Myopia Control

Published on
December 4, 2023
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Myopia, or shortsightedness, is a common condition where the main symptom is blurred distance vision. This occurs because the focussing power of the eye is too strong or the length of the eye is too long. Myopia in the global population is increasing drastically. Currently, 30% of the Australian population is myopic and it is estimated that by 2050 half of the world's population will be myopic.1 While blurry distance vision can be corrected with spectacles or contact lenses, the real issue is the structural changes at the back of the eye which increases the risk of irreversible eye disease.1,2,3 The higher the level of myopia, the higher the risk.

Our optometrists offer a wide range of treatment options to slow the progression of myopia. If you would like to find out more, book an appointment at our Adelaide or Henley Beach practices or speak to our friendly staff.

Assess My Child's Myopia Risk Here

How does myopia affect the eye?

In myopic eyes, light is focused in front of the retina rather than on it, causing blurry distance vision. Myopia tends to manifest in children (average age of onset being 8 years old) with younger age at diagnosis being associated with a higher risk of eye disease – as kids grow, so do their eyes.4,5 Normally our eyes keep growing until the age of 14, after which it stabilises, however it has recently been discovered that 30%develop myopia after the age of 17!1,4,5 In myopic eyes the normal growth patterns are interrupted and the eye continues to grow exponentially resulting in progressive myopia.1

Figure 1. Illustration showing the location of focused light of a normal eye VS a myopic eye. Myopic eyes focus light in front of the retina, causing distance vision to appear blur.

How bad are the risks, even just for low myopia?

Historically, myopia was considered anormal variation of the eye. Now there is a clear distinction between the two types of myopia:

  • Myopia where the power of the eye is lower than –6D
  • High myopia where the power of the eye is greater than –6D

Because myopia is progressive, over time the eye continues to grow longer, and the tissues at the back of the eye become stretched. Therefore, all levels of myopia increase the chance of myopic eye disease such as retinal detachment, cataracts, glaucoma and other retinaldegenerations.2 This escalates as the level of myopia increases and the tissues stretched further, especially once the length of the eye exceeds 26.5mm(‘pathological myopia’).5 1 in 4 people with eyes longer than 26mm are at risk of permanent vision loss, compared to 1 in 25 with eyes smaller than 26mm.3Even if the eye is under 26.5mm long, the risk of glaucoma with myopia is similar to the risk of stroke when smoking over 20 cigarettes a day, and retinal detachments are a frequent occurrence.1,4 Reducing the amount of myopia your child develops keeps the risk as low as possible. It also reduces the thickness of glasses your child will require, as well as their reliance on them.

What are the risk factors for developing myopia?

While a family history of myopia contributes to the development of myopia, other factors are involved.7 Studies have shown that the more time a child spends on activities up close (including on electronic devices) and the less time spent outdoors, the more likely they are to become short-sighted.7 This is thought to partly explain why the number of children developing myopia across the globe is on the rise. Additionally, those who become myopic at a younger age are at greater risk for developing a higher degree myopia.7 Difficulty with the co-ordination of both eyes (binocular vision disorders) have also been linked to progression of myopia.7

How can myopia be controlled?

Unfortunately, standard glasses and contact lenses are ineffective in slowing the progression of short-sightedness.7 However, there are other treatment options that can control growth. At Innovative Eye Care, we take a proactive role in developing a custom treatment regime based on your child’s lifestyle, age and prescription. The main interventions are listed below, as well as basic changes including at least 2hours outdoors each day and limiting near activities (including electronic devices) to 45 minutes at a time.7

Innovative Eye Care’s myopia control treatment options

Orthokeratology

Orthokeratology (or ortho-K) is a type of contact lens wear which has been practiced at Innovative Eye Care for many years. Ortho-K involves wearing a custom-designed contact lens overnight which reversibly and temporarily reshapes the cornea (front surface of the eye) while you sleep, providing clear vision the next day without the need for spectacles or contact lens wear during the day.

As well as being convenient, ortho-K actually slows and, in some cases, stops myopia progression.8,9,10 Ortho-K has been proven to slow myopia progression by 32-100%, depending on the study, or an average 50% reduction.8,9,10 Results in our practice and from other myopia control practices in Australasia show complete halting of myopia progression in some patients.

Atropine eye drops

Atropine is a prescription eye drop that primarily works by relaxing specialised muscles in the eye. It’s been used safely over the decades for a range of eye conditions, including for myopia control. It’s currently thought that the atropine molecule also acts on receptors at the back of the eye that initiate eye growth.10 Evidence has shown that the effect on myopia control is a dose-dependent relationship – the higher the concentration of atropine, the greater the effect on slowing down axial length growth.5,10,11 Side effects like blurry vision and glare are unlikely to occur at the concentrations atropine is prescribed, but can be an issue at higher concentrations. These side effects are reversible upon cessation and have not been shown to cause any long-term changes.11 Currently, atropine used for myopia control is only found at compounding pharmacies as they are not readily available at concentrations below 0.5%. They need to be instilled nightly to prevent progression.

Multifocal contact lenses

Multifocal soft contact lenses are typically used by people over 45 to improve their near vision. The word 'multifocal’ comes from ‘multi’ meaning many and ‘focal’ relating to focus, where multifocal contact lenses can focus light from multiple distances at once, unlike single vision lenses. The retina responds to this pattern of focus by signalling for the slowing of eye growth.10 This refocussing occurs in Ortho-K as well, and this optical property is thought to be responsible for slowing eye growth. Multifocal soft contact lenses have been found to be slightly less effective than ortho-K with only a 40% reduction in myopiaprogression.10

Spectacle lenses

The latest research in myopia control has found that a new spectacle lens design known as DIMS (defocus incorporated multiple segments) is also effective in slowing the growth of the eyeball using similar optics as custom contact lenses.12 DIMS lenses, also known as Hoya MiyoSmart, slow progression by a promising 60% on average, offering children anon-invasive myopia control option.12 Progressive spectacle lenses may also be used to control myopia depending on your child’s binocular vision status, which is tested during the eye examination.13

How do we know it’s working?

Success of a chosen treatment is based on how much myopia progresses throughout. However, not all methods of measuring myopia are created equal. While all optometry practices can quantify whether your child’s prescription has changed with subjective refraction, this doesn’t reliably tell us how much the eye has grown. Since preventing eye growth is the sole reason for myopia control, subjective refraction alone is a poor marker for success. We use the following techniques to accurately assess myopia:

Ocular biometry: Directly measures the axial length of the eye at every visit, down to the micron (1/1,000th of a millimetre)7

Corneal topography and tomography: Maps the shape of the front of the eye to determine its optical power and to fit custom contact lenses like ortho-K.

Objective refraction: Measures myopia when focussing is relaxed, giving a truer refractive reading than when measuredsubjectively.7

Figure 2. Illustration displaying the part of the eye that different eye testing procedures measure.

The most important of these metrics is ocular biometry measuring axial length. It has the least variability and directly relates to the myopic disease process.7 We can compare your child’s axial length against what is normal for a child of their age, and whether they are at a greater risk of disease.

Graph showing axial lengths and their expected progression between the ages 6-13.
Figure 3. Axial length growth chart, showing the normal expected ocular axial lengths. Eyes with large axial lengths have a higher degree of long term risk of vision loss.

Rather than rely on subjective refraction alone, these methods combined give us the complete picture; we know exactly what components of the eye are contributing to myopia. We can then better tailor myopia control strategies for your child and closely monitor for any progression throughout.

References

1) Brien Holden Vision Institute & World Health Organisation. (2016). “The Impact of Myopia and High Myopia.” Report of the Joint World Health Organisation: Brien Holden Institute Global Scientific Meeting on Myopia.

2) Flitcroft, D. I. (2012). “The complex interactions of retinal, optical and environmental factors in myopia aetiology. ”Progress in Retinal and Eye Research31(6): 622-660.

3) Willem, J. et al. (2016) ‘Association of Axial Length with Risk of Uncorrectable Visual Impairment for Europeans with Myopia’. JAMA Ophthalmol. 134(12): 1355-1363.

4) Goldschmidt, E. Jacobsen, N. (2013).‘Genetic and environmental effects on myopia development and progression’. Cambridge Ophthalmological Symposium. 28(1): 126-133.

5) Flitcroft, D. I., et al. (2019).“IMI-Defining and Classifying Myopia: A Proposed Set of Standards for Clinical and Epidemiologic Studies.”InvestOphthalmolVis Sci.60(3)

6) Chen-Wei, P. Ramamurthy, D. Seang-Mei, S.(2011). ‘Worldwide prevalence and risk factors for myopia’. Opthalmic andPhysiological Optics. 32(1).

7) Gifford, K. et al. (2019). “IMI - Clinical Management Guidelines Report”. InvestOphthalVis Sci. 60(3)

8) Na, M. Yoo, A. (2018). “The effect oforthokeratology on axial length elongation in children with myopia: Contralateral comparison study”. Jpn J Ophthalmol. 62(3): 327-334.

9) Hiraoka, T. et al. (2012). “Long-termeffect of overnight orthokeratology on axial length elongation in childhood myopia: a 5-year follow-up study”. Invest Ophthalmol Vis Sci. 53(7): 3913-3919.

10) Wildsoet, C. et al. (2019). “IMI-Interventions for Controlling Myopia Onset and Progression Report”.InvestOphthalmolVis Sci. 60(3).

11) Bullimore, M. A, Richdale, K. (2020).“Myopia Control 2020: Where are we and where are we heading?” OphthalmicPhysiol Opt. 40(3): 254-270.

12) Lam, CSY, et al. “Defocus Incorporated Multiple Segments (DIMS) spectacle lenses slow myopia progression: a 2-yearrandomised clinical trial.” Br J Ophthalmol 104(3):363-368.

13) Cheng, D. et al. (2014). “Effect of bifocaland prismatic bifocal spectacles on myopia progression in children: three-year results of a randomised clinical trial” JAMA Ophthalmol. 132:258-293.

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