Myopia, commonly known as nearsightedness, is a vision condition where distant objects appear blurry while close-up objects remain clear. This occurs when the eyeball grows too long or the cornea has an irregular shape, causing light to focus in front of the retina instead of directly on it. High myopia represents a more severe form of this condition in children, and it is becoming an increasing concern globally, with projections suggesting that half of the world’s population may have myopia by 2050.
What is High Myopia in Children
High myopia in children is defined as nearsightedness requiring a correction of -6.00 diopters or higher, or an axial length greater than 26.5mm. Myopia often begins in childhood, and the earlier it develops, the more likely it is to progress to a high level, potentially continuing to worsen into the late teens or early twenties.
Parents might observe several signs and symptoms in a child with high myopia, such as frequent squinting, difficulty seeing distant objects like a whiteboard at school, or needing to sit very close to screens or books. Diagnosing high myopia involves comprehensive eye exams performed by an optometrist or ophthalmologist for early detection and management. These examinations can include special tests to measure the degree of myopia and the eye’s axial length.
Why Children Develop High Myopia
The development of high myopia in children is influenced by a combination of genetic predisposition and environmental factors. Genetic factors play a considerable role; if one parent has myopia, a child has approximately a 1 in 3 chance of developing it, and this risk increases to about 1 in 2 if both parents are nearsighted. The heritability of axial length, which directly impacts myopia, has been estimated to be between 40% and 94%.
Environmental factors also contribute significantly to the onset and progression of myopia. Increased near work activities, such as prolonged screen time on digital devices or extensive reading without breaks, can accelerate myopia progression, especially in children who are genetically predisposed. Insufficient time spent outdoors in natural light is associated with a higher risk of myopia development and progression. Natural light exposure is thought to stimulate dopamine release in the retina, which can inhibit excessive eye growth.
Treating and Managing High Myopia
Correcting vision in children with high myopia typically involves prescription eyeglasses or contact lenses, which work by changing how light enters the eye to focus images clearly on the retina. Standard single-vision lenses correct blurry vision but do not slow the progression of myopia. Therefore, specific myopia control treatments are often recommended to manage the condition and reduce its worsening over time.
Low-dose atropine eye drops are a common pharmacological intervention, typically used for children between 5 and 18 years old, applied nightly to slow eye elongation. Orthokeratology (Ortho-K) lenses offer another approach; these rigid contact lenses are worn overnight to temporarily reshape the cornea, improving daytime vision without glasses or contacts. Ortho-K has been shown to slow myopia progression by up to 50% or more in children and teens.
Multifocal contact lenses or specialized glasses are also used for myopia control. These lenses feature different areas of focus, with the center correcting distant vision and the outer portions blurring peripheral vision, which is thought to slow eye growth. Specialized spectacle lenses can help control myopia progression by at least 50% compared to single-vision lenses. Combining treatments, such as low-dose atropine with multifocal contact lenses, has shown promising results in some studies, leading to a greater decrease in myopia progression.
Potential Complications of High Myopia
High myopia, if not properly managed, can lead to several serious eye health complications. The excessive elongation of the eyeball stretches and thins the retina and other ocular tissues, making them more vulnerable to damage.
Retinal detachment is a complication where the retina separates from the back of the eye, potentially causing permanent vision loss if not treated promptly. Individuals with high myopia also face an increased risk of developing glaucoma, a condition characterized by high eye pressure that damages the optic nerve. The elongated eye shape can make fluid drainage more difficult, contributing to increased intraocular pressure.
Myopic maculopathy, a form of macular degeneration, can also occur, stressing the macula and leading to blind spots and difficulty with fine visual detail. Additionally, high myopia can contribute to the earlier formation of cataracts, which cause the eye’s natural lens to become progressively cloudy. Regular comprehensive eye examinations, typically every 6-12 months, including dilated retinal examinations, are important for early detection of these conditions.
Preventing High Myopia
Proactive measures can help reduce the risk of myopia development or slow its progression in children. Increasing outdoor time is recommended, with at least two hours of outdoor activity per day potentially lowering the risk of myopia. Spending time outdoors exposes children to natural light and encourages them to focus on distant objects, which can reduce eye strain.
Implementing the “20-20-20 rule” for screen time and near work is a practical strategy. This rule advises taking a 20-second break every 20 minutes of near work to look at something 20 feet away, allowing the eyes to rest and readjust focus. Ensuring proper lighting for reading and other close-up activities also helps prevent eye strain.