Best options for myopia
Expanding the range of treatments for myopia in children.
Pauline Cho PhD
Although there is no silver bullet solution for progressive myopia in children, there are some reasonably effective myopia control methods currently available, including atropine eye drops, myopia control glasses, myopia control contact lenses and orthokeratology (ortho-k) contact lenses, experts said at the 38th Congress of the ESCRS Virtual.
“Myopic children need different options and it is therefore important for us to keep abreast of current technology and research to offer the best options to our patients,” said Pauline Cho PhD, of the School of Optometry at The Hong Kong Polytechnic University.
Focusing her presentation on optical methods of myopic control including spectacles, lenses and ortho-k, Dr Cho noted that combination therapy of ortho-k with pharmacological treatments holds promise as an effective means of delaying axial elongation in children. The ultimate goal is to prevent progression to high myopia and its associated range of sight-threatening complications, such as maculopathy and retinal detachment.
Dr Cho presented the preliminary one-year results from an ongoing randomised controlled study of children aged from 6-to-11 years old with -1.00 to -4.00D myopia and astigmatism less than 2.50D. Patients were randomly assigned to either combined therapy of atropine 0.01% and ortho-k (AOK) or ortho-k alone (OK). Results at one year showed that the combination of single-dose 0.01% atropine with ortho-k lens wear was well tolerated and has an additive effect in slowing axial elongation compared with monotherapy.
“The study is ongoing but the results are certainly very promising after one year. When we compared the AOK group with an earlier control group from the Retardation of Myopia in Orthokeratology (ROMIO) study we have a very impressive 81% myopia control effect with the combination therapy,” she said.
In terms of soft contact lenses, the defocus incorporated soft contact (DISC) lens has been shown to slow myopia progression in a two-year randomised study (Lam CSY et al. Br J Ophthalmol,2014; 98:40-45). A total of 128 patients completed the study: 65 with DISC and 63 in the control group of single-vision spectacles (SVS). The axial elongation was 0.36 for the SVS group and 0.25 for the DISC group giving a myopia control effect of 31%.
“The authors also reported that subjects who wore the lenses for over eight hours daily obtained a 60% myopia control effect, but this was for only a small number of patients, so we can’t draw any firm conclusions,” said Dr Cho.
Similar results were also obtained by MiSight, a dual-focus soft contact lens in a two-year randomised trial (Ruiz-Pomeda et al. Graefes Arch Clin Exp Ophthalmol. 2018 May; 256(5):1011-1021.). Seventy-four patients completed the follow-up, with axial elongation of 0.28 for MiSight versus 0.45 for the control group, or a 36% myopic control effect. Another multi-centre study involving MiSight (Chamberlain et al, Optometry and Vision Science: August 2019 – Vol. 96, Issue 8: pp 556-567) reported a 52% myopia control effect as compared to a spectacle control group, with no serious adverse events reported.
For spectacles, the defocus incorporated multiple segments spectacle lenses (DIMS) performed well in a two-year study (Lam et al. British Journal of Ophthalmology 2020;104:363-368) with a 60% myopia control effect, said Dr Cho.
Orthokeratology also has a positive track record for effective myopia control in the scientific literature, said Dr Cho.
“There are a lot of robust studies and the overall effects vary from 32% to 63% depending on the methodologies and the subjects recruited,” she said.
Looking at the range of pharmacological treatments for myopia control currently available, Audrey Chia FRANZO, PhD, Head of the Paediatric Ophthalmology Service at Singapore National Eye Centre, said that muscarinic receptor antagonists, and particularly atropine, have been shown to be the most effective.
“Atropine is definitely the most well established with the largest number of published studies. However, it is hoped that with better understanding of the myopisation process that new pharmacological agents might prove useful in the future,” she said.
Pharmacological agents are thought to work by disrupting the signal cascade for axial elongation in the eye, with muscarinic antagonists, beta adrenergic antagonists and adenosine antagonists all having been employed to try to inhibit myopia
progression, she said
The use of atropine is backed by several randomised controlled studies showing a dose-related effect, with higher doses seeming to have a stronger effect on axial elongation than lower doses, said Dr Chia.
Although atropine treatment has been widely adopted in Asia and seems to be safe and effective, there are still remaining areas of uncertainty regarding optimal dosage and targeting population.
Other muscarinic receptor antagonists include tropicamide and cyclopentolate for which there is limited evidence, and 2% pirenzepine, which showed some efficacy in a 2005 study but never really gained traction as an alternative to atropine, she said.
Results of beta adrenergic receptor antagonists such as Timolol and Labetalol have been disappointing overall and have not been pursued.
In the category of adenosine receptor antagonists, a trial of oral 7-Methylxanthine (7-MX) in 2008 found some effect on axial elongation after two years, but further studies are needed to fully assess its safety and effectiveness.