Slowing myopia progression
Strategies target different steps along the continuum to pathologic disease
Gemmy Cheung MD
As the world faces an epidemic of high myopia and an increase in the number of people at risk for the blinding sequelae of pathologic myopia, research continues to focus on identifying strategies for preventing myopia and its evolution. Speaking at the 18th Euretina Congress in Vienna, Gemmy Cheung MD provided an update on this topic.
The first target for intervention would be to prevent a non-myopic child from developing myopia, and there is definitely evidence to support recommending increased outdoor time for children, she said. Dr Cheung cited a study from Taiwan that demonstrated a reduction in the incidence of myopia after children were made to go outside the classroom during break time. In addition to increasing time spent outdoors, available evidence supports the safety and efficacy of both topical “ultra” low-dose atropine and orthokeratology.
Dr Cheung said while atropine treatment was first demonstrated effective in the 1980s, it was not adopted because the 1% concentration that was being used caused photophobia and blurred near vision, leading to poor compliance. Now there is evidence from studies with up to five years of follow-up that 0.01% atropine is also effective, as well as safer and better tolerated than the 1% concentration.
Based on this research, ultra low-dose atropine is being used in a lot of clinics and particularly in Asia to prevent myopia progression in children, she said. Nevertheless, there are some logistical challenges that are limiting its use. One obstacle is the absence of a commercially available licensed preparation. There are also questions to be answered about who should be treated, when to start and for how long treatment should continue.
“We still are not sure of what is the perfect way to treat with atropine, and there is still a proportion of children who are poor responders and continue to progress despite atropine treatment,” Dr Cheung said.
Discussing orthokeratology, she said that while it was originally thought that this approach involving overnight wear of a reverse geometric designed rigid gas permeable contact lens only provided temporary improvement in unaided vision, recent evidence and the findings of a meta-analysis suggest orthokeratology has long-term effects on refractive error and axial elongation.
“The mechanism by which orthokeratology might work is not clear, but it has been suggested that the reshaping of the cornea reduces peripheral defocus leading to a lack of a stimulus for the eye to continue to elongate,” Dr Cheung said.
She noted some interesting survey data showing that knowledge and uptake of orthokeratology is much higher among optometrists compared with ophthalmologists.
Aiming to reduce peripheral defocus, strategies using a conventional contact lens or spectacle lens have also been investigated for their potential to prevent myopia progression. Such studies of these modalities are limited in terms of sample size and follow-up duration.
Research to identify effective strategies for preventing progression from high myopia to pathologic myopia is also limited. So far, there is some evidence showing that in patients with myopic choroidal neovascularisation, treatment with anti-VEGF therapy reduces the development of macular atrophy.