Parents play a vital role in protecting their child's eyesight. Understand genetic and environmental risk factors. Correct vision and control abnormal eye elongation to prevent long-term vision-threatening complications.
Managing myopia is more than just vision correction. As parents of children with myopia, you have a vital role to play in safeguarding their eyesight and ensuring their long-term visual health.
With an estimated 2.6 billion people worldwide affected by myopia in 2020, and its prevalence projected to reach approximately 4.8 billion, or 49.8% of the word population, by 2050,1 understanding this condition is more important than ever.
Myopia is influenced by a combination of genetic and environmental factors, making it essential to consider both aspects when managing the condition. The goal is to not only correct vision but also tackle the abnormal elongation of the eye, which contributes to myopia progression.2 Fortunately, there are various treatments and healthy eye habits that can have a positive impact and may slow down the progression of myopia.
In this article, we will explore these considerations and provide you with an overview of why managing myopia is more than vision correction. So, let's dive right in and discover the world of myopia management.
Understanding myopia: blurry vision and abnormal eye elongation
Myopia, also known as nearsightedness, is a prevalent vision condition that affects children's ability to see distant objects clearly. While they may have no trouble seeing objects up close, things in the distance may appear blurry.
The primary cause of this blurriness lies in the way light enters the eye and focuses on the retina. In a normal eye, light rays pass through the cornea and lens and precisely focus on the retina, the light-sensitive tissue at the back of the eye.
However, in children with myopia, the eye becomes abnormally elongated, causing the light rays to focus in front of the retina instead of directly on it. When light fails to focus correctly on the retina, the signals sent to the brain by the photoreceptor cells become distorted, resulting in blurry vision.3
To address myopia, it is important to both improve the clarity of vision and prevent further elongation of the eye.
Is myopia determined by genetics or environmental factors?
Is myopia a result of genetics or the environment? This question has puzzled researchers and parents of children with myopia alike. What we have learned is myopia is influenced by a combination of genetic and environmental factors, particularly the lifestyle and habits of school-going children.
Heredity and genetics-related risk factors
Studies have shown that myopia has a strong hereditary component. While the exact heritability estimates may vary, they are generally high. When researchers used a genetic risk score for myopia to help determine how likely someone is to have myopia based on their genes. What they've discovered is that individuals with a high genetic risk have a much greater chance (up to 40 times higher) of developing myopia compared to those with a low genetic risk.4
Ethnicity: Ethnicity plays a role in myopic progression, with Asian populations having higher prevalence and incidence rates compared to European Caucasians. African-Americans tend to have the least progression of myopia. These variations highlight the impact of ethnicity on myopia development.5
Parental Myopia: Having one myopic parent increases the risk of myopia in childhood while having both parents with myopia multiplies the risk. Research indicated that if you have myopia, your kid's chance of having myopia is 1.5 to 2.1 times higher. If both parents have myopia, the likelihood increases to up to 3.0 times. And parental myopia not only increases the chances of developing myopia in children but also contributes to its progression.6
Environmental risk factors
While myopia often has a genetic basis and tends to be hereditary, it can also manifest in children whose parents do not have the condition. The development of myopia is influenced by environmental risk factors. Moreover, research indicates that environmental factors have played a significant role in the increasing prevalence of myopia over the past few decades.4
Outdoor Time: Spending more time outdoors has been consistently linked to a reduced risk of myopia onset. The exact mechanisms behind this protective effect are still being explored, but the time spent outdoors itself seems to be the key factor.7
Near Work: Engaging in extensive near work activities, such as reading or studying, is associated with a higher risk of developing myopia. Increased time spent within a close working distance also poses a risk for myopia.3
Understanding the interplay between genetics and environmental factors is crucial in comprehending the development and progression of myopia. While genetic predisposition plays a role in myopia, it is essential to consider other factors that can contribute to its occurrence in children, even if their parents do not have myopia.
Understanding the link between the growth of the eyes and myopia
To begin, it is important to understand the concept of emmetropization. Emmetropization refers to the natural process during postnatal development where the refractive components and axial length of the eye come into balance. In other words, as your body naturally emmetropizes, your eye grows and becomes without any refractive error. It is worth noting that most infants initially have hyperopia (farsightedness) and gradually reach emmetropia.2
In children without myopia, their eyes are expected to undergo normal growth from birth until around the age of 12. During the school-aged years, the eye grows at a rate of about 0.1 to 0.2 millimeters per year. As children enter their teenage years, this growth slows down to around 0.1 millimeters per year and eventually stops in the early teens.8
In myopia, the condition develops during the school years and continues to progress into adulthood, although it can also develop in adults. The progression of myopia generally slows down during the teenage years, but in some cases, it may continue into the 30s. Studies have shown that the annual progression of myopia is approximately -0.50 diopters in Caucasian children aged 8 to 12, while it is twice as fast for Asian children in the same age range.9
Furthermore, eye growth starts to accelerate in the year before the child becomes nearsighted. This accelerated growth can reach approximately 0.2 millimeters per year. Once myopia is present, the accelerated eye growth continues at a rate of more than 0.3 millimeters per year until the child reaches the age of 10 or 11. After age 12, children and teenagers with progressive myopia still experience some eye growth, but at a slower rate of around 0.2 millimeters per year.10
It is important to note that the earlier a child develops myopia, the more years their myopia may progress, and their eye axial length may continue to grow. Having myopia at a younger age increases the likelihood of ending up with more severe myopia, which is associated with a higher risk of eye diseases and vision impairment in adulthood.2,3
Research has shown that more severe myopia is linked to an increased risk of eye diseases and vision impairment later in life. For instance, if the eye grows to more than 26 millimeters, there is a significant increase in the risk of eye problems during adulthood. If the eye grows to more than 30 millimeters, there is a staggering 90% chance that the person will experience vision impairment in their lifetime.11
Clear vision and eye axial length control in myopia management
When it comes to managing myopia in children, there are two main goals that parents should keep in mind. The first goal is to correct their child's vision and help them see clearly. This is typically achieved through corrective lenses, such as glasses or contact lenses. By focusing light directly onto the retina, these lenses improve vision and make daily activities easier for children with myopia. And the second goal is to slow down the abnormal eye elongation.2,3
Correcting vision alone is not likely to help address the underlying issue of abnormal eye growth associated with myopia in children. Further, it is important to be aware that the vision-threatening complications of myopia are closely linked to the elongation of the eyeball.2
For example, abnormal eye elongation is associated to the thinning and stretching of the retina. This may increase the chances of retina tears or even retinal detachment, both of which can severely impair vision. Moreover, the elongation of the eyeball may trigger the overproduction of vascular endothelial growth factor, which could cause abnormal blood vessel growth in the macula, leading to a condition called myopic macular degeneration.12
Furthermore, structural changes to the optic disc in the eye may occur due to the elongation, which can damage nerve cells and contribute to the development of glaucoma.13 Nutrient delivery to the eye may also be affected by the elongation, which can result in inadequate nourishment and the accumulation of biochemical by-products. In some cases, this may even lead to the formation of cataracts.2
A recent review study also revealed that individuals with myopia are 100 times more likely to develop myopic macular degeneration (MMD), have a three-fold higher risk of retinal detachment or cataracts, and have nearly twice the risk of glaucoma. Additionally, the severity of myopia – the higher the refractive errors -- is directly correlated with the likelihood of experiencing these complications.14
Therefore, managing myopia in a holistic manner means not only correcting vision for clear sight but also addressing the abnormal elongation of the eye. By reducing the abnormal eye elongation, the risk of long-term vision-threatening complications could be reduced.
Current understanding of myopia management options for children
Navigating through managing options for myopia in children can be overwhelming, especially considering that many treatments have shown effectiveness and a favorable safety profile in studies but do not have regulatory approval from regulatory bodies for various reasons. This section aims to assist parents in understanding the range of effective treatments and eye habits that have been studied and utilized for children with myopia.
Treatments for vision correction
Glasses or contacts: The standard treatment for myopia is wearing glasses or contacts. It is crucial to follow the prescription and wear the eyewear. Wearing underpowered glasses or not wearing them as instructed may increase the risk of myopia progression. It's important to note that regular glasses alone do not slow down abnormal eye elongation, but they can augment interventions that correct vision, such as atropine treatment and outdoor time.2,3
Refractive or laser surgery: This treatment option is recommended when myopia no longer progresses. It involves using a laser to reshape the cornea, resulting in a decreased need for prescription lenses. However, it's important to understand that surgical treatments are not suitable for everyone. Please discuss this with an eye surgeon for more information. 2,3
Treatments for slowing down abnormal eye elongation
Atropine: Low-concentration atropine eye drops, used once every night, have shown promising results in preventing myopia onset and slowing down the elongation of the eye. Moreover, numerous studies have demonstrated the effectiveness and safety profile of atropine.2,3 Similar to why many doctors may need to prescribe medication off-label, the reason why low-concentration atropine has not received approvals from regulatory bodies, such as FDA or EMA, is likely due to the lack of patent protection, making it unprofitable for companies to invest in the required clinical studies.
Repeated low-level red light therapy (RLRL)*: Although not yet approved or commercially available in North America, this emerging treatment has shown exciting potential for myopia control. Research indicates a shortening of the axial length after 12 months of RLRL treatment, making it the first treatment to demonstrate an effect beyond stopping progression. However, it is essential to point out that further studies are needed to evaluate its long-term efficacy and safety.15
*The device has received CE mark and was reported by a member of Myopia Control and Care support group that a UK clinic carried the device.
Treatments for both vision correction and slowing down abnormal eye elongation
Myopia control glasses: These specially designed glasses not only correct nearsighted vision but also slow down abnormal eye growth. Unlike regular glasses, myopia control glasses have two areas—the correction area in the center, which acts like regular lenses, and the myopia control area, tailored to create the desired effect.2,3
Myopia control soft contact lenses: In the US, the only FDA-approved myopia control treatment is soft contact lenses, MiSight. Similar to myopia control glasses, these special contact lenses have both a correction area and a myopia control area. They are typically available as daily wear lenses.2,3
Orthokeratology (Ortho-K): This procedure involves using specially designed and patient-tailored hard contact lenses that gently reshape the cornea. Children wear these lenses at night, providing temporary correction the next day and slowing down abnormal eye elongation at the same time.2,3
Healthy habits and environment for slowing down abnormal eye elongation
Outdoor time: Encouraging your child to spend at least two hours outdoors each day can have a protective impact against myopia. Research has consistently shown that increased outdoor time is effective in reducing the onset and progression of myopia. The best part is, it's free!16
Taking breaks: If your child spends a significant amount of time engaged in near work, such as reading or studying, regular breaks are important.2,3 While the traditional 20/20/20 rule suggests taking a 20-second break every 20 minutes to look at an object 20 feet away, recent research has questioned its effectiveness in reducing the risk of myopia progression and has recommended taking a 5-minute break every 30 to 60 minutes instead to allow the eyes to rest and minimize the risk associated with prolonged near work.17
Optimizing indoor lighting: Research has demonstrated that increasing the light level to 500 lux in school classrooms has a significant impact on the onset, refraction, and axial elongation of myopia. It may be reasonable to hypothesize the same may be observed in a home setting. Moreover, based evidence available, experts suggest optimizing indoor lighting by using incandescent bulbs instead of fluorescent or LED. 3
Conclusion
In conclusion, understanding myopia is essential for parents of children with this condition. Myopia is influenced by genetics and environmental factors. Managing myopia requires correcting vision and addressing abnormal eye elongation. Treatments like glasses, contact lenses, and atropine eye drops can help, along with healthy habits like spending time outdoors, taking regular breaks from near work, and optimizing indoor lighting.
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10. Rozema J, Dankert S, Iribarren R, Lanca C, Saw SM. Axial Growth and Lens Power Loss at Myopia Onset in Singaporean Children. Invest Ophthalmol Vis Sci. 2019;60(8):3091-3099. [Link]
11. Tideman JW, Snabel MC, Tedja MS, et al. Association of Axial Length With Risk of Uncorrectable Visual Impairment for Europeans With Myopia. JAMA Ophthalmol. 2016;134(12):1355-1363. [Link]
12. Wakabayashi T, Ikuno Y, Oshima Y, Hamasaki T, Nishida K. Aqueous Concentrations of Vascular Endothelial Growth Factor in Eyes with High Myopia with and without Choroidal Neovascularization. J Ophthalmol. 2013;2013:257381. [Link]
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15. Liu G, Li B, Rong H, et al. Axial Length Shortening and Choroid Thickening in Myopic Adults Treated with Repeated Low-Level Red Light. J Clin Med. 2022;11(24):7498. Published 2022 Dec 17. [Link]
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17. Pucker, Andrew D, and Timothy J Gawne. “Fighting Myopia with Intermittent Nearwork Breaks: 20 Seconds Every 20 Minutes Might Not Be Enough Time.” Optometry and vision science : official publication of the American Academy of Optometry vol. 100,1 (2023): 31-32. [Link]
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