s paediatric ophthalmology and adult strabismus department, said the Atlas findings showed that atropine was safe to use, with no long-term adverse effects.

Adverse effects appeared to be related more to the degree of the participant’s myopia, rather than the treatment the person received, added Prof Chia, principal investigator for the two Atom studies.

The findings were published in peer-reviewed medical journal Jama Ophthalmology in November.

Atlas’ principal investigator, Associate Professor Marcus Ang, said many still have questions about the long-term effects of atropine.

“One thing that I keep getting asked still by my patients and their parents is whether they will get cataracts, or will they lose their ability to read when they’re old,” said Prof Ang, who heads the corneal and external eye disease as well as refractive surgery departments at SNEC. Cataracts are a cloudy area in an eye’s lens and can impair vision.

He noted that among the limitations of the study was that only 71 of those who participated in Atom 1 returned for the Atlas study, while just 158 from the second cohort took part in the new study.

Prof Ang acknowledged that while this was just a fraction of the original cohorts, the researchers ensured that the Atlas participants were representative of the larger group in areas such as age, race and level of myopia.

The study noted that questions remained about the effectiveness of atropine in slowing down myopia.

There were no differences in spherical equivalent or axial length – which are indicators of myopia – or the prevalence of high myopia among the different groups of participants, the researchers said.

This could be due to reasons such as there being no benefit from short-term treatment or rebound effects following the abrupt stoppage of atropine, the study noted.

“These observations raise several research questions that warrant further study – the duration of atropine treatment required to provide a sustained outcome, when treatment can be stopped, and whether to taper dosage or continue treatment into the mid-teenage years,” it said.

Findings by the United States’ Paediatric Eye Disease Investigator Group – published in Jama Ophthalmology in July 2023 – suggested that low-dose atropine eye drops were no more effective than placebos at slowing down the progression of myopia in children treated for two years.

Prof Chia noted, however, that several other studies, conducted in countries such as Japan and China, showed the effectiveness of the drops.

She suggested that the difference in results could be down to other factors, such as lifestyle choices or the difference in myopia progression rates among children of different ethnicities.

Prof Ang stressed that there are now a variety of treatments for myopia, and that it falls upon parents to work with medical professionals in identifying the risk of myopia early in their children and choosing an appropriate intervention method.

“You need to find the best solution for your child, something that your child and you are prepared to do together,” he said.

Myopia treatments

Apart from spectacles and contact lenses, there exist other treatments to treat myopia or slow its progression. Here are some methods.

Atropine eye drops

These work by blocking the muscarinic receptors in the eye, which control how the eye changes focus. This in turn helps reduce the strain myopia places on the eyes. The drops are typically prescribed to children and teenagers.

Laser refractive surgery

This refers to several types of procedures which use lasers to alter the shape of the cornea to correct errors of refraction resulting in myopia. The most well-known of these is laser assisted in-situ keratomileusis (Lasik), which was approved by the US Food and Drug Administration in 1999.

The surgery is typically recommended for those aged 21 and above. Associate Professor Marcus Ang of the Singapore National Eye Centre noted that patients with high myopia, of 800 degrees or more, may be less suitable for Lasik.

Implantable collamer lens (ICL)

The surgery, involving placing a permanent contact lens in the eye, can be used to correct myopia, hyperopia or far-sightedness, and astigmatism, a disorder which causes distorted or blurred vision.

It is suitable for those who are aged at least 21, with myopia of up to 1,900 degrees, though patients should not be pregnant or have conditions such as glaucoma or diabetic eye disease.