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I read with great interest the article ’The future is near: focus on myopia’, which was a good piece for the time it was published.(1) The prevalence of myopia is high and has increased across Eastern Asia; nearly 50% of urban populations are myopic, with a prevalence of between 12.5% and 90%.(2) Two popular, efficient myopia control techniques available are orthokeratology (OK) lens treatment and atropine eye drops.
OK treatment was reported to reduce myopia progression by up to 51%.(3) Short-term changes with treatment were reportedly reversible. Central corneal thinning was found to correlate with duration of wear, with decreased density of the basal cell after a five-year wear.(4,5) Other long-term effects include a decrease in basal tear secretion and pigment deposition of a corneal iron ring. Low-dose atropine (0.01%–1%) prescribed nightly was reported to have short-sightedness retardation effects of up to approximately 50%.(3) Lower concentrations of atropine were found to reduce rebound upon discontinuation, photophobia and difficulty with near work.
Myopia is a big concern in Eastern Asia. With the increased influence of myopia control treatments, one may wonder whether there will be any long-term effects. At present, applications differ; for instance, United States Food and Drug Administration approved OK therapy for myopia below –6.00 diopters sphere,(6) and atropine application was introduced at 1% concentration for myopia control. As all research studies have used a time frame of within five years, there is a need to further investigate the safety of these treatments for the long term.
1. Tan DT. The future is near: focus on myopia. Singapore Med J 2004; 45:451-5.
2. Rudnicka AR, Kapetanakis VV, Wathern AK, et al. Global variations and time trends in the prevalence of childhood myopia, a systematic review and quantitative meta-analysis: implications for aetiology and early prevention. Br J Ophthalmol 2016; 100:882-90.
3. Holden BA, Wilson DA, Jong M, et al. Myopia: a growing global problem with sight-threatening complications. Community Eye Health 2015; 28:35.
4. Zhong X, Chen X, Xie RZ, et al. Differences between overnight and long-term wear of orthokeratology contact lenses in corneal contour, thickness, and cell density. Cornea 2009; 28:271-9.
5. Chia JY, Ariffin A, Mohidin N, et al. Correlation between duration of orthokeratology lens wear and corneal epithelial and stromal thickness in schoolchildren. Acta Clin Croat 2014; Suppl 2: 9-57.
6. Fadel D. Reshaping Ortho-k. Review of Cornea and Contact Lens 2017. Available at: http://www.reviewofcontactlenses.com/article/reshaping-orthok. Accessed June 13, 2018.