Childhood myopia control in Hong Kong: Ortho-K, defocus lenses or atropine?
Why control myopia, rather than just wear glasses?
Myopia is not only about "not seeing clearly". At its core, worsening myopia is the continual growth of axial length (the front-to-back length of the eyeball), and high myopia (generally taken as above -6.00 D, or 600 degrees) markedly increases the adult risk of retinal detachment, macular degeneration, glaucoma and cataract. The goal of myopia control is to slow axial elongation during a child's growing years and lower the chance of these complications later in life.
Hong Kong has one of the highest rates of childhood myopia in the world. During pandemic school closures, local research also found a clear increase in children's myopia and astigmatism, associated with axial elongation¹—outdoor time, working distance and screen habits are all contributing factors.
The three mainstream methods, one by one
1. Orthokeratology (Ortho-K)
Purpose-made rigid gas-permeable contact lenses worn overnight, which temporarily reshape the corneal curvature so the child has clear vision during the day without glasses. A randomised controlled trial at The Hong Kong Polytechnic University (the ROMIO study) showed that Ortho-K can slow axial elongation in children by about 40%³.
- Better suited to: active, sporty children; faster myopia progression; families able to supervise lens cleaning
- Points to note: demands high standards of lens hygiene and regular follow-up to monitor corneal health; not every degree of myopia or corneal shape is suitable
2. Defocus spectacle lenses (such as the DIMS design)
These look just like ordinary glasses: the centre of the lens provides clear vision, while myopic defocus zones are added around the periphery. A two-year randomised controlled trial showed that DIMS lenses can slow myopia progression by about 52% and axial elongation by about 62%².
- Better suited to: younger children not yet ready for contact lenses; families who want to begin myopia control in the simplest way
- Points to note: need to be worn all day to achieve the intended effect; a misaligned frame or scratched lenses will affect the optical performance, so regular checks are needed
3. Low-dose atropine eye drops
Clinical research (such as ATOM2) shows that low-dose atropine can slow myopia progression, with fewer side effects than higher-concentration preparations⁴. In Hong Kong, atropine is a prescription medicine and must be prescribed and monitored by an ophthalmologist; the optometrist can co-manage the examinations and follow-up.
- Better suited to: children who are unsuitable for, or who decline, a lens-based approach; or in combination with optical methods
- Points to note: requires a doctor's prescription; stopping the drops and choosing the concentration need professional follow-up
How much yearly progression warrants intervention?
Generally speaking, if a child's myopia progresses by about 0.75 to 1.00 D (75 to 100 degrees) or more per year, this counts as faster progression and a myopia control plan is worth serious consideration. But a single number is not the whole story—the younger a child is when myopia begins, the higher the risk of developing high myopia later, so children who already have myopia at six to eight years old should be assessed early even if their progression is not yet fast. Changes in axial length reflect what is actually happening better than refractive error alone, which is why axial length is measured at regular follow-up visits.
Three things parents can do right away
- Increase outdoor time: accumulating about two hours of outdoor activity each day helps prevent and slow the development of myopia
- Manage near work: keep reading and screens at about 40 cm, and look into the distance for a rest every 20–30 minutes
- Have regular full assessments: don't wait for the school vision screening to spot a problem—screenings do not measure axial length, nor do they assess binocular visual function
Registered Optometrist (Part I), Hong Kong; BSc (Hons) in Optometry, The Hong Kong Polytechnic University; PhD candidate in Optometry. Seven years of clinical and research experience, focusing on childhood myopia control, binocular vision and vision training. Full professional profile →
- Wong, S.-C., Kee, C.-S., & Leung, T.-W. (2022). High Prevalence of Astigmatism in Children after School Suspension during the COVID-19 Pandemic Is Associated with Axial Elongation. Children, 9(6), 919.
- Lam, C. S. Y., et al. (2020). Defocus Incorporated Multiple Segments (DIMS) spectacle lenses slow myopia progression: a 2-year randomised clinical trial. British Journal of Ophthalmology, 104(3), 363–368.
- Cho, P., & Cheung, S. W. (2012). Retardation of Myopia in Orthokeratology (ROMIO) Study: A 2-Year Randomized Clinical Trial. Investigative Ophthalmology & Visual Science, 53(11), 7077–7085.
- Chia, A., et al. (2012). Atropine for the Treatment of Childhood Myopia: Safety and Efficacy of 0.5%, 0.1%, and 0.01% Doses (ATOM2). Ophthalmology, 119(2), 347–354.