This comprehensive review reveals that myopia (nearsightedness) has reached epidemic levels globally, with half the world population projected to be affected by 2050. While genetic factors play a role, environmental factors like limited outdoor time and extensive near work significantly contribute to myopia development. Among all interventions, low-dose atropine eye drops (0.01%) demonstrate the most effective long-term results for slowing myopia progression with minimal side effects, while increased outdoor time shows the strongest protective effect against myopia onset in children.

Preventing Myopia Progression: A Comprehensive Guide for Patients and Families

Table of Contents

• Introduction: The Global Myopia Epidemic
• How This Research Was Conducted
• What Causes Myopia: Genetics and Environment
• Environmental Factors: Outdoor Time and Near Work
• Treatment Options for Slowing Myopia Progression
• Key Conclusions and Recommendations
• Study Limitations
• Source Information

Introduction: The Global Myopia Epidemic

Myopia, commonly known as nearsightedness, has become one of the most widespread vision problems worldwide. This condition occurs when the eye grows too long from front to back (axial elongation), causing light to focus in front of the retina instead of directly on it. The result is clear vision for nearby objects but blurred vision for distant objects.

The prevalence of myopia has dramatically increased in recent decades, particularly in developed countries. In East and South-East Asia, the situation has reached epidemic proportions, with 80-90% of children aged 17-18 affected. Western countries are also experiencing significant increases, with studies showing 46% of 25-year-olds affected compared to only 15% of 75-year-olds.

Alarming projections estimate that by 2050, approximately 4.758 billion people (49% of the world population) will have myopia, and 938 million (9.8%) will have high myopia (defined as -6.00 diopters or worse). This represents a massive public health concern because high myopia significantly increases the risk of serious eye complications including retinal detachment, glaucoma, cataracts, and myopic maculopathy, which can lead to permanent vision loss.

The earlier myopia develops in childhood, the more severe it tends to become in adulthood. This systematic review examines all available strategies—behavioral, interventional, and pharmacological—that can help slow myopia progression in children, evaluating not just effectiveness but also side effects, patient tolerability, and long-term benefits.

How This Research Was Conducted

Researchers conducted a comprehensive systematic review of all available scientific literature up to December 2017. They searched multiple medical databases including PubMed, MEDLINE, and the Cochrane Collaboration using specific search terms related to myopia control and prevention.

The search included terms such as "myopia" combined with "control," "progression," "pediatrics," "prevention," "atropine," "orthokeratology," "contact lenses," "spectacles," "outdoor activities," "near work," and several other relevant terms. The researchers thoroughly assessed all pertinent articles and examined their reference lists to identify additional studies that might have been missed in the initial search.

All English-language articles dealing with myopia control therapies were considered. The reviewers evaluated study eligibility first based on titles and abstracts, then obtained full manuscripts for all potentially relevant studies before making final inclusion decisions. This rigorous approach ensured that the review incorporated the highest quality evidence available on myopia prevention strategies.

What Causes Myopia: Genetics and Environment

Myopia develops through a complex interaction between genetic factors and environmental influences. Understanding both components is essential for effective prevention strategies.

Genetic Factors

Research has consistently shown that children with myopic parents have a significantly higher risk of developing myopia themselves. Studies of Australian children demonstrated that parental myopia and ethnicity significantly influence both spherical equivalent refraction and axial length measurements.

While common myopia is generally transmitted as a complex trait, high myopia can follow different inheritance patterns including autosomal dominant, autosomal recessive, and X-linked recessive inheritance. Twin studies have been particularly revealing—research on identical twins shows that myopia has a heritability of 90%, meaning genetics accounts for the vast majority of the variation in myopia risk between these genetically identical individuals.

Researchers have identified 18 specific genetic locations (called loci) associated with myopia and high myopia, including MYP2, MYP3, and MYP5. These discoveries have helped identify candidate genes that may be responsible for the disease. One important pathway involves TGF-beta/BMP signaling, which regulates collagen production in the sclera (the white outer layer of the eye). Reduced expression of TGF-beta isoforms in the sclera is associated with decreased collagen synthesis and increased predisposition to pathological axial elongation.

However, genome-wide association studies have found that these known genetic risk factors account for only 0.5-2.9% of the risk for developing myopia. This suggests that non-genetic factors—including epigenetic changes and environmental influences—play a much stronger role than previously appreciated.

Biological Mechanisms

The retina appears to play a crucial role in controlling eye growth in response to visual signals. Animal studies have shown that manipulating peripheral retinal defocus with special lenses can modify eye growth and refractive status. Specifically, imposing peripheral hyperopic defocus (where peripheral light focuses behind the retina) can produce axial myopia.

Several biochemical pathways have been investigated in myopia development. The dopamine system has emerged as particularly important. Multiple studies have shown that reduced dopamine levels are associated with myopic eye growth in animal models. Chickens treated with negative lenses showed decreased levels of DOPAC (a dopamine metabolite) in the vitreous humor.

Dopamine exerts its effects through specific receptors (D1-like and D2-like receptors) located on various retinal cells. Recent findings suggest that both receptor types work together in myopia development rather than just D2 receptors as previously thought. The retinal pigment epithelium (RPE) also plays a crucial role by releasing growth factors that regulate scleral remodeling in response to visual signals.

Other molecules being investigated include 7-methylxanthine, which has been shown to reinforce the posterior sclera in young rabbits by increasing collagen content, and melatonin, which appears to influence choroidal thickness and may be involved in light exposure effects on myopia development.

Environmental Factors: Outdoor Time and Near Work

Environmental factors, particularly time spent outdoors and engaging in near work activities, significantly influence myopia development and progression.

Outdoor Activities

Multiple epidemiological studies have demonstrated the protective effect of outdoor activities against myopia development. The Guangzhou randomized trial followed 1,903 children aged 6-7 over three years, comparing those who received additional daily outdoor activity with controls who maintained usual patterns.

The intervention group showed significantly less myopic progression (-1.42 diopters vs. -1.59 diopters in controls, a difference of 0.17 diopters) and a 23% reduction in myopia incidence. Similar results came from a Taiwanese study where a recess outside the classroom program reduced myopia incidence from 17.65% to 8.41% after one year.

The protective effect appears strongest for preventing myopia onset rather than slowing progression in already myopic children. A meta-analysis confirmed that more time outdoors reduces both incidence (risk ratio = 0.536 in clinical trials) and prevalence (odds ratio = 0.964 in cross-sectional studies) of myopia, but found no significant association with progression rate.

Residential area also influences risk, with urban and suburban children showing higher myopia prevalence (10.1% and 12.3% respectively) compared to exurban (3.8%) and rural (1%) areas in an Indonesian study. This likely reflects both reduced outdoor time and increased near work associated with higher education demands in urban settings.

The biological mechanism likely involves dopamine release stimulated by bright light exposure. Animal studies show that high luminance levels can retard myopia development, and this effect is blocked by dopamine antagonists.

Near Work Activity

The evidence regarding near work (reading, writing, screen time) as a risk factor for myopia is more mixed. A Singapore study found teenagers spending more than 20.5 hours weekly on reading and writing were significantly more likely to develop myopia (odds ratio 1.12).

The Sydney Myopia Study found that reading distance closer than 30 cm and continuous reading longer than 30 minutes increased myopia risk by 2.5 times and 1.5 times respectively in 12-year-old Australian children. However, total near work time wasn't significant in multivariate analyses.

A recent systematic review and meta-analysis of 27 studies found that more near work was associated with higher odds of myopia (odds ratio = 1.14), with each additional diopter-hour of weekly near work increasing odds by 2%.

Higher education levels consistently correlate with higher myopia prevalence, likely reflecting both increased near work and reduced outdoor time. This evidence confirms the multifactorial nature of myopia, where near work constitutes an important independent risk factor among many contributing elements.

Treatment Options for Slowing Myopia Progression

Several interventions have been studied for slowing myopia progression, with varying degrees of effectiveness, side effects, and practical considerations.

Biofeedback Visual Training

Based on theories from the 1920s suggesting that extra-ocular muscle overwork causes accommodation changes, various biofeedback techniques have been attempted. However, clinical evidence does not support their effectiveness.

A prospective study of 33 female students found no significant differences after 12 months of acoustic biofeedback training. Previous non-randomized studies similarly reported no efficacy, and a case-control study of Chinese eye exercises found no significant association with myopia risk or progression over two years. Currently, no consistent evidence supports biofeedback visual training for myopia control.

Spectacles and Contact Lenses

While single-vision spectacles and contact lenses correct vision, they don't significantly slow progression. Progressive addition lenses (PALs) and bifocal spectacles have been tested based on theories that they reduce retinal hyperopic blur by decreasing accommodative lag during near work.

The Correction of Myopia Evaluation Trial (COMET) studied 469 children aged 9 over three years. Those receiving PALs with +2.00 addition showed a statistically significant but clinically small gain of only 0.2 diopters compared to standard single-vision lenses. Subgroup analyses suggested greater benefit for children with larger accommodative lags (>0.43D) combined with near esophoria.

The COMET2 study specifically selected myopic children with near esophoria and significant accommodative lag, finding only a 0.28 diopter benefit after three years. A 3-year Finnish randomized controlled trial of 240 schoolchildren found bifocal or reading spectacles ineffective despite theoretical benefits.

Soft contact lenses specifically designed for myopia control have shown modest benefits. One study of 186 American children aged 8-18 found treated participants progressed -0.22±0.34 diopters compared to -0.79±0.43 diopters in controls after one year. A larger Hong Kong study of 221 children aged 8-13 found treated groups progressed 0.30 diopters/year compared to 0.40 diopters/year in controls over two years.

Orthokeratology (Ortho-K)

Orthokeratology involves wearing rigid gas-permeable contact lenses overnight to temporarily reshape the cornea, providing clear vision during the day without glasses or contacts. A pilot study of 35 Hong Kong children aged 7-12 found a gain of 2.09±1.34 diopters for treated participants after two years.

A randomized single-masked study of 102 Hong Kong children aged 6-10 found axial elongation of 0.36±0.24 mm in treated groups compared to 0.63±0.26 mm in controls after two years. While showing efficacy, Ortho-K carries risks including infectious keratitis and requires excellent compliance, making it less suitable as first-line therapy for many children.

Pharmacological Treatments

Medication-based approaches have shown the most consistent results for myopia control.

Pirenzepine 2% ophthalmic gel was studied in 353 Singaporean children aged 6-12. After one year, the placebo group progressed -0.84 diopters, while pirenzepine/placebo and pirenzepine/pirenzepine groups progressed -0.70 and -0.47 diopters respectively. An American study of 174 children aged 8-12 found a 0.41 diopter gain after two years with pirenzepine treatment.

Atropine has emerged as the most effective treatment. The ATOM1 study of 400 Asian children aged 6-12 found that after two years, the control group progressed -1.20±0.69 diopters with 0.38±0.38 mm axial elongation, while the atropine 1% group progressed only -0.28±0.92 diopters with -0.02±0.35 mm elongation.

Critically, low-dose atropine (0.01%) has proven particularly effective long-term with the lowest rebound effect and negligible side effects compared to higher concentrations. This makes it the current treatment of choice for many clinicians, balancing efficacy with tolerability.

Key Conclusions and Recommendations

Based on the comprehensive evidence review, several clear conclusions and recommendations emerge for patients and families concerned about myopia progression.

First-line prevention: Increased outdoor time provides the strongest protection against myopia onset. Children should spend significant time outdoors daily, with studies suggesting this may reduce incidence by approximately 23%. This approach has no side effects and additional health benefits.

First-line treatment: For children already diagnosed with myopia, low-dose atropine (0.01%) eye drops currently represent the most effective treatment for slowing progression. This concentration provides substantial benefit with minimal side effects and the lowest rebound effect upon discontinuation.

Secondary options: Orthokeratology and specialized contact lenses show moderate efficacy but require careful consideration of risks (particularly infection with Ortho-K) and compliance challenges. These may be appropriate for specific cases where atropine isn't suitable or effective.

Limited benefit: Standard glasses and contact lenses correct vision but don't significantly slow progression. Progressive addition lenses and bifocals provide only minimal benefit for most children, though may help specific subgroups with particular vision characteristics.

Not recommended: Biofeedback visual training and eye exercises show no consistent evidence of effectiveness and shouldn't be relied upon for myopia control.

Families should discuss these options with their eye care professional to develop an individualized plan based on the child's age, myopia severity, progression rate, and specific circumstances.

Study Limitations

While this systematic review provides comprehensive analysis, several limitations should be considered when interpreting the findings.

Most studies focused on specific ethnic populations, particularly Asian children who have higher myopia prevalence. Results may not fully generalize to other ethnic groups with different genetic backgrounds and environmental exposures.

Many studies had relatively short follow-up periods (1-3 years), limiting understanding of truly long-term outcomes and potential rebound effects after treatment discontinuation. Longer-term data is especially needed for newer interventions like low-dose atropine.

The mechanisms behind many interventions aren't fully understood. While we know certain treatments work, exactly how they slow eye growth requires further research to optimize approaches and develop new therapies.

Compliance challenges in real-world settings may differ from controlled trial conditions. Treatments requiring strict adherence (like nightly Ortho-K wear or daily eye drops) may show reduced effectiveness outside research settings.

Finally, most studies measured anatomical outcomes (axial length) and refractive error, but fewer assessed quality of life impacts or functional visual outcomes that matter most to patients.

Source Information

Original Article Title: Prevention of Progression in Myopia: A Systematic Review

Authors: Aldo Vagge, Lorenzo Ferro Desideri, Paolo Nucci, Massimiliano Serafino, Giuseppe Giannaccare, Carlo E. Traverso

Publication: Diseases 2018, 6(4), 92

Note: This patient-friendly article is based on peer-reviewed research originally published in a scientific journal. It preserves all key findings, data, and conclusions while making the information accessible to non-specialist readers.