Eyes on the Future: Causes, Risk Factors, and Implications of Myopia
- Aldrin V. Gomes
- Sep 3
- 7 min read
Updated: Sep 8
Could children be reading or studying too much? Increasing evidence shows that excessive time spent doing “near work,” like reading, studying, or screen time from a short distance, can play a role in developing myopia in children. Myopia (nearsightedness) is a common eye disorder caused by an elongated eyeball, which causes the image of distant objects to fall in front of the eye’s photoreceptors (Morgan et. al, 2012). This causes distant objects to appear blurred and unfocused.
Diopters (D) are a unit of measurement that tell how strong prescription lenses need to be to correct vision. Myopia is defined by an error of -0.5 D and higher (Baird et. al, 2020). Low myopia is between -0.5 to -2.9 D, moderate myopia is between -3.0 to -5.9 D, and severe (high) myopia is defined as -6.0 D or more (Cline, 1997). High myopia is especially concerning as it can cause pathologic myopia, which involves degeneration of parts of the eye and increases the risk of permanent vision changes, like blindness (Baird et. al, 2020).
Myopia often develops in adolescents, teenagers, and young adults, and usually stabilizes in the mid-20s (Morgan et. al, 2012, Baird et. al, 2020). Studies show that the longer an individual has myopia, the more it will have progressed by the time it stabilizes (Baird et. al, 2020). The onset of myopia in children under the age of 11 is increasing, and due to this earlier onset, more and more young adults are showing incidence of severe myopia (Baird et. al, 2020).
How Common is Myopia?
Myopia is one of the most common eye disorders around the world. As of 2020, it was estimated that over 28% of the world’s population has myopia, which translates to almost 2 billion people (Baird et. al, 2020). This prevalence can vary by region. In parts of East Asia, over 80% of school-aged children and young adults have myopia, and between 10-20% of myopia cases are of severe myopia (Baird et. al, 2020). While the prevalence in adults shows less geographic disparity, myopia remains slightly more prevalent in East Asia, Western Europe, and the United States (Matsumura et. al, 2020).
Treatment for Myopia
Eyeglasses or contact lenses are the standard treatment for myopia. Since these methods do not address the root cause of the eyeball elongation or myopia progression, routine eye exams are needed to keep the lens prescription up-to-date with vision changes (Baird et. al, 2020). Treatments to control the elongation of the eyeball, such as orthokeratology lenses–which are lenses that reshape the eyeball while the wearer sleeps–are in use, but the long-term effectiveness of these treatments is still unknown (Baird et. al, 2020). Atropine eye drops are also available for myopia treatment and have shown to slow myopia progression with results that last even after the medication is stopped (Baird et. al, 2020). Surgical options, such as laser-assisted in situ keratomileusis (LASIK) surgery, are also available for adults whose myopia has stabilized (Baird et. al, 2020).
Genetic and Environmental Factors
Myopia is multigenic, meaning that many genes across different parts of the genome can play a role in its onset and progression (Baird et. al, 2020). While genetic predisposition is considerable, the increasing prevalence of myopia is more strongly linked to modern lifestyles and environmental factors.
“Near work,” or activities like reading, studying, and screen use, is strongly associated with myopia onset and progression (Theophanous et. al, 2018). A Singapore study found that children who read more than two books per week had a higher risk of developing myopia (Morgan et. al, 2012). Additionally, digital device use has also been implicated for increased myopia incidence in both children and adults. Since smartphones entered the market in 1997, myopia incidence has increased by 35% (Zorena et. al, 2018).
Outdoor time has also been associated with myopia. Exposure to natural light causes the release of dopamine in the retina, which slows eye elongation (Baird et. al, 2020). Greater time outdoors has shown to prevent myopia onset and slow its progression (Baird et. al, 2020). Children who spend an increased amount of time studying and reading often spend less time outdoors, and this combination of factors, especially if combined with genetic predisposition, can significantly increase the risk of early onset and fast progression of myopia.
Asian Descent
Myopia has earlier onset and faster progression in children of Asian descent compared with other races (Jones-Jordan et. al, 2021). While genetic predisposition may be a contributor, it is hypothesized that this is a result of social factors. The rise of myopia in East and Southeast Asia has been attributed to the rise in mass intensive schooling and increasing educational pressures (Baird et. al, 2020, Morgan et. al, 2012). This contributes to children and adolescents spending more time doing near work, particularly studying, and spending less time outdoors.
Gender Differences
Myopia onset and progression is slightly earlier and faster in female children compared to male children. One study done in 2008 showed that time spent outdoors for school-aged girls was on average 19 minutes less than school-aged boys (Rose et. al, 2008). While a small difference, this suggests that some factors, such as socioeconomic and cultural settings, may limit outdoor activity time for girls and result in increased myopia incidence.
Another study, conducted in 2015, links myopia to changes in estrogen levels during the menstrual cycle and the onset of puberty. This study shows that estrogen levels can cause changes in the thickness of the cornea, which is linked to myopia (Gong et. al, 2015). Since the onset of puberty is typically earlier for girls, this may partially explain earlier myopia onset (Gong et. al, 2015).
Educational Level
Educational level has a strong association with myopia, especially as more time spent attaining education means more near work and less time outdoors (Baird et. al, 2020). Education attainment has also been associated with the differences in myopia levels seen in urban versus rural populations. Compared to rural areas, urban populations have a higher incidence of myopia (Baird et. al, 2020). This is thought to occur because urban areas have higher economic development and higher educational standards (Baird et. al, 2020). There is also a general trend of those from higher socioeconomic status to have higher levels of myopia, which can also be attributed to the correlation between socioeconomic status and educational attainment (Baird et. al, 2020).
Why Should We Be Concerned?
By 2050, it is estimated that nearly 5 billion people will have myopia, which will be roughly half of the world’s population, and approximately 1 in 10 people will have severe myopia (Baird et. al, 2020). Increasing rates of severe myopia are extremely concerning, as this can lead to comorbidities like retinal detachment, glaucoma, and other eye conditions that can cause irreversible blindness (Repka, 2015).
Beyond health risks, patients with myopia report a decreased quality of life, and difficulty in carrying out visual tasks can lead to anger, frustration, and depressive symptoms (Baird et. al, 2020). Myopia also has financial and economic consequences, as patients take on considerable financial responsibility to complete eye exams or get glasses or contact lenses (Repka, 2015). This, along with other side effects like dry eyes from contact lens use and inconvenience from glasses use, can pose significant issues for the global population (Baird et. al, 2020). Furthermore, myopia places a significant cost on public health systems worldwide, as money is needed for surveillance, treatments, and further research (Repka, 2015).
What Can Be Done?
Prevention does not mean discouraging academic activity. Strategies like recess spent outdoors, additional time spent playing outside, and participating in sports and exercise activities outdoors have shown to prevent and decrease progression in children even when engaging in near work (Baird et. al, 2020). Studies suggest that even just a 40 minute increase in outdoor time can decrease the progression of myopia significantly (Repka, 2015). Frequent breaks from near work can also help prevent eye strain and decrease discomfort from symptoms of myopia (Zorena et. al, 2018). Overall, the aim is to balance near work with protective behavior.
So, should you take away your child’s books? Absolutely not. While reading and study are essential, ensuring that children spend time outdoors is just as critical for their long-term health. An afternoon at the park or walking the dog after school could mean a clearer vision for your child tomorrow.
Written by Doaa Shahid and edited by Aldrin V. Gomes, PhD.
References
Baird, P.N., Saw, SM., Lanca, C. et al. Myopia. Nat Rev Dis Primers 6, 99 (2020).
Cline D, Hofstetter HW, Griffin JR (1997). Dictionary of Visual Science (4th ed.). Boston:
Butterworth-Heinemann. ISBN 978-0-7506-9895-5.
Gong JF, Xie HL, Mao XJ, Zhu XB, Xie ZK, Yang HH, Gao Y, Jin XF, Pan Y, Zhou F. Relevant
factors of estrogen changes of myopia in adolescent females. Chin Med J (Engl). 2015
Mar 5;128(5):659-63. doi: 10.4103/0366-6999.151669.
Jones-Jordan, Lisa A., et al. "Myopia progression as a function of sex, age, and ethnicity."
Investigative ophthalmology & visual science 62.10 (2021): 36-36.
Kathryn A. Rose, Ian G. Morgan, Jenny Ip, Annette Kifley, Son Huynh, Wayne Smith, Paul
Ophthalmology, Volume 115, Issue 8, 2008, Pages 1279-1285, ISSN 0161-6420, https://doi.org/10.1016/j.ophtha.2007.12.019.
Myopia. Morgan, Ian G et al. The Lancet, Volume 379, Issue 9827, 1739 - 1748.
Repka MX. Prevention of Myopia in Children. JAMA. 2015;314(11):1137–1139.
doi:10.1001/jama.2015.10723.
Matsumura, Saiko, Ching-Yu, Cheng, Saw, Seing-May. 2020 27 M. Ang, T. Y. Wong (eds.),
Updates on Myopia, https://doi.org/10.1007/978-981-13-8491-2_2.
Theophanous C, Modjtahedi BS, Batech M, Marlin DS, Luong TQ, Fong DS. Myopia
prevalence and risk factors in children. Clin Ophthalmol. 2018 Aug 29;12:1581-1587.
doi: 10.2147/OPTH.S164641.
Zorena, Katarzyna, Aleksandra Gładysiak, and Daniel Ślęzak. "Early intervention and
nonpharmacological therapy of myopia in young adults." Journal of ophthalmology
2018.1 (2018): 4680603.
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