Why Myopic Children need to have a Functional Vision Assessment — Interview with Dr Yap Tiong Peng (IGARD Vision Therapy Singapore)
Myopia is not simply about wearing spectacles but to prevent and control the progression of myopia. While getting a paediatric eye examination is often the first thing to do, some children may benefit in getting a Functional Vision Assessment. This is essentially a more detailed assessment of the child’s eye focusing and eye alignment skills.
Here are 3 good reasons for you to do so:
- 1. Functional Vision Assessment can help us to identity the children at risk of myopia
- 2. Functional Vision Assessment can help to determine if your child would respond to spectacle lens treatment.
- 3. Functional Vision Assessment can help you to make the right choices in your child’s journey in myopia control
While genes are often blamed as the cause of myopia, there are many other non-genetic factors that cause myopia. To help parents in identifying whether a child is at risk of myopia, IGARD recommends a paediatric eye examination at the age of 4-5 years and decide later on if a pre-myopic child has to come for a Functional Vision Assessment.
Research has shown that myopic children tends to have some mild but significant issues in terms of their eye focusing skills and these issues can even be detected before they start wearing spectacles! “In medical terms, we call this accommodative lag and esophoria but its level or magnitude usually does not cause any discomfort or symptoms”, said Dr Yap Tiong Peng who heads the IGARD Vision Therapy Centre in Singapore.
“We tend to find these issues in pre-myopic and myopic children and it is possible to help some children before the onset of myopia”, said Dr Yap. For example, one study found nearly 20 times greater risk of myopia development within one year when these issues are present (See: Mutti, Jones, Moeschberger, Zadnik. AC/A Ratio, Age, and Refractive Error in Children. Invest Ophthalmol Vis Sci 2000;41:2469-2473).
Quoting another study, Dr Yap said, “There are also more serious situations, where up to 50% of children with intermittent exotropia become myopic by the age of 10 years and nearly 90% are already myopic by adulthood” (See: Ekdawi, Nusz, Diehl, Mohney. The development of myopia among children with intermittent exotropia. Am J Ophthalmol. 2010; 149(3):503-7).
It would be most straightforward for myopic children to wear spectacles, but there are many lens types and choices to make. While some spectacle lens companies does very well in marketing or promoting the products to consumers, how do we know which lens type is best for the child? Dr Yap says, “It is true that some spectacle lenses tends to perform better than others, but you’ll also need to find out what might works best for your child as an individual”.
Dr Yap recommends parents to seek professional advice from an optometrist and a Functional Vision Assessment can help to guide clinical decision-making. “Some children are expected to respond better to a certain type of spectacle lens treatment”, said Dr Yap. Citing progressive addition lenses (PAL) as an example, Dr Yap said, “Treatment effects could be more efficacious in children with larger magnitudes of accommodative lags”.
He added, “There are also situations that you’d just not prescribe PALs because there might be better spectacle lens options (for myopia control), so it’s important to discuss this with an optometrist who understands the science behind lens prescribing in children.” (See: Gwiazda, Hyman, Hussein M et al. A randomized clinical trial of progressive addition lenses versus single vision lenses on the progression of myopia in children. Invest Ophthalmol Vis Sci 2003;44:1492-1500).
“There are many spectacle lens options that seems promising in children myopia control, so please explore those options with your optometrist.” (See: Lam, Tang, Tse, et al. Defocus Incorporated Multiple Segments spectacle lenses slow myopia progression: a 2-year randomised clinical trial. Br J Ophthalmol. 2020; 104(3):363-368; Bao, Yang, Huang, et al. One-year myopia control efficacy of spectacle lenses with aspherical lenslets. Br J Ophthalmol. 2021:318367).
Orthokeratology and atropine therapy are often touted to be the most efficacious approach in children myopia management, but these are huge decisions for parents and it’s important to make an informed decision.
“Functional Vision Assessment can help to guide clinical decision-making”, said Dr Yap; and either approach can work in most children. But Dr Yap pointed out, “It’s a red flag if myopia is still increasing and it would make sense to attend a Functional Vision Assessment to find out what’s going on”. If there are abnormalities during this detailed assessment, it’s likely that a different strategy may be necessary for myopia control and there may often be other important challenges that may need to be addressed, such as vision-related learning challenges.
Dr Yap suggests a cautious approach in monitoring myopia progression so that you can keep track of the efficacy of these treatments or therapies. “If you have a Functional Vision Assessment, you’ll be able to consider the eye focusing and eye alignment skills in relation to the rest of the clinical findings”, said Dr Yap. “Do not simply increase the treatment dosage if myopia is increasing rapidly, because there may be other functional vision issues that need further investigation”.
Current scientific evidence seems to show good results in functional vision during orthokeratology treatment. “If you’re looking at orthokeratology treatment, there’s a two year study which showed that children with lower accommodative amplitude could achieve 56% better myopia control than children who have higher accommodative amplitudes” (See: Zhu, Feng, Zhu, Qu. The impact of amplitude of accommodation on controlling the development of myopia in orthokeratology. Chin J Ophthalmol 2014;50:14-19).
“While some patients should explore vision therapy to remediate the functional visual deficits, there are some studies that found that orthokeratology treatment can be beneficial in improving certain functional vision issues, such as esophoria and accommodative lag”, said Dr Yap (See: Gifford, Gifford, Hendicott, Schmid. Zone of Clear Single Binocular Vision in Myopic Orthokeratology. Eye Contact Lens. 2020;46(2):82-90).