Why Myopia Matters: 5 Things to Know

Brianne N. Hobbs, OD

Disclosures

July 11, 2019

Three Things To Do

1. Encourage children to spend time outdoors.

Time spent outdoors protects against the development of myopia.[9,10] What the child is doing outdoors matter much less than simply being outdoors.[11]

It is plausible that time outdoors is protective simply because it means less time doing near work, such as reading on a device. However, researchers have demonstrated that the benefit of outdoor time persists independent of time spent reading.[12]

Outdoor time seems to be most beneficial in preventing myopia from developing in the first place rather than slowing its progression. Myopia is typically diagnosed between the ages of 8 and 12 years, so the most critical time is in children younger than 8 years; but, for myriad reasons, it is never too early to encourage outdoor play.

The amount of time outdoors needed to achieve this positive effect has not been clearly defined. One major study[9] found that 14 hours per week outdoors reduced the incidence of myopia by two thirds—from 60% to 20% in children who had a genetic risk for myopia. In another study,[10] researchers examined the incidence of new cases of myopia in children in one school where time outdoors was increased by 80 minutes per day compared with another school where children spent their recess period in the classroom. New cases of myopia were reduced by approximately 50% over a 1-year period in children who spent recess outdoors.

The physiologic process by which sunlight affects myopia development is unclear. One hypothesis is that sunlight prompts the release of dopamine in the retina that normalizes the accelerated growth rate of a myopic eye. This hypothesis is supported by seasonal differences in the rates of myopic progression, which are slowest in the summer.[13]

2. Recommend limited use of digital devices, especially for younger children.

The use of digital devices and their potential effects on myopia development is an area of great concern. The introduction of digital devices to children at increasingly younger ages may have some effects on the developing visual system, but those potential consequences are not fully known.

One study[14] found that the majority of 2-year-old children used mobile devices daily and that 92.2% of 1-year-old children had used a mobile device, so exposure is widespread even though the impact is yet to be determined.

Myopia is thought to be caused by a combination of genetic and environmental influences. Although the amount of near work, a modifiable environmental factor, has specifically been implicated in the development of myopia, the evidence is mixed.[9,15,16,17] The use of digital devices would represent a specialized type of near work, so it may ultimately be found to be a risk factor for the development of myopia. However, it is too soon to tell.

3. Ensure that myopia is corrected completely.

Undercorrection, thought to be beneficial by some, actually accelerates myopia progression.[18] Several optical and pharmaceutical options work to slow the progression of myopia rather than simply neutralize its effects.

Low-dose atropine has been shown to dramatically reduce myopia progression, but the optimal duration of treatment has not been determined.[19] There are also concerns about the potential long-term adverse effects of atropine. Atropine causes pupil dilation and blurred near vision, and although these effects are minimized at low doses, they can still be problematic.

Orthokeratology, an optical method to slow myopia progression, involves wearing gas permeable contact lenses overnight that flatten the cornea, thereby reducing the overall power of the eye. In addition to contact lenses, another option is bifocal glasses.

An emerging possibility for the therapeutic control of myopia, 7-methlyxanthine, is being studied in Denmark. 7-methylaxanthine affects the release of neurotransmitters, including dopamine. An initial report[20] shows that it substantially reduces myopia progression and excessive eye elongation. Further studies are needed to establish its safety.

In a recent comprehensive report, the Interventions Myopia Institute[21] concluded that although promising treatments are being investigated, currently there is no single treatment that has been found to be effective in preventing or slowing myopia progression in all children. But in the interim, these three recommendations are evidence-based and may provide substantial benefits.

Follow Medscape on Facebook, Twitter, Instagram, and YouTube

Comments

3090D553-9492-4563-8681-AD288FA52ACE
Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as:

processing....