Recently, a team of researchers at Waterloo’s Centre for Ocular Research and Education found that nearsightedness in Canadian children increases approximately five times from Grade 1 to Grade 8, with roughly a third of the cases going undiagnosed and uncorrected. And though optometrists used to see myopia in children starting around ages 12 and 13, the condition is becoming more prevalent in kids as young as six.[i]
While myopia is usually not a cause for concern, some children ̶ particularly Asian children ̶ experience a rapid progression of the condition. And that’s a serious problem. Because the worse myopia gets, the higher the risk of retinal deterioration, which can lead to vision loss.
In response to growing rates of myopia, the School of Optometry and Vision Science has launched a clinic focused specifically on slowing its progression.
“There’s currently no way to prevent myopia from occurring,” says Dr. Gina Sorbara, head of the School’s Cornea, Contact Lens and Myopia Control Clinic. “Our goal is to catch progressive myopia early, before it reaches the stage where we can’t effect change.”
Genetic and environmental factors
While researchers are not certain what causes myopia, both genetic and environmental factors seem to be at play.
A child’s risk of developing myopia is 26% if one parent is myopic and almost doubles to 45% if both parents have myopia,” Dr. Sorbara says.
Increasing screen time, decreasing outdoor activity and insufficient Vitamin D also appear to be key factors. In fact, the Waterloo study found that reducing screen time and spending one additional hour per week outdoors lowers the odds of children becoming myopic by 14 per cent.
Researchers suspect that sun exposure, which prompts the body to produce Vitamin D and release beneficial chemicals in the retina, is one possible reason for this positive effect. The constriction of the pupil in bright light, resulting in greater depth of focus, could be another.
Slowing the rate of progression
In our clinic, optometrists use the three treatment options shown to be most effective in controlling the progression of myopia: orthokeratology, multi-focal or dual-focus soft contact lenses, and atropine eye drops.
Orthokeratology (Ortho-K) lenses are specially designed rigid lenses that are worn overnight. Multi-focal or dual-focus soft contact lenses are disposable and are worn during the day.
These two types of lenses allow the patient to see clearly. But, as Dr. Sorbara explains, they also create a ring around the centre of the retina where vision is ‘defocused’. Although the patient isn’t aware of this blurred area, the choroid layer of the retina responds to the lack of focus by thickening slightly and thus slowing the growth of the eye.
Low-dose atropine eye drops may be prescribed for children who are unable to wear contact lenses. The drops cause the pupil to dilate and improve focusing ability. However, since there are no studies showing the effect of long-term use, the drops are only prescribed for two years, after which the dose is slowly reduced.
In most children, myopia increases at an average rate of 0.50D per year. While individual results will vary, each of these treatments methods has the potential to reduce the rate of progression by at least 50%, measured using changes in the eye’s axial length, rather than the more subjective refractive error. If you reduce the rate of myopia progression by 50%, the frequency of high myopia decreases by 90%.
Maintaining vision, reducing risk
According to the World Health Organization, myopia could affect one-third of the global population by 2020. And by 2050, researchers estimate that 10% of the world’s population will have high myopia, with its subsequent risks of glaucoma, cataract and retinal detachment.
“By controlling myopia in young children, we can not only help them maintain normal vision now, but reduce their chances of developing eye disease in the future. And that benefits individual kids, their families and our health care system,” Dr. Sorbara says.
The Cornea, Contact Lens and Myopia Control Clinic welcomes new patients as well as referrals for consultation and management of myopia control, keratoconus, presbyopia and astigmatism. Please call us at 519-888-4567, ext. 84414.
[i] Yang, M., Luensmann, D., Fonn, D., Woods, J., Jones ,D. , Gordon, K., Jones, L. Myopia prevalence in Canadian school children: A pilot study Eye 2018;32(6):1042-1047
