By Daniel Tilia, BOptom (Hons), MOptom, GradCertOcTher, FBCLA, FAAO
Clinical Research Manager, Principal Research Optometrist
Brien Holden Vision Institute
Some of these risk factors include:
- Parental myopia.1-3
- Excessive near work at close distances.4, 5
- Reduced time outdoors.6
- Ethnicity, with East Asian children at greater risk of developing myopia.1, 7, 8
- Less than age-expected hyperopia.9
- Female gender.7, 10
There is no published evidence that treating pre-myopes, irrespective of risk, is beneficial in terms of myopia progression. The decision to initiate myopia management is therefore very simple—initiate treatment when myopia is first diagnosed. However, there is a lack of conformity in not only diagnosis of myopia, but also with the magnitude of refractive error considered to be myopic.
In 2015, the World Health Organization defined myopia as:
A condition in which the spherical equivalent objective refractive error is ≤ -0.50 diopter (-0.50 D) in either eye.11
More recently, Flitcroft et al.12 proposed an alternate definition for myopia:
A refractive error in which rays of light entering the eye parallel to the optic axis are brought to a focus in front of the retina when ocular accommodation is relaxed. This usually results from the eyeball being too long from front to back, but can be caused by an overly curved cornea and/or a lens with increased optical power. It also is called nearsightedness.
Flitcroft et al.12 also concluded that refraction ≤ -0.50 D merits diagnosis as myopia. Therefore, myopia management should be initiated when the cycloplegic spherical equivalent refraction reaches -0.50 D.
However, non-cycloplegic refraction generally shows more myopia than cycloplegic refraction,13 and so it is possible that a patient may be pre-myopic under cycloplegia but suffer from distance blur. In such cases, the eye care practitioner may consider an optical strategy which shows efficacy in slowing the rate of myopia progression.
An optical correction is required once myopia causes distance blur. The choice of optical strategy is influenced by patient age, parent / patient expectations, preferences and concerns and the clinical skills and experience of the eye care practitioner. Of the optical devices currently available, minimal to reasonable efficacy in slowing myopia can be achieved with progressive addition and bifocal spectacle lenses,14-17 while contact lenses (bifocal / multifocal soft contact lenses and orthokeratology) have generally show greater efficacy than spectacle lenses in slowing myopia.18-25
Atropine is a pharmacological option, and higher concentrations of atropine show excellent efficacy in reducing the rate of myopia progression for both spherical equivalent refraction and axial length.26 However, high concentration atropine is associated with symptoms of photophobia and reduced accommodation,26 and discontinuation of the drug may result in a significant rebound of myopia.27 Low concentration atropine produces fewer symptoms,27, 28 appears to have less rebound effect 27 and shows good efficacy for reducing the rate of myopia progression for spherical equivalent refraction,27, 28 but poorer efficacy for axial length.28, 29
Stopping myopia management means changing the optical correction to either single vision spectacle lenses or contact lenses (soft or rigid gas permeable) and / or ceasing all atropine treatment. The decision to cease myopia management seems simple—stop management when there is little (~-0.25 D per year) or no myopia progression. The complication is the lack of evidence of when this actually occurs.30 While the World Health Organization has at least simplified when to cease atropine treatment by recommending its use be limited to 2 years,11 the decision of when to change the optical correction is more complex.
It is generally accepted that myopia progression reduces with age, and a few studies have shown that myopia stabilises around 14-16 years of age.31, 32 These findings are somewhat tempered by a significant proportion of myopes continuing to progress well into their 20s,31 with university students with high near demands at most risk.33-35 The question of age as a predictor for reduced myopia progression is also complicated by a significant proportion of patients developing late-onset myopia.36 Therefore, age on its own is a poor indicator of when to stop myopia management.
A better strategy is to regularly monitor patients and assess myopia progression via axial length measurements (if possible) every 6 months and cycloplegic refraction every 12 months.30 This strategy also facilitates evaluation of treatment efficacy, providing required information for amending treatment. Close monitoring of patients who have ceased myopia management is crucial to assess whether myopia progression increases, and re-initiating treatment on indication.30
An alternate philosophy is to continue wearing the same myopia management optical correction after myopia progression has ceased. The non-progressing myope still needs an optical correction, and presumably, the patient is well-adapted to the optical correction. The disadvantages of this option are the increased cost of myopia management optical correction and reduction in visual performance compared to single vision options.37 The decision to continue with a myopia management optical correction will be influenced by patient age31 and level of near demand.33-35
In summary, myopia management should be initiated when spherical equivalent cycloplegic refraction reaches -0.50 D and stopped when there is little or no myopia progression. Consideration should be given to continue with myopia management in younger patients or those with high near demands
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- Jones LA, Sinnott LT, Mutti DO, et al. Parental History of Myopia, Sports and Outdoor Activities, and Future Myopia. Investigative ophthalmology & visual science 2007;48:3524-32.
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- Ip JM, Huynh SC, Robaei D, et al. Ethnic Differences in Refraction and Ocular Biometry in a Population-Based Sample of 11-15-Year-Old Australian Children. Eye (London, England) 2008;22:649-56.
- Rudnicka AR, Owen CG, Nightingale CM, et al. Ethnic Differences in the Prevalence of Myopia and Ocular Biometry in 10- and 11-Year-Old Children: The Child Heart and Health Study in England (Chase). Investigative ophthalmology & visual science 2010;51:6270-6.
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- Sun J, Zhou J, Zhao P, et al. High Prevalence of Myopia and High Myopia in 5060 Chinese University Students in Shanghai. Investigative ophthalmology & visual science 2012;53:7504-9.
- World Health Organization – Brien Holden Vision Institute. The Impact of Myopia. In: The Impact of Myopia and High Myopia. Report of the Joint World Health Organization – Brien Holden Vision Institute Global Scientific Meeting on Myopia. Available at: https://www.who.int/blindness/causes/MyopiaReportforWeb.pdf. Accessed: 18 April 2019.
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- Sankaridurg P, He X, Naduvilath T, et al. Comparison of Noncycloplegic and Cycloplegic Autorefraction in Categorizing Refractive Error Data in Children. Acta ophthalmologica 2017;95:e633-e40.
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