Myopia, and what is it?

2014_11-children-wearing-glasses

An Asian family of four comes into our clinic for an eye check-up for their eight-year-old son. I can see he is already squinting his eyes, but I am unsure whether or not it is because his glasses are quite oily. I usually ask him if he notices any changes, whether he can see the board at school, any troubles doing sports and so forth. In this case, the boy mutters there has been no change. However, when the chart flicks on, he completely misreads all the letters. By this stage, both parents are frowning while the younger child sitting across the room is laughing at the brother. By the end of the examination, the older brother has had a prescription increase and requires stronger glasses to help him see the board. Sadly, this is an increasing occurrence in both young children, teenagers, and young adults.

Myopia or short-sightedness and near-sightedness is a vision disorder where objects and things are blurry unless they are placed close to the person. The poor distance vision is due to the eye being too long for light to be focused on the retina. The image is focussed in front of the retina, therefore, appear blurry.

myopic-eye-diagram

The distance of clear vision depends on the degree of myopia. A higher prescription usually means the person is more short-sighted and require the object to be closer to focus properly. The best way to manage short-sightedness is to prescription glasses or contact lenses to allow the child to focus at school.

Myopia is one of the most researched eye conditions due to its growing prevalence. It is estimated that 90% of children have myopia in the East-Asian regionswhilst this contributes to 3.9 and 7.2 billion US dollars in correcting the affected patients in the United States2. Genetic factors play a role in myopia development and progression. However, environmental factors also contribute to its progression with a strong correlation between near work, education and diet and diabetes with myopia, whilst physical activities and outdoor activities had less myopic association3. Occupational myopia is also seen in today’s work-force with increased demands in sustained near work, frequent changes in focusing, and the need for accurate focusing in fine print3.

Prevention options

A look at many studies has found increased outdoor activities to have protective mechanisms against myopia. An extra 1.25 hours a day in outdoor exposure can reduce the risk of onset by 50%4.

Other effective and prevention options for myopia progressions include the use of orthokeratology, an overnight rigid lens to correct both short-sightedness and its progression, pharmaceutical eye drops to control retinal growth, soft multifocal contact lenses5, Zeiss Myovision™ lenses. It is important to talk to your local optometrist to assess which treatment option is most suitable for your child.

Consequences of myopia progression

Unfortunately, with increasing myopia, both child and adult are at a greater risk of cataracts, glaucoma, retinal detachment, and myopic maculopathy. An increase in 1 dioptre from normal would double the risk of cataract development, quadruple the risk of glaucoma, triple the risk of retinal detachment and double the risk of maculopathy. This risk increases almost exponentially as the degree of myopia rises.

It is still best to seek the advice of your local optometrist for the best advice and management.

References:

  1. Theophanous, C., Modjtahedi, B. S., Batech, M., Marlin, D. S., Luong, T. Q., & Fong, D. S. (2018). Myopia prevalence and risk factors in children. Clinical ophthalmology (Auckland, N.Z.)12, 1581-1587. doi:10.2147/OPTH.S164641
  2. Pan C‐W, Ramamurthy D & Saw S‐M. Worldwide prevalence and risk factors for myopia. Ophthalmic Physiol Opt2012, 32, 3‐16. doi: 10.1111/j.1475‐1313.2011.00884.x
  3. Goldschmidt, E., & Jacobsen, N. (2013). Genetic and environmental effects on myopia development and progression. Eye (London, England)28(2), 126-33.
  4. Xiong, S., Sankaridurg, P., Naduvilath, T., Zang, J., Zou, H., Zhu, J., … Xu, X. (2017). Time spent in outdoor activities in relation to myopia prevention and control: a meta-analysis and systematic review. Acta Ophthalmologica, (6), 551. https://doi-org.ezp.lib.unimelb.edu.au/10.1111/aos.13403
  5. Lagrèze, W. A., & Schaeffel, F. (2017). Preventing Myopia. Deutsches Arzteblatt international114(35-36), 575-580.