Myopia Causes – Genetics, Lifestyle and Other Risk Factors
Myopia, or short-sightedness, occurs when the eye grows too long or the cornea (the clear front surface of the eye) is too curved. This causes light entering the eye to focus in front of the retina rather than directly on it, making distant objects appear blurry.
What Causes Myopia?
Myopia causes can be influenced by genetics, environmental factors, and individual characteristics. Reasons for myopia vary, but research suggests that the condition typically develops due to a combination of:
- Genetics – Myopia often runs in families. A child with one short-sighted parent has three times the risk of developing myopia, and this risk increases to six times if both parents are short-sighted.
- Environmental Factors – Modern lifestyles, particularly in children, play a significant role in the rising rates of myopia. A lack of outdoor time, prolonged near work such as reading, studying, or excessive screen use, and reduced exposure to natural light have all been linked to an increased risk of developing myopia. Extended years of education is also a risk factor for myopia.
Childhood vs. Adult-Onset Myopia
Childhood onset myopia is most commonly caused by the eyes growing too quickly.
Lifestyle and Myopia Progression
A lack of outdoor time is one of the most significant causes of myopia in children. Studies show that daily exposure to natural light plays a crucial role in healthy eye development. However, as screen time increases and outdoor activity decreases, more children are developing short-sightedness at a younger age.
A recent report, The Australia and New Zealand Child Myopia Report – A Focus on Future Management revealed that:
- Only 12% of parents were aware of the lifestyle factors that contribute to myopia, such as low levels of outdoor activity, prolonged near tasks like reading and gaming, and insufficient exposure to natural light.
- One-third of Australian children had never had an eye examination, despite vision problems being linked to poor school performance.
Why Early Myopia Matters
Rates of high myopia are increasing, and the earlier a child develops myopia, the worse it is likely to become. Earlier onset allows myopia to progress for a longer period, leading to stronger prescriptions and higher risks of eye health complications such as:
- Retinal detachment
- Glaucoma
- Cataracts
- Myopic maculopathy
Since myopia is now considered a growing public health issue, regular eye examinations are essential, especially for children.
Adult onset myopia often develops due to prolonged close-up work, such as when undertaking university studies, or as a response to fatigued eye focusing muscles. Some adults may also experience myopia due to visual stress or health conditions such as diabetes.
- Some people may experience blurred distance vision only at night. With "night myopia," low light makes it difficult for the eyes to focus properly. Or the increased pupil size during dark conditions allows more peripheral, unfocused light rays to enter the eye.
- People who do an excessive amount of near-vision work may experience a false or "pseudo" myopia. Their blurred distance vision is caused by overuse of the eyes' focusing mechanism. After long periods of near work, their eyes are unable to refocus to see clearly in the distance. Clear distance vision usually returns after resting the eyes. However, constant visual stress may lead to a permanent reduction in distance vision over time.
FAQs About Myopia Causes
Can diabetes cause myopia?
Yes, diabetes can contribute to the development of myopia. High blood sugar levels can cause fluctuations in the shape of the lens, leading to temporary or permanent changes in vision.
Can screen time cause myopia?
Excessive screen time is considered a risk factor for myopia development in children. Prolonged near work, including screens and reading, may lead to increased eye strain, dry eye and the progression of short-sightedness.
Does reading in the dark cause myopia?
Reading in dim lighting does not directly cause myopia, but it can contribute to eye strain, making it harder for the eyes to focus. Over time, excessive strain may lead to visual discomfort and progression of myopia in those already prone to it.
Do phones cause myopia?
Frequent phone use at close distances may increase the risk of developing myopia, especially in children. Research suggests that prolonged near work without breaks can contribute to eye strain and changes in eye growth patterns.
What causes myopia to get worse?
Myopia progression is often linked to extended periods of near work, lack of outdoor time, and genetics. Without intervention, short-sightedness can worsen, increasing the risk of serious eye conditions in adulthood.
Are you born with myopia?
Most people are not born with myopia, but genetics play a significant role. If one or both parents have myopia, their child is at a higher risk of developing it, especially if combined with modern lifestyle factors such as high screen time and low outdoor activity.
Disclaimer: No information provided on the Good vision for life website is intended to constitute or substitute advice from visiting an optometrist. You should seek appropriate personalised advice from a qualified optometrist about any eye health and vision conditions.
