Myopia, commonly known as nearsightedness, has emerged as a significant global health concern, affecting a substantial portion of the world’s population. This vision condition, where distant objects appear blurred while close objects remain clear, is rapidly increasing in prevalence across all age groups, particularly among children and adolescents. Projections indicate that by 2050, approximately half of the world’s population, or about 5 billion people, will have some degree of myopia. This rise has led experts to characterize the situation as a “myopia epidemic,” highlighting the urgency of addressing this widespread visual impairment.
What Myopia Is
Myopia is a refractive error where the eye’s shape prevents light from focusing directly on the retina, the light-sensitive tissue at the back of the eye. Instead, light rays converge in front of the retina, causing distant images to appear blurry. This occurs when the eyeball grows too long, or the cornea, the clear front surface of the eye, is too steeply curved. Both factors cause light to bend excessively, leading to a focal point that falls short of the retina.
The eye’s natural lens helps focus light by changing its shape for different viewing distances. In a myopic eye, the elongated shape means light from distant objects cannot be properly focused, resulting in blurry vision. While often diagnosed in school-aged children, myopia can continue to progress through adolescence and into early adulthood as the eye continues to grow.
Factors Driving the Increase
The rise of myopia is attributed to a combination of genetic and environmental factors. While a family history of myopia increases an individual’s likelihood, lifestyle factors are increasingly recognized as significant contributors. This suggests that while some individuals may be genetically more susceptible, modern living habits are exacerbating this genetic tendency.
A primary environmental factor is the increase in “near work” activities, involving prolonged focus on close-up objects. This includes extensive use of digital screens like smartphones, tablets, and computers, as well as prolonged reading. Sustained near focus can lead to eye strain and changes in the eye’s focusing mechanism, potentially contributing to eye elongation. Studies suggest a link between screen time and myopia progression.
Another significant factor is the reduced time children and adolescents spend outdoors. Research shows that increased exposure to natural light and outdoor activities can reduce the risk of myopia onset and slow its progression. It is believed that natural light stimulates the release of dopamine in the retina, which may inhibit eyeball lengthening. Spending at least 90 to 120 minutes outdoors daily, even on cloudy days, is recommended to help support eye health.
The combination of increased near work and decreased outdoor time creates an environment conducive to myopia development. Urbanization and changes in educational systems, often emphasizing indoor academic activities over outdoor play, further contribute to this imbalance. This shift means eyes are frequently engaged in demanding close-up tasks with insufficient exposure to the beneficial effects of natural light and distant viewing.
Health Risks
Beyond blurred distance vision, myopia, particularly high myopia, carries several long-term health risks. High myopia is generally defined as a refractive error of -6.00 diopters or more. The elongation of the eyeball stretches and thins the delicate tissues of the eye, increasing susceptibility to various conditions.
One serious complication is retinal detachment, where the retina separates from its underlying support. Myopic eyes have a stretched, thinner retina, making them prone to tears and detachment. Even mild myopia can triple the risk of retinal detachment, while high myopia can increase this risk by 20 to over 45 times compared to individuals without myopia. This condition requires urgent medical attention to prevent permanent vision loss.
Myopia also increases the risk of glaucoma, which damages the optic nerve, often due to increased fluid pressure within the eyeball. Individuals with moderate to high myopia have a nearly 50% higher risk of developing glaucoma. Glaucoma is often asymptomatic in its early stages, earning it the nickname “silent thief of sight,” as it can lead to gradual and irreversible vision loss if untreated.
Myopic individuals are also at a higher risk for cataracts, a clouding of the eye’s natural lens that impairs vision. While cataracts commonly occur with age, myopia can lead to their earlier onset. Myopic maculopathy, also known as myopic macular degeneration, is another severe complication where the central retina, responsible for sharp, detailed vision, undergoes degenerative changes due to the stretching of the eyeball. This condition can result in significant and often irreversible visual impairment.
Prevention and Control Strategies
Addressing the rise of myopia involves a multi-faceted approach, combining lifestyle adjustments with medical interventions to prevent onset or slow progression. Encouraging children to spend more time outdoors is a widely recommended strategy. Aiming for at least 90 to 120 minutes of outdoor time daily can significantly reduce the risk of myopia development and progression, regardless of the specific activity.
Limiting sustained near work and promoting proper viewing habits are important. This includes taking regular breaks from digital devices and close-up tasks, often advised using the “20-20-20 rule”: every 20 minutes, look at something 20 feet away for 20 seconds. Maintaining appropriate viewing distances and ensuring good lighting during near work can further reduce eye strain.
For managing existing myopia, several medical interventions are available. Low-dose atropine eye drops (0.01% to 0.05%) have shown effectiveness in slowing myopia progression by relaxing the eye’s focusing ability and reducing eye elongation. These drops are usually applied once daily.
Another option is orthokeratology (Ortho-K), which involves wearing rigid gas permeable contact lenses overnight. These lenses gently reshape the cornea, temporarily correcting myopia and allowing for clear daytime vision without glasses or daytime contacts. Ortho-K has been shown to slow axial elongation, a key factor in myopia progression, by reducing peripheral defocus.
Multifocal contact lenses are also used. They are designed with different powers to provide clear vision at all distances while also slowing eye growth. These lenses help to create a peripheral defocus, which is thought to signal the eye to slow its elongation. Regular eye exams are also important for early detection and monitoring of myopia progression, allowing for timely intervention and appropriate control strategies.