Myopia

As optometrists who focuses on children’s vision, we often see parents who are concerned about their child becoming short-sighted.  

Myopia presents with blurry distance vision, but generally gives clear vision at near.   In high myopia, even near vision is affected as objects must be extremely close for the eyes to see clearly and the patients cannot read without their glasses prescribed for distance.  Parents and teachers will often be able to detect myopia in a child by simply noticing how the child is looking into the distance.  Squinting or “screwing up the eyes” is a common behaviour, as well as the preference for bringing ipads and books closer or moving closer to the TV and computers.

Parents are usually concerned about myopia because this usually means your child needs to start wearing galsses pretty much all the time to see clearly in the distance.  Although this can understandably be distressing news, as optometrists we are more concerned about the risk factors associated with high myopia.  We don’t want to see children develop myopia because we know that patients with  greater than -5 dioptres (that’s the number in your glasses) are at increased risk of developing retinal detachment, cataracts, glaucoma and blindness.  The younger they are when they first develop myopia, the higher the chance they will have high myopia.

Sadly, the incidence of global myopia is increasing sharply.  The global prevalance of myopia in 2010 was  25% of the world’s population and we expect this to rise to 50% by 2050.  Here are some scary statistics of myopia:

  • 31% of Australian school age children (Sydney Myopia Eye Study, 2013)
  • 96.5% of South Korean 19 year old teenagers (2012)
  • 95.9% of Taiwan university students (2008)
  • 42% in USA (2009)

Why Is My Child Becoming Myopic?

There are many studies underway to understand why myopia develops, why it progresses and what we can do as optometrists to slow it down.  Whilst myopia is a complex condition, we do know that there are both genetic and environmental factors at play.

  • Having one parent who is already myopic increases the risk factor by 3x
  • Having two parents who are myopic increases the risk factor by 6x
  • If the child is already myopic, this increases the risk factor to “high”
  • Inaccurate teaming (excessive convergence) increases the risk factor to “high”
  • Inaccurate focusing (accommodative insufficiency) increases the risk factor to “high”
  • Daily time spent outdoors <1.6 hours increases the risk factor to “high”
  • Excessive near work 3+ increases the risk factor to “high”

The Physiological Explanation For Myopia

One popular theory related to myopia progression suggests a correlation to hyperopic defocus in the peripheral retina.    This hyperopic defocus increases the growth of the eye ball which explains the “minus” prescription required to correct the resulting blurry vision for distance.

A common question asked by parents is, “Can you keep the prescription weaker to stop it from getting worse”.  The concern here is clearly that parents are often concerned that myopic power will get worse and they believe that a lower power will help.  For the record, there is no evidence that this helps at all – in fact, undercorrecting myopia helps myopia get worse.  Undercorrected children progress faster in their myopia, so our optometrists will ensure that children are prescribed that they need to stabilise and support their visual system.

Simple Advice To Help With Myopia

This is the advice we give to parents about myopia control

  • Encourage your children to spend more time outdoors (with sunscreen of course!)
  • Have regular eye tests and make sure their focusing and teaming skills are checked
  • Don’t under-correct glasses on purpose.  Don’t get them too strong either!
  • Take regular breaks from reading by looking into the distance
  • Limit near work so that it’s less than 2 hours per day (in addition to normal school hours)
  • Understand your treatment options based on the latest research

Do you think your child has Myopia?
Book a check-up with us at your most convenient location.