Atropine and Myopia Control: The ATOM 2 Study7:00 AM
For over a decade, researchers have been reporting great success in slowing down the rate of myopia (or nearsightedness) progression in children by using various concentrations of atropine. It's popularity in countries like China where as many as 80% of children are near-sighted has been steadily growing as more research is published, and with continued positive study results, atropine drops for myopia control may be a treatment we see more and more commonly in the US in future. In the past, atropine has been controversial for use in children because it is a potent pupil dilator -- putting in just one drop a day of the full 1% atropine concentration available in the US causes significant dilation and all its' side effects -- namely severe light sensitivity and an inability to focus clearly up close. That meant that any child taking atropine would have to wear tinted bifocal glasses in order to visually function during their school day. The new release of the ATOM 2 study (ATOM stands for Atropine for the Treatment of Myopia) once again demonstrated great results for slowing down myopia progression with atropine usage, but the best part is that a much lower concentration of the drop may be even more effective, minimizing these unwelcome side effect issues.
|In many Asian countries, myopia is a public health crisis -- the majority of children in these countries are developing myopia at a speed that leaves them dangerously near sighted as an adult. Highly myopic patients are at significantly greater risks for glaucoma, retinal degenerative conditions, and retinal detachments that cause permanent blindness. This advertisement was taken from the Singapore National Eye Centre -- showing just how quickly these countries are embracing new research as they fight to save their children's sight. In the USA we can't get 0.01% atropine commercially at this time.|
Let's Go Back to The Start: ATOM 1
To better understand the new study, let's review about the original ATOM study results that were published back in 2006. This study followed 400 near sighted children split into a control group (given placebo drops to use once daily in one eye) and a treatment group (prescribed Atropine 1% drops to use once daily in one eye). In the first 2 years, the treated group had a whopping 77% reduction in myopic progression as compared to the control group. However, when drops were stopped in year 3 a large rebound effect was seen in the treated group -- they progressed very quickly once they were off of the atropine drops. Because of these results, plus the side effects of atropine, the treatment didn't really take off as a viable means of myopia control in the US.
The ATOM 2 Study
Dr. Donald Tan and the other researchers that participated in both trials knew that atropine worked, but they wanted to find a way to make it a more viable treatment option. The ATOM 2 study looked at comparing lower doses of atropine to see if they could get a similar treatment effect with much fewer side effects. Again 400 myopic children aged 6 to 12 were followed for 5 years, but this time both of their eyes were treated with atropine. The children were split randomly into 3 trial groups: 0.5% Atropine, 0.1% Atropine, and 0.01% Atropine.
|Pupil sizes were measured before treatment (labelled as baseline in the above graphic) in both mesopic (low light) and photopic (bright light) conditions. Children on 0.01% atropine had significantly smaller pupil dilation effect as compared to the larger concentration dosages. Their pupil size increased by about 1 mm on the 0.01% dosage. Only 1% of children taking 0.01% atropine reported glare symptoms, and none of the children had functional near vision loss side effects. via|
At the end of 2 years, all children were stopped for a 1 year washout. Just like was seen in ATOM 1, there was a rebound effect when the atropine was stopped, but the rebound was statistically significantly less in the 0.01% atopine group than in those children on higher doses. 68% of the 0.5% group had a progressive rebound of more than -0.50D during the washout year, compared to 59% of the 0.1% atropine group and only 24% of the 0.01% atropine group. The younger the child, the more likely they were to have a rebound effect.
|Graph showing percent rebound during the year 3 washout. Rebound was defined as > 0.50D increase in myopia during that year. 0.01% atropine group had statistically significantly less rebound than the 0.1% and 0.5% groups (green bars = 0.01%, light blue = 0.1%, and dark blue = 0.5% graphically above). Also note that the older children had much lower rebound risk than younger children, implying that rebound might not be a significant issue if drops are used through the early teenage years. via|
Researchers then restarted any child that progressed more than -0.50D during that washout year on 0.01% atropine for 2 more years. At the end of the study, using the lowest concentration of atropine (0.01%) was shown to be as effective as higher doses in controlling myopia progression, but also had less patients to rebound with discontinuation of the drop, and less side effects of pupil dilation and near focusing issues. The use of 0.01% atropine slowed myopia progression by 50%, and those patients that had a rebound during their washout year that were then retreated had equally effective control once they were placed back on 0.01% atropine.
The results of the study look very favorable for low dose atropine, but some issues remain specifically in the US market. As of today's publication, only 1% atropine is available commercially in the USA. It is possible to get a compounding pharmacy to dilute atropine to a lower concentration, but this can be difficult to find locally, and can result in high prices for the drops. A quick google search shows that a 5 mL bottle (should last about 1 month) cost $38.00 to have compounded in 2014. Another issue is how long should a child be left on atropine? Many researchers theorize for atropine to be an effective solution without rebound, a child would need to be on atropine until they are done growing (the highest risk time for myopia progression). This could mean using it through the early twenties for best control. For most children and parents, using a drop that creates more glare and light sensitivity becomes impractical when the child gets a driver's license, so using even low dose atropine after age 16 could be difficult to continue. Luckily the ATOM 2 study showed that older teens are much less likely to have a rebound effect than younger children. We also don't know exactly how atropine works to slow down myopia progression. Does it somehow signal the eyeball to stop lengthening? We can only theorize at the method of action for why atropine works at this time, but studies show very clearly that it does. If you want to learn more about the current research and theories behind myopia control options, head to the Patient Guides tab and scroll down to the Myopia Control section for a full list of articles.