Myopia Myths

Below is an article I wrote for an optometry practice (and my current employer) to send to their patients in a quarterly newsletter. With the seemingly relentless spread of short-sightedness around the world I thought I would address some common myths about myopia. The newsletter hasn’t been released yet but you lucky ones get to read the preview! Enjoy. 

Myopia, also known as short-sightedness, is a type of refractive error of the eye that currently affects about 30% of the world’s population1. In Australia, approximately 43% of school children aged 12 are found to be myopic2 with rates even higher in Asian countries; an astounding 97% of 19-year-old South Korean males are found to be short-sighted3. The Brien Holden Vision Institute predicts by that 2050 approximately 5 billion people, half of the world’s projected population, will be short-sighted1. In recent times you may have seen in the media or heard directly from your eye care practitioner about the efforts to address what has been termed the myopia epidemic – so why the hype? It has long been known that myopia is more than a blurry inconvenience; short-sightedness has been associated with other vision-threatening eye diseases such as an increased risk of glaucoma, cataract, and retinal detachment, with higher levels of myopia linked to higher levels of risk.

Both genetic and environmental factors play a role in the development of childhood myopia. It is known that there is a greater likelihood of a child developing myopia if both biological parents are myopic as opposed to one or neither parent being short-sighted4. Research has also been dedicated to looking into the role that the surrounding environment plays in childhood myopia.

In this article we will address some of the common concerns surrounding the development of short-sightedness in children and attempt to separate fact from fiction.

Will increased screen time ruin my child’s eyes?

No. No reliable correlation has been found between the amount of time spent reading or staring at a digital device and the degree of short-sightedness; the findings of multiple studies have been unable to agree on consistently finding an association or no association. What your child may experience with excessive time spent on digital devices is what we call visual asthenopia or digital eye strain. This simply refers to discomfort associated with visual activity and may take on the form of transient blurriness of vision, eye strain, the eyes feeling dry or irritated, headaches, or temporary difficulty focusing on objects further away.

Will wearing spectacles worsen existing myopia?

No. In fact, under-correcting myopia – that is, wearing spectacles of a strength less than what is required for optimal clarity of vision, has been shown to exacerbate the increase of short-sightedness; the greater the degree of under-correction, the greater the myopia progression5. The more immediate consequence is also that the under-corrected short-sighted child is now performing their day-to-day activities, such as copying from the whiteboard at school or learning to drive, with blurry vision and that in itself carries its own unnecessary risks and difficulties. There is no association in regards to any type of refractive error that wearing the appropriate spectacles weakens the eye.

Will reading in the dark cause short-sightedness?

No. Research has not found a link between reading in dim lighting and permanent damage to vision. However, similar to excessive time spent on digital screens, reading a book in poor lighting can contribute to visual asthenopia. In order to read in dim lighting the eye must work harder, which can cause the feeling of tired eyes, headaches, and general eye strain. This is easily rectified by taking a break from reading or improving the lighting conditions but no long-lasting damage is inflicted on the eyes.

What can we do about myopia

Thankfully, a lot of recent research has come to the fore about how both parents and eye care practitioners can address the increasing prevalence of myopia. Here are some options that have been shown to reduce the incidence or myopia or at least slow its progression.

  • Increased time outdoors. Multiple studies have found that children who spend a greater amount of time outdoors were linked to both reduced incidence of myopia and also a significant reduction in the progression of myopia6. The reason for this finding is not yet clear but one hypothesis is that being outdoors with high levels of natural lighting induces the production of the neurotransmitter dopamine, which inhibits physical elongation of the eyeball and the resultant development of short-sightedness. A suggested starting point would be to ensure your child gets at least two hours of time outdoors; this can involve physical activity such as sport or even just reading a book outside. Appropriate UV protection is still recommended, such as sunscreen and sunglasses when in direct sunlight.
  • Contact lenses. Both soft multifocal contact lenses for daytime wear and hard lenses for overnight wear, known as orthokeratology lenses, have been shown to reduce the rate of progression of myopia7, 8. Although some fears may surround the use of contact lenses and children, with appropriate guidance by your optometrist and parental supervision, children can be very successful with contact lens wear.
  • Pharmaceutical eye drops. Atropine eye drops are known to reduce the progression of myopia, and at a low concentration side effects are minimal9. Pharmaceutical eye drops are a good alternative when a child is unable or unwilling to wear contact lenses. While the exact reason behind the effects of atropine is still not fully understood, studies speculate a possible underlying cause is that atropine stimulates the release of dopamine in the eye and inhibits eyeball elongation10, similar to the effect of outdoor time as discussed above.

I recommend your child have their first eye test no later than 5 years of age before they begin primary school, and at least every 2 years thereafter. Eye examinations can help to catch refractive error and visual dysfunctions early and allow these to be addressed before they can interfere with learning during school years. If decreased vision is suspected during maternal health nurse screening then a comprehensive optometry exam is advised earlier. Children at risk of short-sightedness, such as those with myopic parents, should attend regular eye tests. Adults with short-sightedness are also advised to attend for regular optometry appointments due to the increased risk of associated eye disease. For other compelling reasons why you should keep up with your eye tests, read Do I Really Need an Eye Test?

 

References

  1. Holden BA, Fricke TR, Wilson DA, Jong M, Naidoo KS, Sankaridurg P, Wong TY, Naduvilath TJ, Resnikoff S. Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050. Ophthalmology, May 2016. 123(5):1036-1042
  2. Foster PJ, Jiang Y. Epidemiology of Myopia. Eye, Feb 2014, 28(2):202-208
  3. Jung S-k, Lee JH, Kakizaki H, Jee D. Prevalence of myopia and its association with body stature and educational level in 19-year-old male conscripts in Seoul, South Korea. Invest Ophthalmol Vis Sci 2012; 53: 5579-5583
  4. Mutti DO, Mitchell GL, Moeschberger ML, Jones LA, Zadnik K. Parental myopia, near work, school achievement, and children’s refractive error.Invest Ophthalmol Vis Sci. 2002;43 (12:3633–3640.
  5. Vasudevan B, Esposito C, Peterson C, Coronado C, Ciufredda KJ. Under-correction of human myopia – Is it myopigenic?: A retrospective analysis of clinical refraction data. J Optom. Jul 2014; 7(3): 147-152
  6. Sherwin JC, Reacher MH, Keogh RH, Khawaja AP, Mackey DA, Foster PJ. The association between time spent outdoors and myopia in children and adolescents: a systematic review and meta-analysis. Ophthalmology. Oct 2012; 119(10): 2141-51
  7. Walline JJ, Greiner, KL, McVey ME, Jordan-Jones LA. Multifocal Contact Lens Myopia Control. Optometry and Vision Science. Nov 2013. 90(11): 1207-1214
  8. Hirakoa T, Kakita T, Okamoto F, Takahashi H, Oshika T. Long-term effect of overnight orthokeratology on axial length elongation in childhood myopia: a 5-year follow-up study. Invest Ophthalmol Vis Sci. Jun 2012. 53: 3913-3919
  9. Chia A, Chua W-H, Cheung Y-B, Wong W-L, Lingham A, Fong A. Atropine for the Treatment of Childhood Myopia: Safety and Efficacy of 0.5%, 0.1%, and 0.01% Doses (Atropine for the Treatment of Myopia 2). Ophthalmology. Feb 2012. 119(2):347-354
  10. Sander BP, Collins MJ, Read SA. The effect of topical adrenergic and anticholinergic agents on the choroidal thickness of young healthy adults. Exp Eye Res. Nov 2014. 128:181-189

 

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