Preventing the Progression of Myopia in Children

By Allison Babiuch, MD

Myopia (nearsightedness) is the most common ocular disorder worldwide, with increasing prevalence over the past decades, especially in East Asia. The World Health Organization estimates that myopia affected 27% and high myopia affected 2.8% of the world population in 2010. It projects the prevalence of myopia to reach 50% by 2050, with as many as 10% being highly myopic.

A major public health concern, myopia poses a heavy health and economic burden to society. In addition to its hindering effects on vision and quality of life, high myopia is associated with an increased risk of serious sight-threatening retinal damage, cataracts and glaucoma.

Several recent studies in the U.S. and other countries have shown a dramatic increase in the prevalence of myopia in schoolchildren.

Numerous interventions to prevent the progression of childhood myopia are being studied. They range from increasing sunlight exposure and limiting near work, to antimuscarinic pharmacological agents, to specialized contact lenses.

Role of environmental and lifestyle factors

Although genetic factors play a role in the development of pediatric myopia, the rapid increase is likely attributable to environmental and lifestyle factors. Environmental causes include less time spent outdoors and more time spent doing near work, such as reading and using computers and mobile devices.

Studies have shown that children who spend more time outdoors have a lower chance of becoming nearsighted. Children from urban environments are more than twice as likely to be myopic as those from rural environments.

It is thought that natural sunlight or sufficient distance-viewing time may provide important cues for eye development. Animal experiments suggest that near work may result in hyperopic defocus of the retina, leading to excessive growth of the eye with resultant myopia.

Atropine drops: What we know and don’t know

Low-dose atropine, a nonselective muscarinic antagonist, is an emerging therapy for myopia progression. However, optimal concentration remains uncertain.

We do not know the exact mechanism by which atropine helps slow myopia progression. Possible mechanisms include:

• Elimination of accommodation.
• Local retinal effects.
• Potential biochemical changes.
• Increased UVA exposure as a result of a dilated pupil, potentially limiting axial lengthening.

Since the prevalence of myopia is much higher in Asia, it is not surprising that the majority of randomized trials in myopia control have been conducted in Asia, including these three:

Atropine in the Treatment of Myopia (ATOM1). The ATOM1 trial found that atropine 1% drops reduced myopia progression and axial elongation. However, atropine 1% commonly results in unwanted side effects, including blurred near vision and photophobia, and has a higher chance of myopic rebound after atropine discontinuation.

Subsequently, lower concentration atropine eye drops were found to slow myopia progression with fewer side effects.

ATOM2. In the ATOM2 trial, 0.5%, 0.1% and 0.01% atropine slowed myopia progression to -0.3±0.60 D, -0.38±0.60 D and -0.49±0.63 D, respectively, over two years. With fewer side effects and less rebound after drop cessation, 0.01% atropine was found to have a better treatment-to-side-effect ratio.

However, this study was limited by lack of a placebo-control group. In addition, axial elongation in the 0.01% group remained significant (0.41±0.32 mm over two years), rendering the role of low-concentration atropine in myopia control uncertain.

In 2017, a report by the American Academy of Ophthalmology concluded that there is level 1 evidence that supports the use of atropine to prevent myopia progression. It stated that given the sustained effect and fewer adverse effects of 0.01% atropine, it may be the most reasonable approach, although the optimal time to initiate and discontinue therapy is not known.

A recent global survey found that nearly two-thirds of pediatric ophthalmology society members regularly prescribe 0.01% atropine to reduce myopia progression.

Low-Concentration Atropine for Myopia (LAMP). Most recently, the LAMP study found that 0.05% atropine (vs. 0.01% and 0.025%) was superior at myopia control. After two years, the mean spherical equivalent progression was 0.55±0.86 D, 0.85±0.73 D and 1.12±0.85 D in the 0.05%, 0.025% and 0.01% atropine groups, respectively. Meanwhile, mean axial length changes over two years were 0.39±0.35 mm, 0.50±0.33 mm and 0.59±0.38 mm, respectively. The most common side effects — loss of accommodation and enlarged pupil size — were mild and well-tolerated in all groups.

The LAMP study contributed to the understanding of low-concentration atropine for myopia control in several aspects. First, it was the first double-blinded, randomized placebo-controlled trial on low-concentration atropine drops, which provides the strongest evidence to support a role in myopia control. Second, it resolved the controversy from the ATOM2 study and delineated a concentration-dependent response in both the efficacy and side-effect profile in atropine concentration ranges from 0.05% to 0.01%. Third, the study further suggested that 0.05% atropine is the most efficacious of the low-concentration atropine levels studied and remains well tolerated.

Several cohort studies on myopia in non-Asian populations have been published. Globally, more than 30 registered clinical trials involving low-dose atropine in concentrations from 0.0005% to 0.05% are ongoing. The future results from these trials should better inform the choice of atropine concentration for myopia control and the issue of rebound with discontinuation.

Specialized contact lenses

Other treatments for myopia are optical methods, including overnight corneal reshaping contact lenses (orthokeratology) and dual-focus daily soft contact lenses.

The Food and Drug Administration recently approved MiSight® contact lenses — single-use, disposable soft contact lenses worn during the day — for children ages 8-12. MiSight has a central zone containing myopic refractive error with concentric peripheral rings of myopic defocus (additional positive power) and distance correction. A three-year randomized controlled trial found that MiSight resulted in a 59% reduction in myopic progression and a 52% reduction in axial length.

Further studies are indicated to assess the safety of children wearing contact lenses long-term as well as rebound myopic progression after discontinuation.

Numerous large-scale studies looking at the causes and treatments of myopia progression are in progress worldwide. Understanding the role of factors influencing the onset and progression of pediatric myopia will facilitate the development of successful treatments and reduction of disease burden.

Dr. Babiuch is a staff member of Cleveland Clinic’s Cole Eye Institute. Her specialty interests include pediatric ophthalmology and adult strabismus.