The number of people with myopia has been steadily increasing over the last decade. The World Health Organization projected that half of the world’s population will be myopic by 2050. Today Singapore is ‘the capital of myopia’ and more than 80% of the young adults are myopic.
Myopia is also called short-sightedness and near-sightedness. Someone who is myopic cannot see distant objects clearly, while the near vision may still be good. In a normal eye, light rays enter the eye through the cornea, the clear structure in the front of the eye. The cornea bends the light rays, and they are further focused by the lens onto the retina, the light-sensitive tissue at the back of the eye.
In myopia, the light entering the eye is focused in front of the retina rather than on the retina, resulting in blurry vision. This happens because either the cornea is too curved, the lens is too thick or the eyeball is too long. The majority of childhood myopia occurs because the eyeball grows too long. Children with myopia will have difficulty seeing the whiteboard in school and will need spectacles to see clearly.
The exact cause of myopia is unknown, but there is evidence that both genetic and environmental factors are at play. If one or both parents are myopic, their children will also have a higher risk of developing myopia. Children who spend a lot of time reading, playing games on their mobile devices or doing other intense near visual work indoors are also more likely to develop myopia.
In some children, myopia can progress rapidly, resulting in a worsening of vision in just a few months. This can affect the child’s performance both at school and in sports. Myopia progression also increases the risk of getting eye diseases. This is called pathological myopia. Pathological myopia increases the risk of cataracts and glaucoma. It also increases the risk of and retinal diseases:
When the eyeball is longer than normal, the retina is stretched over a much larger area. This thinner retina is more susceptible to getting holes and tears. Fluid can enter through these tears and lift the retina off, causing a retinal detachment.
The central part of the retina, called the macula, is also stretched very thin in a long myopic eye. This thin macula is susceptible to degeneration or premature aging, a condition called myopic macular degeneration. This affects the fine central vision, which is important for reading and driving.
Hence, a person with high myopia should have regular eye examinations. The lengthening of the eyeball associated with increasing myopia is an irreversible condition. It is important to control myopia progression early, so as to prevent the eye diseases associated with pathological myopia.
When myopia exceeds 6 dioptres, the risk of blinding eye diseases is higher. Unfortunately, there is no cure for myopia as the condition is irreversible once the eyeball is elongated and stretched. Even when refractive procedures are performed so that spectacles are no longer required, the risk of eye diseases associated with pathologic myopia remains. Hence, it is important to prevent myopia or slow down its progression so that the eyeball does not become too long.
Here are some ways to prevent and control myopia:
Spending two hours each day outdoors protects against the onset of myopia. Exposure to sunlight is thought to slow down or prevent the abnormal growth of the eye. Being outdoors also encourages your child to look further into the distance.
Examples of near work include reading, using the computer, and playing games on mobile devices. Minimise unnecessary screen time, especially if it is not essential for your child’s education.
Take a vision break every 20 minutes, look at something 20 feet away for at least 20 seconds.
If your child’s myopia is still increasing rapidly despite these lifestyle changes, discuss with your eye doctor whether further treatment is required.
Studies have shown that atropine eye drops can reduce myopia progression. However, atropine has some side effects, including pupil dilation. This makes the child more sensitive to sunlight. It also interferes with the child’s ability to read, hence bifocal glasses may be required when atropine is prescribed. In recent studies, lower doses of atropine have been shown to be effective, with less pupil dilation and less impairment of near vision.
Certain types of spectacles lenses and contact lenses have also been shown to slow myopia progression. If you are considering contact lenses for your child, do ensure that the lenses are carefully cleaned, as poor hygiene can predispose to blinding infections.