Myopia Control Beyond Orthokeratology

Part 2 of a three-part series on the art and science of myopia control.

By Sarah Kochik, OD, and Maria Liu, OD, PhD, MPH

Myopia is the most common human eye disorder in the world, with prevalence estimated at nearly 50% in the United States and up to 96% in some Asian countries.1,2 Apart from creating dependence on corrective lenses, myopia is a significant public health concern. High myopia is associated with many sight-threatening ocular pathologies, including retinal detachment, myopic macular degeneration, and earlier onset of cataract and glaucoma.3

TO THE POINT

The second installment of this three-part series looks at multifocal contact lenses and low-concentration atropine as options for myopia control.

Our first article in this series examined the use of orthokeratology lenses in myopia control. In this article, we review two other evidence-based methods of myopia control: multifocal contact lenses and low-concentration atropine.

MULTIFOCAL CONTACT LENSES

As with orthokeratology lenses, the use of distance-center multifocal soft contact lenses has been shown to slow the progression of myopia.4 It has been speculated that both treatments work by presenting two images to the retina: one focused on the retina and one focused anterior to the retina (a myopic defocused image). Myopic defocus has been shown to act as a strong stimulus to slow eye growth in animal studies.

There are three commercially available distance-center multifocal lenses: Proclear multifocal (CooperVision), Biofinity multifocal (CooperVision), and Acuvue Oasys for Presbyopia (Johnson & Johnson Vision Care). Both Proclear and Biofinity lenses utilize an aspheric lens design with full distance correction in the center 2.3 mm of the lens, with progressively more plus extending out to the periphery. The Oasys for Presbyopia lens, on the other hand, uses an alternating ring design, with the full distance correction in the central 2.0 mm of the lens and alternating rings of plus power expanding out to the periphery.

In our experience, most patients find that the aspheric design provides more comfortable vision, but we also have many patients with a strong preference for the alternating ring design. There is no evidence to suggest that either is better in terms of its myopia controlling effect, so we typically leave the decision up to the patient. The patient’s comfort and visual quality will lead to better compliance with treatment.

Unfortunately, there is no daily-disposable distance-center multifocal lens available. However, evidence supports that children can safely wear 2-week or monthly disposable soft contact lenses. A retrospective review of soft lens wearers in US practices showed that children aged 8 to 12 years had the lowest rate of complications among the age groups analyzed.5 In our experience, many children can successfully care for contact lenses independently, and they have the added advantage of parental supervision of their lens hygiene habits. Care instructions are reviewed at every office visit, and an inspection of the lens case is performed. We also find that this is a good opportunity to educate parents (who are often contact lens wearers themselves) on appropriate lens care.

When they first get their lenses, it is not uncommon for patients to experience glare, ghost images, or intermittent blur as they adapt to them. This is especially true when patients are switching from single-vision soft contacts to multifocal lenses. We prepare patients for this in advance, and we rarely make an adjustment to the lenses at the dispensing visit. In our experience, their vision improves with increased lens wear, so that, by their follow-up visit in 1 to 2 weeks, most patients are very comfortable with the lenses and their vision. At this visit, the goal is for patients’ monocular visual acuities to be better than 20/30 and their binocular visual acuity to be 20/20. We then continue to follow them every 4 to 6 months.

Figure. An example of a prescription for 10 mL of preserved, lowconcentration atropine.

ATROPINE

Meta-analyses of myopia control treatment options have concluded that atropine is the most effective treatment available.6,7

Atropine is an irreversible nonselective muscarinic antagonist. It acts by blocking acetylcholine from binding to the muscarinic acetylcholine receptor, known as M3. In the eye, M3 receptors are located primarily in the iris sphincter, where atropine blocks activation of the iris sphincter, causing dilation, and in the ciliary muscle, where atropine blocks activation of the ciliary muscle, causing cycloplegia. Both of these are considered unwanted side effects in myopia control, as topical atropine prevents myopia via a nonaccommodative mechanism.8

There are two competing theories regarding how atropine exerts its myopia controlling effect. The first is that atropine may regulate eye growth by altering retinal neurotransmission due to its effect on muscarinic receptors in the retina.9 The second is that atropine may act directly to strengthen the sclera, as it is now understood that the sclera is biomechanically weaker in myopia.10 This is an area of active research and debate.

The most complete set of clinical data regarding the use of atropine for myopia comes from the collective ATOM studies. In these randomized, double-masked, placebo-controlled trials, 400 children were enrolled in ATOM 1 to test the efficacy of commercially available atropine for myopia control. Participants were randomly assigned to receive either 1% topical atropine treatment or placebo, in one eye only, for a period of 2 years. At the end of the 2-year period, the atropine-treated eyes showed essentially no progression of myopia, while the untreated fellow eyes and the placebo-treated eyes progressed by an average of 1.5 D. However, the study authors noted, 1% topical atropine has limited clinical use due to the severe side effects (dilation and paralysis of accommodation) experienced by the user.11

This motivated a follow-up study, in which the authors attempted to understand the efficacy of different concentrations of atropine while minimizing unwanted side effects. In ATOM 2, 400 children were enrolled and randomly divided into one of three treatment groups in which both eyes were treated with either 0.5%, 0.1% or 0.01% atropine. The 0.01% dose group was intended to serve as a control group, but, much to the authors’ surprise, the 0.01% dose showed significant clinical efficacy for myopia control with minimal change to accommodation and pupil size.12 It was later discovered that, as an added benefit, this group showed no measurable rebound when treatment was discontinued, whereas the higher doses of atropine all showed a significant rebound effect. That is to say, myopia progressed at an even faster rate when higher doses of the drug were discontinued.13

Following the publication of these studies, clinical use of 0.01% atropine sulfate took off. This very low dose has proven to be very safe, tolerable in side effects, and efficacious in halting refractive progression. However, these results should be interpreted with caution. It is believed that the danger of myopia is associated with the excessive axial elongation of the eye. Although ATOM 2 demonstrated a significant reduction in the magnitude of myopia, the 0.01% group showed a much greater increase in axial length during the 2-year study period. This finding of axial length increase without refractive error change continues to puzzle scientists, and it is the subject of ongoing investigation.

Low concentration atropine is not commercially available and must be ordered through a compounding pharmacy. We typically order a 10 mL bottle (Figure), which should last patients about 3 months. You should specify that you would like the medication to contain a preservative. We also perform an in-office demonstration of how to instill eye drops for the patient and parents. We typically see patients about 1 to 2 weeks after they start to use the drops and then every 3 to 4 months thereafter.

OFF-LABEL USES

An important consideration is that all of the treatments discussed above are considered off-label for the purpose of myopia control. No treatment has been approved by the US Food and Drugs administration (FDA) to prevent or slow the progression of myopia. This should not necessarily discourage their use, however; off-label treatments can still be safely and effectively employed in clinical practice, as long as there is thorough evidence to support their use.

This series highlights key findings from the most current literature available. It is important to stay informed and up to date with the contemporary body of knowledge in the practice of myopia control.

In the next and final installment in this series, we will address some of the common questions patients and parents have about myopia control and review some of the literature we use to answer those questions.

Authors’ note: We have an informed consent form that we are happy to make available to readers. This form describes the literature support for these treatments and describes for patients, parents, and guardians what it means for a treatment to be considered off-label.

1. Vitale S, Sperduto RD, Ferris FL 3rd. Increased prevalence of myopia in the United States between 1971-1972 and 1999-2004. Arch Ophthalmol. 2009;127(12):1632-1639.

2. Pan CW, Dirani M, Cheng CY, et al. The age-specific prevalence of myopia in Asia: a meta-analysis. Optom Vis Sci. 2015;92(3):258-266.

3. Flitcroft DI. The complex interactions of retinal, optical and environmental factors in myopia aetiology. Prog Retin Eye Res. 2012;31(6):622-660.

4. Walline JJ, Greiner KL, McVey ME, Jones-Jordan LA. Multifocal contact lens myopia control. Optom Vis Sci. 2013;90(11):1207-1214.

5. Chalmers RL, Keay L, Long B, et al. Risk factors for contact lens complications in US clinical practices. Optom Vis Sci. 2010;87(10):725-735.

6. Huang J, Wen D, Wang Q, et al. Efficacy comparison of 16 interventions for myopia control in children: a network meta-analysis. Ophthalmology. 2016;123(4):697-708.

7. Walline JJ, Lindsley K, Vedula SS, et al. Interventions to slow progression of myopia in children. Cochrane Database Syst Rev. 2008;(12):CD004916.

8. McBrien NA, Stell WK, Carr B. How does atropine exert its anti-myopia effects? Ophthalmic Physiol Opt. 2013;33(3):373-378.

9. Harper AR, Summers JA. The dynamic sclera: extracellular matrix remodeling in normal ocular growth and myopia development. Exp Eye Res. 2015;133:100-111

10. McBrien NA, Jobling AI, Gentle A. Biomechanics of the sclera in myopia: extracellular and cellular factors. Optom Vis Sci. 2009;86:E23-30.

11. Chua WH, Balakrishnan V, Chan YH, et al. Atropine for the treatment of childhood myopia. Ophthalmology. 2006;113(12):2285-2291.

12. Chia A, Chua WH, Cheung YB, et al. Atropine for the treatment of childhood myopia: safety and efficacy of 0.5%, 0.1%, and 0.01% doses (Atropine for the Treatment of Myopia 2). Ophthalmology. 2012;119(2):347-354.

13. Chia A, Lu QS, Tan D. Five-year clinical trial on atropine for the treatment of myopia 2: myopia control with atropine 0.01% eyedrops. Ophthalmology. 2016;123(2):391-399.

Sarah Kochik, OD, FAAO
• clinical instructor and PhD candidate, University of California, Berkeley, School of Optometry
• financial interest: conference travel support, Paragon Vision Sciences
skochik@berkeley.edu

Maria Liu, OD, PhD, MPH, FAAO
• assistant professor, clinical optometry and vision science, University of California, Berkeley, School of Optometry
• financial interest: consultant, Paragon Vision Sciences
marialiu@berkeley.edu