Myopia – a global problem
A new trial investigating the effect of atropine in slowing progression of myopia in children is now under way in Ireland, reports Professor James Loughman, Professor of Optometry and Visual Science and Head of the Centre for Eye Research, Technical University, Dublin Ireland.
“The prevalence of myopia is escalating at an alarming rate, not only in Asia, but across the globe.
“Myopia control is now an urgent public health priority given the risk of potentially blinding ocular pathology associated with myopia including cataract, glaucoma, retinal detachment and myopic maculopathy,” said Prof Loughman at Retina 19, a meeting held in Dublin by Fighting Blindness, a patient-led charity that is also sponsoring the trial.
Called the Myopia Outcome Study of Atropine in Children (MOSAIC), the randomised controlled double-masked trial has a recruitment target of 250 children aged 6-to-16 years with progressive myopia. In the initial phase of the trial, half of the patients will receive a daily preservative-free single-unit dose of atropine eye drops at a concentration of 0.01% for two years and the control group will receive a placebo.
In the following 12 months, the placebo group will cross over into active treatment and higher 0.02% doses may be considered for non-responders, said Prof Loughman, who is lead investigator of the trial along with Prof Ian Flitcroft, Temple Street Children’s University Hospital, Dublin, Ireland.
The trial is based on the findings of the Atropine in the Treatment of Myopia (ATOM) 1 and ATOM 2 trials conducted in Singapore. The ATOM 1 trial involved 400 children aged 6-to-12 years of age.
The study showed that atropine eye drops applied daily in one eye over a period of 24 months reduced the progression of myopia by 77% compared with the untreated eye (1.2D vs 0.28D). The ATOM 2 study demonstrated that there was no significant difference in efficacy between atropine at concentrations of 0.5%, 0.1% or 0.01%, and that, even at a concentration as low as 0.01% atropine reduced progression by 59%.
The possibility of using a reduced concentration reduces many of the unwanted side-effects of atropine, such as inability to read and increased light sensitivity requiring the use photochromic sunglasses. Although not generally available, the MOSAIC researchers have acquired the full supply of unpreserved atropine 0.01% and placebo eye drops to complete the trial.
Prof Loughman noted that an important difference between the ATOM studies and the MOSAIC trial is that the current trial will involve European patients. Atropine has an affinity for melanin and the Irish patients will likely include many patients with lighter-coloured irises than the Singaporean patients of the ATOM studies. Moreover, it is the first European trial to use the low-dose 0.01% atropine eye drops.
Prof Loughman noted that the prevalence of myopia has been increasing around the world in recent decades. That is particularly true in some parts of Asia, where myopia now affects up to 96% of teenagers and young adults. That compares to prevalences of 10-to-20% 60-to-80 years ago.
Already the global prevalence of myopia is three times higher than that of obesity, he noted. Currently, there are around 2.5 billion people with myopia worldwide and if the current trend continues, by 2050 the condition will affect five billion people, more than half the world’s population at that point. In addition, the degree of myopia in Asian populations has increased, raising the risk of sight-threatening consequences such as cataract, glaucoma and retinal detachment.
He added that compared to non-myopes, eyes with only -1.0D to -3.0D of myopia have over a two-fold higher lifetime risk of glaucoma, cataract and myopic maculopathy and a three-fold higher risk of retinal detachment. In fact, the ocular risks associated with low myopia are greater than the risk of hypertension and smoking for cardiovascular events like heart attacks and stroke. Moreover, the risks increase with the degree of myopia, and in particular the relative risk for myopic maculopathy, an untreatable condition, is 127-fold higher in eyes with over -7.0D of myopia compared to non-myopes.
“The burden of blindness from myopic maculopathy will increase significantly without efforts to reduce the development of myopia and also improve the management of myopic maculopathy,” Prof Loughman said.
There are several measures that can be taken to prevent or delay the progression of myopia. They include identifying those at risk for the condition, for example those children with a strong family history, poor lifestyle habits or who are less hyperopic than normal for their age. Providing parents with suitable advice, such as encouraging their children to engage in more outdoor activities, is also important.
“If we delay myopia onset, later onset coupled with a slower progression rate will lead to a lower final refractive degree of myopia, a better quality of life and a decreased risk of complications and blindness,” Prof Loughman added.
James Loughman: firstname.lastname@example.org