TheConversation: Short-sightedness is a global 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. We know that about 30% of teenagers in the UK have myopia, and in some East Asian countries around 80% of teenagers have myopia.
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 why myopia develops are not fully understood;
the prevalence has increased too quickly to be explained solely by
genetics.
We know that our visual environment
also has a role in myopia development. Our lifestyle has changed
significantly over the last 50 years, with greater time being spent
indoors on computers, tablets and smartphones.
It is the lack of time that children spend outdoors that seems to
trigger myopia development. At Aston University, we are looking for ways
to prevent myopia, or, if it has started, at ways to slow its
progression.
How to reduce the risk of myopia
We know that spending greater time outdoors
(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 the 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.Sergei Domashenko/Shutterstock.com
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. A low dose of
atropine eye drops also 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, and
both types as well as correcting the blurred distance vision also 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
stop just correcting the blurred vision in myopia and start actively
managing and controlling it.