Monday August 4, 2008
Accurate prescription
MOST people think shopping for a pair of spectacles is like buying a pair of shoes. However, the process is a lot more complicated and a pair that is not well-made might cause eyestrain or headaches.
“Some parents say, ‘My kids lose their glasses so often I prefer to buy cheap ones’,” says optometrist W.S. Lee. “But I feel you shouldn’t compromise here. There are many grades and different types of lenses, and they play a part in vision care.”
He points out that lenses should be “fundamentally correct”, which means the centre of the glasses should co-relate with the centre of the pupil.
“I had one customer who complained about her glasses despite spending thousands and having seen doctors. After checking, I realised her glasses were fundamentally off by 5mm,” he says.
Kids as young as five sometimes need to wear glasses. As they can be a burden to children, optometrist W.S. Lee suggests that glasses be worn only when needed in class and when watching TV. It’s quite possible to get different results from different optometrists, so how do you decide?
“Go to the one who is interested in you as a person and bothers to explain all the details rather than the one who wants to seal the business deal.”
For the record, an ophthalmologist is a medical doctor with specialist training in eye conditions and treatment, and can prescribe medication and perform eye surgery.
An optometrist, on the other hand, is an eye care professional with a degree in optometry but is not a medical doctor, while an optician (whose main function is to fit and dispense spectacles) usually has a diploma in optometry.
Determining the refraction (“power”) in a child can be tricky, says consultant ophthalmologist Dr Chin Pik Kee. A child below six years old usually needs eyedrops to relax the eye muscles to ensure that the refraction is accurate.
“Since only ophthalmologists are permitted by law to use eye medication, young children usually need to see an ophthalmologist for accurate determination of the refraction. The usual ‘computer eye test’ can be highly inaccurate in children.
“My colleague, Dr Goh Pik Pin, encountered many children with wrong spectacle prescriptions when she and her team did their study.”
When choosing a pair of spectacles, the frame and lenses should be durable, of correct size and fit well. Small frames for very young children are not easily available.
“Of greater concern is the trend of increasing contact lens wear in children. Safe contact wear requires meticulous care and hygiene, which some children may not be mature enough to comply with.
“There is a danger of blinding eye infections (corneal ulcers) with improper contact lens usage. Lack of cleaning (lens and contact lens case), using the wrong or expired cleaning solutions, cleaning with tap water, swimming or sleeping with lenses on – all these are very dangerous,” stresses Dr Chin.
For children with mild refractive error, spectacles can be optional. They should be worn full time if the refractive error is high (above 2.00) and they really can’t see clearly without spectables, or if they are worn to treat other eye conditions such as amblyopia (lazy eye) or strabismus (squint).
“Glasses can be a burden to children, so I tell them to wear glasses only when they need to in class or when watching TV,” says Lee.
Many interventions have been touted to be able to treat refractive error; among pinhole glasses, multifocal spectacles, various eye exercise machines, nutritional supplements, overnight hard contact lens wear and eyedrops.
“Going by strict evidence-based medicine, only one intervention has been shown to have a statistically significant effect on slowing myopia progression, and that is by using a certain eye drop medication,” says Dr Chin.
“There are disadvantages to the medication such as discomfort, sensitivity to light, blurred vision; it is not known if there are any potential long-term risks of extended use on the eye.”
As such, there isn’t any method that has been proven to be safe and effective.
“Parents should bear this in mind before throwing their time and money on such interventions,” she concludes. – By Patsy Kam
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