What is myopia?
Myopia is the medical term for short-sightedness, when the eyeball is too long or too powerful. The result is that light coming into the eye does not focus directly on the retina (the light sensitive layer at the back of the eye), but instead falls in front of it, causing objects in the distance to look blurred. Myopia is traditionally corrected by wearing spectacles or contact lenses. As the eye grows, a person typically becomes more myopic and the power of their spectacle of contact lens prescription increases. Prescriptions over -6DS are considered to be high myopia.
Is myopia becoming more common?
Yes. Myopia is expected to affect 50% of the world population by 2050. In the UK, the amount of myopia has increased from 10% to 23% of children in the past 50 years.
Why do people develop myopia?
Research suggests that a person’s genetics, lifestyle and their day-to-day environment all play a part. People who spend more time doing tasks at a close distance such as working on computers and reading, and those who spend less time outdoors seem more likely to develop myopia. If both parents have myopia then there is a 46% chance that a child will develop it, 31% with one parent and 22% if no parents are myopic. Females have a greater gender tendency for myopia than males.
Does myopia get worse during childhood?
Yes. Generally, once you have myopia your spectacle prescription gets greater over time, in particular during childhood as the eye grows. The key years of change in myopia are between six and 17 years old with the largest change in prescription typically happening at around age seven to eight years and changes getting less as you get older. Generally, myopic children wearing traditional glasses or contact lenses will continue to increase in myopia by approximately 0.50 to 1.00 D (units of measurement) per year. We can use these figures to calculate what we expect a child’s prescription level to be by the time they are in their late teens when change generally starts to slow or stop. Many people develop myopia later in life, however if a child develops myopia, they are at risk of their vision deteriorating much more quickly and for many more years leading to a higher eventual prescription.
Why are higher levels of myopia a problem?
A higher prescription is not only an inconvenience causing poorer vision without glasses or contact lenses but all myopia and especially higher prescriptions (over -6.00DS) are linked to an increased risk of developing eye diseases such as glaucoma, retinal detachment, myopic macular degeneration and cataract in later life. Each dioptre increase in myopia results in 67% increased risk of myopic macular degeneration.
This website My Kid’s Vision is a free online tool that helps parents assess and manage myopia risks for their children. The most accurate assessment will, of course, be performed by your optometrist.
A comprehensive guide to Myopia Management with research on the findings, can be downloaded here – Myopia Management at Cameron Optometry.