Myopia, also known as nearsightedness, is the most prevalent ocular disorder globally. The rapid increase in its prevalence has raised significant public health concerns. Predictions indicate that approximately half of the world’s population will be myopic by 2050, with 10% experiencing high myopia, which significantly increases the risk of sight-threatening complications. This comprehensive analysis explores the current trends in myopia prevalence, evaluates the efficacy of various pharmacological interventions, and discusses future prospects for myopia control.
Current Trends in Myopia Prevalence
The prevalence of myopia has escalated dramatically worldwide, particularly in urbanized regions of East Asia. For instance, in South Korea, the prevalence of myopia among 19-year-old males surged from 18.3% in 1955 to 96.5% by 2011. Similar trends are observed in Taiwan and China, where the prevalence among young adults ranges from 84% to 97%. In the United States, myopia affects 36.1% of children aged 5 to 17 in urban areas, with a national prevalence of 41.6% among adults aged 12 to 54.
Projections suggest that by 2050, nearly 50% of the global population will be myopic, equating to almost 5 billion people. High myopia is expected to affect around 1 billion individuals, posing a substantial risk for permanent vision impairment. The economic burden is also significant, with potential productivity losses due to uncorrected myopia estimated at $244 billion globally in 2015.
Causes of the Myopia Epidemic
Several factors contribute to the increasing prevalence of myopia:
- Increased Near Work and Screen Time: The rise in digital device usage and prolonged near work activities such as reading and studying are strongly associated with myopia development.
- Reduced Outdoor Time: Limited exposure to natural light and decreased time spent outdoors have been linked to higher myopia risk.
- Urbanization and Education: Higher prevalence is noted in urban environments and among individuals with higher educational attainment, likely due to increased near work and reduced outdoor activities
- Genetic Factors: While environmental factors play a significant role, genetic predisposition also contributes to the risk of developing myopia.
Understanding Atropine Therapy for Myopia
What is Myopia?
Myopia, also known as nearsightedness, is a common vision problem where distant objects appear blurry while close objects can be seen clearly. It often starts in childhood and can progress over time.
Atropine Eye Drops: A New Approach
Atropine eye drops, especially in low concentrations like 0.01%, are being used to slow down the progression of myopia in children. These drops are applied once daily and have been studied in various clinical settings.
Key Findings from Studies
- Study on 6-12 Year Olds
- In a study involving children aged 6-12 with mild to moderate myopia, it was found that using 0.01% atropine eye drops did not significantly reduce the progression of myopia over one year when compared to a control group who did not use the drops.
- However, children using the drops had a noticeable slowdown in myopia progression compared to their progression rate before starting the drops.
- Spanish Studies
- A 5-year study in Spain showed that children aged 9-12 using 0.01% atropine had a much slower progression of myopia compared to those who did not use the drops.
- Another study reported similar findings, with children on atropine showing less increase in eye length and myopia progression over two years.
- Irish Study
- In Ireland, a study with children aged 6-16 showed mixed results. While there was some reduction in myopia progression at 18 months, the difference was not significant after two years.
- Studies in the USA and Australia
- Studies in the USA and Australia with children of various ethnicities did not find significant long-term benefits of 0.01% atropine in slowing myopia progression over two years.
Side Effects
The most common side effect of 0.01% atropine eye drops is blurred near vision. Other side effects are generally mild and include eye irritation and light sensitivity. These side effects are less common with the 0.01% concentration compared to higher concentrations.
Strengths and Limitations of Studies
- Strengths:
- Some studies focused on diverse populations, providing insights into how different groups respond to the treatment.
- The low concentration of atropine (0.01%) minimizes side effects and improves compliance.
- Limitations:
- Many studies did not track myopia progression before starting the drops.
- Parent choice in starting treatment could bias results, as those with children with faster progressing myopia were more likely to start atropine therapy.
- A follow-up period of one year may be too short to observe significant long-term effects.
The effectiveness of 0.01% atropine eye drops in slowing myopia progression remains debated. While some studies show promising results, others do not find significant benefits. Future research should focus on long-term effects, potential genetic factors, and the use of higher doses of atropine.
What to Remember
- Atropine Eye Drops: Used to slow myopia progression in children.
- Effectiveness: Mixed results; some studies show benefits while others do not.
- Side Effects: Generally mild with low concentration (0.01%).
- Future Research: Needed to fully understand long-term benefits and potential genetic influences.
Pharmacological Interventions
Among the measures employed to slow myopia progression, atropine eye drops have emerged as the only pharmacological intervention implemented in clinical practice. Atropine has been reported to have a dose-dependent effect on myopia progression at the cost of increasing the risk of adverse events and rebound effects at higher concentrations.
High-Concentration Atropine
Studies confirm the efficacy of higher concentrations of atropine eye drops (0.5%-1.0%) for myopia control, but side effects and rebound after drop cessation frequently occur. For example, children treated with 0.5% atropine experienced significant reduction in myopia progression, but upon cessation, a rebound effect was observed, with rapid progression of myopia.
Low-Concentration Atropine
Recent research has focused on the efficacy of low-concentration atropine eye drops (0.01%-0.05%). These studies have confirmed that lower concentrations can effectively slow myopia progression with fewer side effects and better compliance. A study involving children aged 6 to 12 years demonstrated that 0.01% atropine eye drops reduced myopia progression significantly compared to a control group, with minimal side effects reported.
Comparative Studies
Numerous studies have confirmed the efficacy of 0.01% atropine eye drops. A five-year study in Spain involving children aged 9 to 12 with myopia ranging from -0.5 to -2.0 D reported a mean annual myopia progression of -0.14 D in the 0.01% atropine group compared to -0.65 D in the control group. Another Spanish study demonstrated reduced myopia progression in the 0.01% atropine group compared to the control group over a two-year follow-up, with significant differences in axial length (AL) elongation as well.
In contrast, a study conducted in Ireland enrolled children aged 6 to 16 years with spherical equivalent (SE) ≤ -0.50 D and found no significant difference in SE changes between the 0.01% atropine group and the placebo group at the two-year visit. However, reduced AL elongation was observed in the atropine group at both the 18-month and 24-month visits compared to the placebo group.
Adverse Reactions and Safety
While 0.01% atropine is generally well-tolerated, side effects such as blurred near vision have been reported. In the study of myopic German schoolchildren treated with 0.01% and 0.05% atropine, children treated with 0.05% atropine exhibited significantly higher anisocoria and a greater loss of accommodation amplitude compared to those treated with 0.01%. These side effects were more pronounced in Caucasian children compared to Asian children.
Innovations in Light-Based Interventions
Recent advancements in light-based therapies offer promising alternatives for myopia control. Repeated low-level red-light therapy has shown potential in reducing myopia prevalence. A year-long study in Shanghai demonstrated that children receiving red-light therapy were half as likely to develop myopia compared to those who did not receive the therapy. However, concerns about safety and the need for further research persist.
The global myopia epidemic necessitates a multifaceted approach, combining lifestyle modifications, pharmacological treatments, and innovative therapies. Continued research and public health initiatives are crucial to mitigate the impact of myopia and prevent future vision impairment. The integration of evidence-based interventions and increased awareness can significantly reduce the burden of myopia worldwide.
reference link :https://www.mdpi.com/1648-9144/60/7/1022
