Halting myopic progression
Myopia treatments are effective but limited as an epidemic looms.
A range of interventions including atropine, orthokeratology and soft contact lenses with myopia control features can all significantly reduce myopia progression when compared with spectacle lenses or placebo, according to Andrzej Grzybowski MD, PhD.
“All of these treatments have been shown to be effective for the management of myopia progression, although we need a lot more studies to address many of the unanswered questions relating to myopia prevention and progression,” he told delegates attending the 17th EURETINA Congress in Barcelona.
Some of those questions include the additive effect of combining atropine with other emerging myopia therapies such as peripheral defocus contact lenses and environmental interventions such as increased outdoor time, said Dr Grzybowski, Professor of Ophthalmology at University of Warmia and Mazury, Olsztyn, Poland. He also noted the need to shed light on questions related to clinical treatment algorithms.
“We need to know more about which children would best benefit from treatment in terms of age, level of myopia, rate of progression and family risk factors, when atropine should be started and stopped and for how long it should be used,” he said.
In a broad overview of current methods to treat myopia, Dr Grzybowski said that the need for effective strategies to tackle myopia has never been greater.
He cited a 2016 study by Holden et al. that predicted a massive increase in the prevalence of myopia and high myopia over the next 30 years. That study warned of the implications for global health systems in managing and preventing myopia-related ocular complications and vision loss among almost 1 billion people with high myopia.
A meta-analysis by Huang et al. in 2016 compared the efficacy of 16 interventions for myopia control in children and concluded that the most effective current interventions were pharmacologic, notably muscarinic antagonists such as atropine and pirenzepine. Certain specially designed contact lenses, including orthokeratology and peripheral defocus modifying contact lenses, had moderate effects, whereas specially designed spectacle lenses showed minimal effect.
In terms of pharmacological treatments, atropine has been in use for many years and has proven its effectiveness, said Dr Grzybowski. The side-effects associated with the use of 1% atropine in early studies, such as photophobia, decreased visual acuity, abnormalities of accommodation and problems with near vision, seem to have been greatly reduced with the use of lower concentration of 0.01%.
A recent five-year trial of a daily dose of 0.01% atropine found it to be an effective first-line treatment for children aged 6-to-12 years with myopic progression of 0.5D in the preceding year, with few side-effects.
“Because atropine appeared more effective in the second year than the first, treatment initially should be continued for at least two years,” he said.
While practically all studies of atropine have involved Asian populations, one Dutch study by Polling et al. in 77 children found atropine 0.5% an effective and sustainable treatment for progressive high myopia. However, there was a high rate of side-effects, said Dr Grzybowski, with photophobia in 72%, reading problems in 38%, and headaches in 22%.
Turning to pirenzepine, this drug provides myopia control with less light sensitivity and fewer near-vision problems than 1% atropine, said Dr Grzybowski.
“However, its long-term use has not been proven to be effective and it is not commercially available at the moment,” he added.
In a Danish study of 800 children over eight years of follow-up, the compound 7-Methylxanthine (7-mx) was shown to reduce myopia progression and excess eye elongation by around 50% in children aged 9-to-13 years, with no major side-effects.
Looking at environmental factors, Dr Grzybowski cited the growing evidence of the role of time spent outdoors as a protective factor against the onset of myopia.
“A lot of studies have now shown that increased time outdoors prevents the onset of myopia and reduces the effects of large amounts of near-work and parental myopia. However, the effects of time outdoors on progression are more controversial and needs further study,” he said.
Andrzej Grzybowski: firstname.lastname@example.org