Myopia

myopia

What is Myopia?

Myopia (short-sightedness) is one of the most investigated areas within vision science. Yet we still do not fully understand why myopia develops and how to stop it.

Possible Causes

  • For myopia to occur the eyeball has to grow longer (change in axial length). 
  • In the past this axial length change was considered to be due to genetics, as myopia tends to run in families. 
  • The rapid increase of myopia over the last 50 years seems to coincide with the increase in literacy and industrialisation in most countries. 
  • This could indicate that high near visual demands and visual stress may also be a causal factor in developing myopia in some individuals. 
  • The general conclusion is that myopia is due to a combination of genetic and environmental factors.

 

Myopia Control

Myopia control is the area of science dedicated to slowing down or stopping the progression, or worsening of myopia in children and young adults. The following table is a compilation of over 30 research papers on myopia control, published up to and including 2013:

myopia table

Management Alternatives

Based on all the accepted research we recommend the following treatment options as most likely to stop or slow the progression of myopia:

1. Good visual hygiene:

  • Good visual habits will reduce any near visual stress that may or may not be contributing to the development or progression of myopia. Either way, reducing near visual stress is a good thing for any visual system.
  • Good visual hygiene includes not getting too close to near work (not inside your knuckle to elbow distance)
  • Take regular breaks by looking away from your near work every 5 mins. If you notice a blur when you first look away it is time to take a longer break.
  • Avoid prolonged close work while tired or sick as this may also increase near point stress and stimulate more myopic development.

2. More outdoor activity:outdoor activity

  • A child with two myopic parents is at a six times greater risk of becoming myopic than a child with no myopic parents. A child with one myopic parent is at three times greater risk. This can be true even if you (the parent) didn’t become myopic as a child. Myopia can also occur without any family history at all.
  • A recent Australian study found that students who combined high levels of near work with low levels of outdoor activity were more likely to become myopic, whereas students who combined low levels of near work with high levels of outdoor activity were more likely to stay longsighted.
  • This was confirmed by a Singapore study which also found that lower amounts of outdoor activity increased the odds of becoming myopic.

3. Spectacle lenses or contact lenses to reduce peripheral hyperopic blur:

  • In a myopic person, the central retina is myopic, but the peripheral retina is actually hyperopic, or longsighted.  It is thought that this stimulates the eyeball to grow causing the myopia to increase.
  • Some new spectacle and contact lens designs aim to reverse detrimental peripheral optics so that theperipheral focus is on, or in front of, the retina – similar to a non-myopic child.

4. Spectacle lenses to reduce near visual stress:near vision stress

  • Wearing plus lenses (or less minus) for close work has the effect of reducing the focusing (accommodative) demand and makes it easier to keep the eyes turned in (converged).This will reduce near visual stress.
  • Studies have found this can be an effective way of slowing / reducing the rate of myopic progression.

5. Ortho-K:

  • The OrthoK technique uses special hard contact lenses which change the curvature of the cornea to neutralise the myopic prescription.
  • These lenses are worn all night and removed each morning.
  • Latest clinical and scientific research shows that OrthoK can slow the progression (worsening) of short-sightedness, or myopia, in childhood by around 50%. In some children OrthoK can even halt the progression of myopia.

6. Atropine treatment:

  • Atropine is an eye drop used to dilate the pupil and temporarily relax the eyes’ focusing mechanism. It has long been acknowledged that atropine also reduces the progression of myopia.
  • Recently it has been shown that low-concentration atropine gives the benefit of slowing the myopic progression without the visual side-effects.

If you require any further information on any of these treatment options please do not hesitate to ask your optometrist.

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