Global rise of myopia a mystery
SHORT-SIGHTEDNESS public health problem.
Most people think of myopia (the medical term for short-sightedness) as an inconvenience because the blurred vision it causes is easily corrected with glasses or contact lenses.
The problem is that a myopic eye is a longer eye and so the light-sensitive part at the back of the eye is stretched. This can lead to a number of eye diseases in later life, such as glaucoma, maculopathy and retinal detachment.
Experts are also concerned because the number of people with myopia is increasing. Research suggests that by 2050 it will affect half the world’s population. Myopia normally develops in children and increases in prevalence and amount during the teenage years.
About 30% of teenagers in the United Kingdom have myopia, but in some East Asian countries up to 80% of teenagers have it.
The impact of these levels of myopia on all areas of society is enormous due to the cost of eye examinations, glasses and treatment of eye disease.
The reasons myopia develops are not fully understood. The prevalence has increased too quickly to be explained solely by genetics.
Researchers know that visual environment also has a role in myopia development. Lifestyles have changed significantly over the last 50 years, with much greater time being spent indoors on computers, tablets and smartphones.
It is this lack of time that children spend outdoors that seems to trigger myopia development. At Aston University researchers are looking for ways to prevent myopia, or, if it has started, at ways to slow its progression. is a global
How to reduce the risk of myopia
Spending more time outdoors (at least 90 minutes a day) seems to reduce the risk of developing myopia.
Why this works is not clear. The most recent research suggests that it may be lack of visible violet light indoors that causes the problem, and if we spend time outdoors in daylight we are exposed to ample violet light.
The LEDs and fluorescent lights often used in our homes and schools contain little violet light, and violet light does not pass through materials such as the UV-protected spectacles and the glass in windows.
Specially designed contact lenses can slow the progression of myopia.
If myopia has already developed, then we can slow progression by using different designs of contact lenses or with atropine eye drops.
Atropine eye drops are normally used to temporarily stop the lens inside the eye from focusing and to make the pupil larger.
However, a low dose of atropine eye drops slows myopia progression without affecting pupil size and the ability to focus, though we are not sure why it works.
There are options for soft or rigid designs of contact lenses.
Both types can both correct the blurred distance vision and alter the image in the periphery, and this seems to control the growth of the eye. All these interventions slow the myopia progression by about 50%.
Spending more time outdoors may also help slow down progression of myopia in children.
We do not have all the answers to why and how myopia develops, but we do have ways we can slow down myopic progression.
It is time that we stopped just correcting the blurred vision in myopia and start actively managing and controlling it. — This article first appeared in The Conversation
● Nicola Logan is a senior lecturer in Optometry at Aston University, Birmingham, United Kingdom