Myopia is the most common refractive error in Hong Kong. Myopia results when the length of an eyeball is too long. Light rays from the distant object entering the eye are focused in front of the retina instead of on it, resulting in blurred images. The deeper the myopia, the blurrier the distant objects become. Myopia with a degree of -5 diopters or above is classified as high or deep myopia, and it is estimated that by 2050, there will be nearly 5 billion people with myopia globally, with 1 billion at risk of blindness due to deep myopia.
Deep Myopia Can Lead to Blindness!
Myopia is the most prevalent eye condition globally. The growing population with deep myopia increases the incidence of severe myopia-related diseases, such as glaucoma, cataracts, macular degeneration, and retinal detachment. Factors like genetics, excessive screen time and insufficient outdoor activities can exacerbate myopia progression.
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Causes of Deep Myopia
Genetic factors:
Children are more likely to develop high myopia if one or both parents are highly myopic.
Environmental factors:
Prolonged near-work activities like excessive reading, computer/ digital screen use, and lack of outdoor time can increase the risk of developing high myopia.
The Risks of Deep Myopia
Cataracts
Deep myopia can cause the lens to become cloudy, leading to blurred vision and the early onset of cataracts.
Glaucoma
Deep myopia can increase the risk of developing glaucoma, causing peripheral vision loss that gradually narrows the field of vision, ultimately resulting in blindness.
Macular Degeneration
Deep myopia can lead to macular cell degeneration, causing abnormal blood vessels' growth, which can result in blurred, distorted, and deformed vision.
Retinal Detachment
Deep myopia causes the eyeball to elongate and the retina to thin, making it more susceptible to detachment.
Harmful Habits That Worsen Myopia
To prevent myopia from worsening, it is important to avoid the following harmful habits, which can lead to the progression of myopia.
Using phones or reading without adequate lighting
Prolonged exposure to electronic screens
Lack of sufficient rest
Insufficient outdoor activities
Common Misconceptions About Myopia
Can laser eye surgery treat myopia?
It can only change the refractive error, but it cannot change the eyeball elongation. Even if the refractive error is reduced to zero, the risks of myopia-related complications, such as cataracts and glaucoma, still remain.
Can presbyopia offset myopia?
Myopia does not get offset by presbyopia. The myopia will still be present, and the only reason it may not be as noticeable is if the presbyopia degree happens to match the myopia degree.
Can wearing glasses correct the myopia?
Wearing glasses can correct the vision, but it does not prevent or slow down the progression of myopia. Proper eye care habits are also essential.
Wearing glasses with a lower prescription can slow down myopia progression?
This is a common misconception. Wearing glasses with an insufficient prescription can worsen myopia. It is important to undergo eye examinations and wear the appropriate corrective lenses regularly.
Is early-onset myopia just "pseudo-myopia"?
Pseudo-myopia refers to a temporary form of myopia caused by the improper focusing of the eye muscles after prolonged near-work. The myopia experienced by young children should not be dismissed as pseudo-myopia.
Avoiding electronic screen products can prevent myopia?
In addition to prolonged exposure to electronic screen products, near-work activities such as reading, painting, and writing can also contribute to the progression of myopia. Lack of sufficient rest and outdoor activities can also exacerbate myopia.
Prevention
Proper Eye Care:
- Keep a distance of at least 30cm between the eyes and the books.
- Do not read without adequate lighting.
- Take a rest for 20 to 30 seconds after every 20 to 30 minutes of screen use.
- Keep reading distance no less than 50cm from a computer screen, 40cm from a tablet or e-book, and 30cm from a smartphone.
- For students of 6 to 12 years old should limit recreational screen time to no more than two hours a day.
- For outdoor activity under sunlight, evening time is preferred.
Other Habits:
- Have a balanced diet: eat more cereal, grains, vegetables and fruits as well as a moderate amount of meat, but eat less fat.
- Eat food rich in vitamin A (e.g. tomatoes and carrots) which is good for your eyesight.
- Have vision test once a year. Wear glasses if myopia affects your academic performance or daily activities.
Reference:
1. https://www.studenthealth.gov.hk/tc_chi/health/health_ev/health_ev_nea.html
2. https://myopiainstitute.org/wp-content/uploads/2020/10/Myopia_report_020517.pdf
