Myopia is a common eye condition, classified as a refractive error, in which a person with myopia sees nearby objects clearly but has difficulty seeing objects at a distance clearly. This visual disorder occurs when light focuses in front of the retina rather than directly on its surface, as it does under normal conditions. Understanding the causes and pathophysiological mechanisms of myopia is essential for the prevention, early diagnosis, and proper management of this condition, through both optical correction (glasses, contact lenses) and modern therapeutic options, such as refractive surgery or interventions to slow myopia progression.
Genetic and environmental causes
The role of genetics in the development of myopia
Genetics plays an important role in the predisposition to develop myopia. When one or both parents have myopia, the risk that the child will develop the same eye condition is significantly increased. Molecular genetic studies have identified numerous genetic markers and candidate genes associated with an increased risk of myopia, involved in processes such as axial growth of the eyeball and regulation of retinal visual signals. However, the influence of genetic factors may be summarized as follows:
| Factor | Influence |
|---|---|
| Family history of myopia | Increased likelihood of myopia in the child |
| Genes identified as associated with myopia | May increase the risk of developing myopia |
However, genetics is not the only determining factor. Myopia is considered a condition with a multifactorial etiology, in which the interaction between genetic predisposition and environmental factors influences the onset and progression of the disease. Therefore, even if a genetic predisposition exists, a person will not necessarily develop myopia.
The influence of environmental factors on myopia development
The environment has a significant impact on the development of myopia, especially during childhood, when the eye is undergoing growth and functional shaping. An appropriate balance between exposure to near activities and time spent outdoors is crucial for maintaining visual health. Below is a summary of the impact of these factors on myopia development:
| Environmental factor | Impact on myopia |
|---|---|
| Long periods spent performing activities that require near vision (reading, writing, using screens) | May contribute to the onset and progression of myopia. |
| Lack of exposure to natural light (insufficient time spent outdoors) | May contribute to the onset and progression of myopia. |
Recent studies on the causes of myopia
Recent studies continue to investigate the causes of myopia, highlighting the complex interaction and dynamics between genetic and environmental factors. Research suggests that exposure to natural light stimulates the release of dopamine in the retina, which may inhibit axial growth of the eyeball, thereby reducing the risk of myopia. The influence of different types of screens, as well as viewing distance and duration of exposure on the developing eye, is also being studied in order to provide more precise recommendations regarding their use. It is important for parents to be aware of these modifiable risk factors and apply simple but effective preventive measures, such as:
- encouraging at least 1–2 hours daily outdoors
- limiting time spent in front of screens
- maintaining an appropriate working distance during near activities
- creating an environment with suitable lighting
Risk factors
Types of near activities that affect vision
Near activities, such as reading, writing, or handicrafts, require sustained ocular accommodation because the eyes must focus intensely on objects at a short distance. Prolonged exposure to such activities, without adequate breaks, may induce visual stress and, over time, may contribute to the onset or worsening of myopia, particularly in children and adolescents, whose visual system is still developing. Alternating near activities with periods of visual relaxation involving focusing at a distance (for example, looking out of a window or spending time outdoors) is recommended, to allow the eye muscles to relax and to reduce the risk of axial elongation of the eyeball. Further information about activities and their effects can be found in the table below:
| Activity Type | Possible Effect |
|---|---|
| Near activities (reading, writing, handicrafts) | May contribute to the development and progression of myopia, especially in children and adolescents. |
Screen use and associated risks
Excessive screen use is an important risk factor for the development of myopia, especially in children and adolescents. Studies show that prolonged periods spent in front of screens at a viewing distance that is short may lead the eye to adapt to near vision, thereby favoring the onset and progression of myopia. In addition, the blue light emitted by screens may contribute to asthenopia (eye fatigue) and affect sleep quality by interfering with melatonin secretion; these factors may indirectly influence visual health and worsen symptoms of existing myopia.
Recommendations for reducing the impact of screens
Limiting screen time, taking regular breaks, adjusting screen brightness, and encouraging outdoor activities may reduce the negative impact of screens on visual function.
To reduce this impact, limiting exposure to screens is recommended, especially in children, whose visual system is developing.
During near activities, it is important to take regular eye breaks, for example, every 20 minutes, focusing on an object approximately 6 meters (20 feet) away for 20 seconds (the 20-20-20 rule). This technique helps reduce eye fatigue and prevent dry eye syndrome.
In addition, adjusting screen brightness according to ambient light and using blue-light filters may help reduce visual discomfort and protect the retina from prolonged exposure to potentially harmful radiation.
Furthermore, it is crucial to encourage outdoor activities and daily exposure to natural light, which have a protective effect in preventing the onset and progression of myopia.
If symptoms such as blurred distance vision, frequent blinking, eye pain, or reduced visual performance occur, a specialist eye examination is recommended for evaluation and early intervention.
Myopia and the role of natural light
Benefits of natural-light exposure for the eyes
Exposure to natural light plays a crucial role in the healthy development of visual function, especially in children, reducing the risk of developing myopia.
Natural light stimulates the release of dopamine in the retina, a neurotransmitter that inhibits axial growth of the eyeball, thereby reducing the risk of developing myopia. Studies show that spending sufficient time daily outdoors significantly reduces the risk of developing myopia, even in people with a genetic predisposition.
Therefore, it is essential to encourage outdoor activities as part of the daily routine, not only to stimulate the visual system but also to support overall eye health.
How natural light influences myopia development
Natural light influences myopia development by stimulating dopamine release in the retina, helping maintain normal eye growth.
The mechanism by which natural light acts in preventing myopia is related to retinal dopamine, a neurotransmitter that regulates axial growth of the eyeball. Dopamine inhibits excessive elongation of the eyeball, an anatomical process characteristic of axial myopia.
Lack of exposure to natural light may accelerate axial growth, favoring the onset and progression of myopia. Thus, ensuring adequate time spent outdoors in natural light represents an important preventive strategy.
Tips for increasing exposure to natural light
To increase exposure to natural light, spending at least 1–2 hours a day outdoors, especially during the daytime, is recommended. Outdoor activities such as sports, walks in the park, or games are excellent ways to benefit from the photoprotective effects of natural light on the eyes.
Even on cloudy days, ambient natural-light levels are significantly higher than indoor artificial light, having a positive impact on regulating eye growth.
It is important for this exposure to be an integral part of the daily routine, especially for children, since childhood is a critical period for the normal development of visual function and the prevention of juvenile myopia.
Myopia at different ages
Myopia in children and adolescents
Early diagnosis of myopia in children is crucial because its progression may accelerate during periods of active growth.
Myopia in children and adolescents is an increasingly common vision problem, influenced by genetic and environmental factors, particularly in the context of possible progressive myopia.
Regular eye examinations are essential for detecting myopia and monitoring changes in refractive errors. Optical correction with glasses or contact lenses is important to ensure optimal visual acuity and prevent eye strain.
Myopia in adults
Myopia in adults may be a pre-existing refractive condition that began in childhood, or it may have a late onset during adulthood.
Risk factors include prolonged use of electronic devices, intensive reading at a short distance, and genetic predisposition.
Although myopia progression is usually slower in adults, periodic monitoring of visual acuity and correction with glasses or contact lenses are important to maintain optimal quality of life and prevent symptoms of asthenopia (eye fatigue).
In some cases, adults may choose refractive surgical procedures, such as myopia surgery, to permanently correct myopia when refractive stability exists and there are no ophthalmic contraindications.
Myopia and older adults
In older adults, myopia may coexist with other common eye pathologies, such as cataracts or age-related macular degeneration (AMD).
It is important for older adults with myopia to undergo regular eye check-ups to monitor eye health and detect possible complications.
Personalized optical correction, usually with glasses, is essential, not only for maintaining visual acuity but also for preventing household accidents, such as falls caused by impaired vision.
In some cases, special lenses or surgical procedures may be needed to improve vision.
Practical daily steps
Creating an optimal work or study environment
Creating an optimal work or study environment is essential for protection, especially in the context of possible progressive myopia.
Ensure that you have adequate ambient lighting, avoiding direct light that may cause distracting reflections on the screen and intensify visual discomfort.
Position the screen at least 50–70 cm from the eyes and adjust its height so that the top edge of the screen is at eye level.
Take regular breaks to relax your eyes and avoid visual fatigue.
Use a document holder positioned close to the monitor. It may help maintain correct posture and reduce repetitive movements of the head and eyes.
Visual hygiene rules for children
Limiting screen time, encouraging outdoor activities, and having regular eye examinations are essential for maintaining optimal visual hygiene in children.
To protect children’s eye health, it is important to establish clear visual hygiene rules.
Limit time spent in front of screens and encourage outdoor activities.
Ensure that children have adequate lighting when reading or writing and hold materials at a suitable distance.
Encourage children to take regular visual breaks and look into the distance to relax the eye muscles involved in near focusing.
Regular eye examinations are essential for detecting possible vision problems and correcting them in time.
Diet and supplements for eye health
A balanced diet rich in vitamins and antioxidants is essential for maintaining the health of the visual system and preventing degenerative eye conditions.
Consume foods rich in vitamin A, vitamin C, vitamin E, vitamin D, lutein, and zeaxanthin, such as carrots, spinach, broccoli, citrus fruits, and eggs.
In some cases, especially in people with inadequate dietary intake or chronic conditions, dietary supplements may be recommended to ensure an adequate intake of essential nutrients for eye health.
Consult your ophthalmologist to find out which supplements are suitable for you.
Frequently asked questions about the causes of myopia
How many hours of screen time increase the risk?
More than 2–3 hours a day in front of screens, especially at a short distance, may increase the risk of developing myopia in children. Although there is no precise screen-use limit that triggers the onset of myopia, risk is influenced by factors such as age, genetic predisposition, and viewing distance.
Nevertheless, studies suggest that spending more than 2–3 hours a day in front of screens, especially at a short distance, may increase the risk of developing myopia, particularly in children. It is important to alternate screen time with regular breaks and complement it with outdoor activities to support normal development of the visual system.
What adjustments can I make today?
Start today with simple but effective adjustments that may have a significant impact on your visual health: apply the 20-20-20 rule (a 20-second break every 20 minutes of near activity, looking at a distance of 6 meters), adjust the distance from the screen (50–70 cm), ensure adequate ambient lighting, and spend time outdoors.
These simple adjustments may reduce eye fatigue and contribute to preventing myopia. If you have symptoms of myopia, consult an ophthalmologist for a complete evaluation. Adjusting your lifestyle may positively influence myopia progression.
How can I tell whether my child has myopia?
Warning signs include difficulty seeing clearly objects at a distance, sitting excessively close to the television or blackboard, frequent eye rubbing, or complaints of headaches, especially after activities that require vision. If you notice these symptoms, schedule an eye examination for your child.
Early diagnosis and appropriate intervention may help manage myopia and prevent complications. Do not ignore the symptoms, because myopia in children can progress rapidly, especially without appropriate monitoring and intervention.
How can children and adults prevent myopia from developing over time?
Preventing myopia may include limiting time spent in front of screens, encouraging outdoor activities, and ensuring adequate lighting during near activities. Regular monitoring of vision is also important, especially in children, to detect early any change in visual acuity.
What should people with myopia know about lifestyle adjustments?
People diagnosed with myopia should pay attention to adjusting their visual environment and lifestyle to prevent eye fatigue and worsening of the condition. They should organize their work or study space with adequate lighting, maintain a proper distance from visual objects, including screens, and take regular breaks during activities involving prolonged focusing at short distances.
Regular eye examinations are essential for monitoring myopia progression and adjusting treatment. These measures may help manage symptoms and prevent myopia progression.