Health Sense: How do I know if my child has myopia?
Does your child often strain to look at things around him?
If yes, then your child could possibly be suffering from myopia, or short-sightedness. Myopia in Singapore is extremely common. In fact, the sunny island has one of the highest rates of childhood myopia.
Most people call myopia “shortsightedness”. What exactly is myopia?
What most laymen term “myopia” or “shortsightedness” is a condition where the eyeball is longer than normal. That is to say, light rays from distant objects are focused in front of the retina, rather than on the retina, thus resulting in a blurry image. In this condition, objects a short distance away are seen more clearly as the image is focused nearer to the retina, hence, the term – “shortsightedness”.
What are the primary causes of myopia?
The exact cause is not known for sure. The current perception is that myopia occurs because of environmental factors acting on genetically predisposed eyes.
Evidence for environmental factors:
• Studies in Hong Kong, Xiamen and Singapore have shown that children who spend most of their time reading and writing in primary school have a higher incidence of myopia.
• Myopia became more common among Eskimo children after the introduction of Western education.
• Premature children with low birth weight tend to have higher incidences of myopia.
• Myopia can be induced in various animals such as monkeys, chickens and tree shrews by degrading the image seen in the eye e.g. putting a translucent occluder over the eye.
• Children with glaucoma and uncontrolled eyeball pressure develop myopia.
Evidence for genetic factors:
• Closer degrees of myopia in identical twins compared to fraternal twins.
• Severe myopia often runs in families.
• Chances of myopia in children are higher if both parents are myopic compared to if only one parent suffers from the condition.
• More common in Chinese, less common in Afro-Carribeans.
• Some genetic diseases are associated with myopia.
It seems to be very prevalent amongst young children. Is there a reason why?
It is not very prevalent in young children compared to older children. However, its prevalence in younger children may be rising possibly due to increased amounts of “nearwork” activity that young children indulge in these days, such as computer/handheld games or schoolwork.
At what age does it begin?
It can begin at any age, even in infants. It usually begins at school-going age.
How do I know if my child has myopia?
Symptoms of myopia in children include:
• Straining/squinting the eyes to look at far objects.
• Holding things close to the eye.
• Turning the face sideways to look at objects.
• Cannot see writing on a whiteboard.
Does it get worse over time? Can its progression be controlled?
In children, it tends to increase in power or worsen till the child is in his teenage years.
Can myopia be cured completely?
No. Myopia is in vast majority of cases due to an eyeball that is too long. This structural abnormality cannot be corrected by any means with current knowledge. Simply put, a long eyeball cannot be made to shrink to normal size.
What are the current treatment methods available for myopia?
Myopia can be corrected with spectacles (safest method), contact lenses or refractive surgery (surgery only meant for adults with stable myopia).
Refractive surgery reshapes the normal front part of the eye (cornea) so that light rays are focused on the retina, but it does not cure the underlying problem, which is an eyeball that is too long.
After surgery, the eyeball is still long and potential problems with myopia (e.g. macular degeneration, retinal tear or detachment) are still present. Another surgical method for very high degrees of myopia is to implant intraocular lenses within the eye to correct the myopia.
This involves surgery inside the eye with its attendant risk of inflammation inside the eye, eye infection and damage to internal eye structures.
A lens implant is not recommended for most patients. To prevent myopia from worsening or to slow down the increase in myopia, the only evidence-based medical treatment to date that is shown to be effective is the use of atropine eye-drops or pirenzepine eye gel.
Atropine eye-drops are effective in about 70 percent of children. Pirenzepine is less effective and is not commercially available.
Atropine eye-drops have side effects such as blurring of near vision and light sensitivity (due to dilation of the pupil), which may require the use of photochromatic glasses.
The eye-drops must also be used daily for years. The long term side-effects of atropine treatment in children are not completely known.
The eye-drops are thus recommended only for children with rapidly progressing or high degrees of myopia.
There is no good scientific evidence that progressive addition (multifocal) glasses, bifocal glasses, under-corrected glasses or contact lenses are effective in preventing myopia progression.
How can myopia be prevented?
Until today there is no proven method to prevent myopia. Possible preventive measures include:
• Ensure good lighting when doing “nearwork”.
• Take vision breaks of 5-10 minutes after every 30-45 minutes of work.
• Hold reading/writing material at a minimum of 1 foot away from eyes.
• Sit about 50 centimeters from the computer.
• Do not read lying down.
• Go to sleep early.
• Engage in healthy, daily outdoor activities.
• Avoid reading materials with small font or faded print, as more effort is needed to focus on the words, resulting in eyestrain.
Selected comments will be published in the Readers’ Forum page of our print newspaper.