Myopia prevention

Using a low-dose formulation of atropine appears to be safe and effective in slowing the progression of myopia in children, although further studies are needed to address many of the unanswered questions relating to its use in myopia prevention and progression, according to Andrzej Grzybowski MD, PhD. “Low-dose atropine seems to offer an appropriate risk-benefit ratio with no clinically significant visual side-effects balanced against a reasonable and clinically significant 50% reduction in myopia progression,” he told delegates attending the 19th EURETINA Congress in Paris. Dr Grzybowski, Professor of Ophthalmology at University of Warmia and Mazury, Olsztyn, Poland and the Head of the Institute for Research in Ophthalmology, Poznan, Poland noted that data attesting to the clinical efficacy of atropine has been accumulating in the scientific literature in recent years. The reason why we care so much about the increase in myopia prevalence worldwide is high myopia, which accompanies the general trend in myopia, and highly myopic eyes develop many pathological outcomes, which make high myopia a major cause of uncorrectable visual impairment. Pathological outcomes include retinal detachments, myopic macular degeneration, staphyloma and myopic retinoschisis, which are currently difficult and costly to treat. The development of these pathological outcomes is not prevented by correction of the highly myopic refractive errors, and is higher in with higher myopic errors. A meta-analysis by Huang et al in 2016 that compared the efficacy of 16 interventions for myopia control in children concluded that the most effective treatments were atropine and pirenzepine, with orthokeratology and peripheral defocus modifying contact lenses shown to have moderate effect on progression. Furthermore, the side-effects associated with the use of high-dose atropine in early studies seem to have been greatly reduced with the use of lower concentrations of 0.01% and 0.05%, said Dr Grzybowski. The Low-Concentration Atropine for Myopia Progression (LAMP) study compared atropine in concentrations of 0.05%, 0.025% and 0.01% and found that all were well tolerated without an adverse effect on vision-related quality of life. However, 0.05% atropine was most effective in controlling spherical equivalent progression and axial length elongation up to one year, he said. Over the two-year period, the mean SE progression was 0.55±0.86D, 0.85±0.73D, and 1.12±0.85D in the 0.05%, 0.025%, and 0.01% atropine groups, respectively (p=0.015, p<0.001 and p=0.02, respectively, for pairwise comparisons), with mean AL changes over two years of 0.39±0.35mm, 0.50±0.33mm and 0.59±0.38mm (p= 0.04, p<0.001 and p=0.10, respectively). Compared with the first year, the second-year efficacy of 0.05% and 0.025% atropine remained similar (p>0.1), but improved mildly in the 0.01% atropine group (p=0.04). For the phase 1 placebo group, the myopia progression was reduced significantly after switching to 0.05% atropine (SE change, 0.18D in second year vs. 0.82D in first year [p<0.001]; AL elongated 0.15mm in second year vs. 0.43mm in first year [p<0.001]). Accommodation loss and change in pupil size in all concentrations remained similar to the first-year results and were well tolerated. Visual acuity and vision-related quality of life remained unaffected. Over two years, the efficacy of 0.05% atropine observed was double that observed with 0.01% atropine, and it remained the optimal concentration among the studied atropine concentrations in slowing myopia progression. There are still many unresolved questions related to the use of atropine in myopia prevention, said Dr Grzybowski. “We need to know if there is potentially a role for high-dose atropine in cases of rapid progressors? We also do not know the additive effect of combining atropine with other emerging myopia therapies such as peripheral defocus contact lenses or spectacles, and environmental interventions with increased outdoor time which we know is important in helping to prevent myopia in children,” he said. In addition, clinical treatment algorithms are not yet established in terms of which children would most benefit from treatment in terms of age, level of myopia, rate of progression and family risk factors, he said. “We also need more data on when atropine should be started and stopped, and for how long it should it be used. All of these questions need to be addressed in future studies,” he added. A number of randomised controlled trials that are currently being conducted in Europe for low dose atropine should help in this regard, said Dr Grzybowski. He said that a European Network for Myopia Control, made up of experts from different European countries, has recently been established to foster research in the field, and interested parties could contact him for further information. Andrzej Grzybowski: ae.grzybowski@gmail.com

Tags: myopia