Both glasses and contact lenses have been used to correct myopia in children, but which is more effective in managing the condition in the long run?
Myopia, or nearsightedness, is a growing epidemic in the Asia Pacific. High myopia is a leading cause of visual impairment and blindness in some Asian countries and can lead to serious vision disorders such as myopic macular degeneration, retinal detachment, glaucoma, and cataract.
This sight-threatening condition occurs due to the abnormal elongation of the eyeball, causing the light to focus in front of the retina rather than directly on it. As a result, people with myopia can see objects that are up close but struggle to see things at a distance.
Untreated myopia does not just go away or get better over time. In fact, the earlier myopia sets in the faster its rate of progression. However, experts believe early detection and intervention can slow down the progression of myopia in children.
Conventional single-vision glasses
Spectacles, or glasses, have long been the go-to treatment for children with myopia. When a child’s myopia is first detected, single-vision glasses are typically prescribed to correct their blurred vision when looking at things from a distance. However, numerous studies show they have little impact in controlling or slowing down the progression of myopia.
“Single-vision glasses work by refocusing the light entering the eye, enabling clear vision. However, this is simply a band-aid solution and does not actually address the underlying condition, which is the abnormal elongation of the eyeball. To continue enjoying clear vision, children using single-vision glasses have to periodically increase the prescription of their glasses, as their myopia progresses,” says Dr Cheryl Ngo, Consultant Opthalmologist & Eye Specialist at the Adult & Eye Specialist (ACE) Clinic.
A common fallacy in some Asian countries is that stronger prescriptions will make the child’s eye-sight worse. As a result, a myopic child may be prescribed with under-powered single vision glasses, which not only do not correct the condition but can actually speed up the progression of childhood myopia.
Spectacles targeted for myopia control
There are varying types of spectacles targeted for myopia control, with varying degrees of efficacy: progressive lenses (0-10%), bifocals (0-20%), and peripheral defocus glasses (50%).
These options are superior alternatives to single-vision glasses when it comes to myopia control. They are usually prescribed to patients whose parents are not open to them using contact lenses, especially when cost is a concern.
“While glasses are better tolerated and accepted by both children and parents, they tend to be less effective in controlling myopia than contact lenses. Some children may feel more self-conscious wearing glasses, and wearing glasses on days when they are playing sports can be inconvenient if not impractical,” says Paul Lau, Registered Optometrist, Children’s Eye Care Centre (Hong Kong).
Contact lenses for myopia control
There are two major types of contact lens for controlling eye growth in children, the ortho-K overnight lenses and daily disposable dual focus lenses.
Orthokeratology (ortho-k) lenses are hard contact lenses that work by pressing on the cornea and reshaping it during sleep so that children can wake up to temporary clear vision the next day without the use of a visual aid. A five-year investigation revealed ortho-k lenses offered a 50% reduction of myopia progression in patients.
On the other hand, daily disposable lenses such as dual focus contact lenses, are soft contact lenses that allow the wearer to enjoy clear vision while the lenses are in use.
Recent findings indicate that dual focus contact lenses can offer significant benefits in terms of myopia control, as it is able to reduce eyeball elongation in children with myopia. This slows myopia progression in the child, in addition to providing clear vision.
“An advantage of contact lenses over spectacles is that its treatment zones are always in focus. This means the child can enjoy clear vision whichever way they look. With most spectacles, the wearer has to focus in a specific direction in order for them to be effective, which can be a challenge for younger children,” says Woon Pak Seong, optometrist and managing director of Vision Space (Malaysia).
While both ortho-k and dual focus contact lenses have been found to be effective in controlling myopia progression, ortho-k lenses have been associated with a higher risk of infection as it they require more cleaning. Myopia can also recur when the patient stops using them.
Are contact lenses safe?
While many parents are concerned about the safety of contact lenses for children, experts say that complications arising from contact lens usage in children is very minimal as long as they care for them in the recommended way.
“Contact lenses can be fitted in young children even at five or six years old. They are generally safe, provided patients can adhere to the necessary protocols in caring for their lenses such as washing hands before and after fitting the lenses, changing the lens solution, and so on,” says Lau.
However, contact lenses are not risk-free. Less severe complications include dry eyes, abrasions, allergic reactions, and droopy lids from excessive tugging of the upper lid. Although eye infections are a risk, they tend to occur when the wearer does not follow the recommended protocols.
Ultimately, patient selection is key when prescribing any form of treatment for myopia.
“Eye care practitioners may sometimes combine one or more treatment approaches to suit the needs, preferences, lifestyle, and comfort level of the patient. It’s important to discuss the different treatment options with the young patient and his or her parents, before recommending a course of action with the aim of controlling or slowing down their myopia progression,” says Woon.