Two ophthalmologists explain the causes and risks of nearsightedness in children, and how lifestyle changes and treatments can help.
Myopia, also known as nearsightedness, is a condition in which people can see near objects well but have difficulty seeing things far away.
A common condition in urban Asia, Singapore is considered one of the major myopia capitals of world. In fact, not only is the condition considered prevalent with a younger age of onset and greater severity, studies by the National Eye Centre confirm that 10% of Singaporean children will be myopic by age five, increasing up to 60% and 80% by 12 and 18 years old. Plus up to 90% of Singaporean adults (above 18) are projected to by myopic by 2050, with 15% to 25% of these at risk of high myopia.
What causes myopia in children?
Nearsightedness is caused by both genetic and environment factors. If one parent is myopic, there is a 18.2% chance of myopia developing in a child. If both patients are myopic, the risk increases to 32.9%. Children who are born premature and with low birth weight are also at risk of developing myopia.
While myopia is exacerbated by genetic factors, Dr Cheryl Lee, Consultant Ophthalmic Surgeon at The EyeClinic, reveals that most patients now present with myopia caused by environmental factors, including those associated with frequent near work, prolonged exposure to electronic or handheld gaming devices, as well as insufficient exposure to sunlight.
“Genetically-linked myopia presents differently than lifestyle-related myopia where we see very high myopia in two or three years old kids. What is concerning now is that seven to ten year olds have low myopia (any spectacle prescription between -1.00 to -3.00 diopters), which is a problem because barring genetic factors, they should not have myopia at all,” cautions Dr Lee.
Risks of high myopia and how to spot myopia in children
Although many parents may believe low myopia is no big deal, Dr Lee affirms that just as high blood pressure may develop into a stroke, low myopia can progress to high myopia.
According to Dr Cheryl Ngo, Consultant Ophthalmologist & Eye Specialist at the Adult & Eye Specialist (ACE) Clinic, high myopia is defined as nearsightedness of -6 diopters or more and puts patients at risk of multiple disorders later in life, including early cataracts, glaucoma, retinal detachment and macular degeneration that can result in severe vision impairment or even blindness.
To spot early myopia in children, Dr Lee suggests keeping a lookout for signs including: holding a book or handheld device close to the face, sitting close to the TV, squeezing or closing one eye to read, frequent headaches and excessive watering in the eyes.
How myopia progression can be controlled
Myopia occurs because the eyeball is too long. Light rays converge in front of the retina, rather than accurately on it, resulting in difficulty seeing things at a glance. If young patients do not control their myopia, it can worsen as the eyeballs get longer. The good news is lifestyle modifications and treatments can help slow the advancement of this progressive disease.
According to Dr Ngo, one of the simplest ways myopia can be controlled in children is spending more time outdoors as UVB rays stimulate dopamine from the retina, which slows down the growth of the eye. According to a joint report by the World Health Organisation (WHO) and the Brien Holden Vision Institute, children who spend more than two hours a day outdoors have a lower risk of myopia than children who spend less than two hours outdoors, although they have been doing near work or have two myopic parents. Dr Lee, on the other hand, suggests alternating between 20 minutes of near work such as writing, reading, colouring, use of handheld devices as with 20 minutes on something far (beyond arm’s length), for example outdoor activities, or even watching TV from across the room.
As for medical treatments, certain glasses, contact lenses, and eye drops are effective in controlling the progression of myopia and considered safe for children, says Dr Ngo.
“Spectacles are well tolerated among children. However, unlike contact lenses where treatment zones are always in focus, this is not the case for glasses, especially if patients look peripherally.”
There are two types of contact lenses for myopia management in children, the ortho-k overnight lenses, which work by pressing on the cornea and reshaping it during sleep so that children wake up to temporary clear vision during the day, and the daytime multifocal/dual focus contact lenses, which have concentric zones with clear distance, intermediate and near vision, and a peripheral treatment zone to create myopic defocus.
“Although ortho-k lenses offer a 50% reduction of myopia progression in patients, they have a higher risk of infection than day-use lenses and may result in myopia recurrence when patents stop using them,” says Dr Ngo.
“Multifocal/dual focus day time lenses offer long-term control of myopia, as proven by the world’s longest continuous running clinical trial on day-time dual focus lenses. According to the study, children who used these lenses benefited from a slower progression of their nearsightedness than children who used regular contact lenses over a three-year period. The study also showed children who switched to myopia management lenses, after regular contact lenses for three years, enjoyed a slowing of their myopia progression when they used multifocal/dual focus lenses over the next three years.”
Finally, myopia progression can also be treated with atropine eye drops that work by strengthening the collagen polymers in the eyeball. The efficacy of treatment is 30% to 60%, increasing up to 80% with high doses. Nevertheless, the higher the dose, the greater the risk of side effects, including pupil dilation, glare and difficulty focusing on things up close, which is why it’s important for eye care processionals to ascertain the right dose for each patient.
When to intervene and treatments for children
Dr Lee advocates controlling low myopia as soon as it is detected, whether by lifestyle modifications, atropine drops, or myopia management contact lenses or glasses.
“In some cases, it could just be one of these, in others I might recommend a combination of treatments.”
In Dr Ngo’s practice, her first-line treatment for childhood myopia is spectacles because they are safe and well tolerated in children. She generally prescribes day-time multifocal/dual focus lenses to children over eight years old with progressive myopia and who prove to be responsible, have good grooming habits, and are likely to report any lens-related problems to their parents.
Patient compliance and safety
The compliance of the patient is important in myopia treatment, especially with contact lenses, as incorrect use carries a risk of infection, which could lead to complications such as infection and inflammation of the cornea.
In order to reduce the chance of infection, patients should only get a prescription from an accredited eye care professional. Kids should also use contact lenses as prescribed, such as removing them after eight to 10 hours of use, not wearing them during high-risk activities like swimming or while sleeping. If they experience any redness or discharge, they should consult their eye care practitioners immediately.
Children should also practise good hygiene by always washing their hands before and after handling contact lenses, disinfecting them after each use, cleaning and air-drying the storage case daily and not reusing the contact lens solution.
While eye care practitioners spend a long time teaching children these important tips, parents play a vital role in motivating children to practise good eye hygiene and look after their lenses properly, to avoid infection.
“At the end of the day, eye care professionals cannot supervise children at home, so parents must encourage their children to engage in good habits until these become a part of their daily routine,” says Dr Ngo
Main image by Dreamstime.
Doctor photos courtesy of the doctors.
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