Myopia, or nearsightedness, is a vision defect that happens when one’s eyes are unable to focus the light from distant objects correctly onto the retina. Someone with myopia is able to clearly see objects that are close, but objects that are far away are blurry.
Myopia generally first arises in elementary-aged children, though it can also develop in adults. Research indicates that it is a hereditary trait – children whose parents are nearsighted are more likely to be as well. Although the inclination to acquire nearsightedness is likely inherited, the development of the condition can be affected by how one uses their eyes. For example, a person who spends a lot of time reading or who does extensive work on the computer or other close visual work may be at higher risk of developing myopia.
Myopia has become increasingly more common over the past 50 years, and it is estimated to now affect around 1.6 billion people worldwide, with numbers expected to climb to 2.5 billion by 2020, according to the Institute of Eye Research. In the United States, nearsightedness (myopia) affects nearly 30 percent of the population.
The increase in myopia cases is thought by a team of Australian researchers to be a result of more children being raised in environments where they don’t see objects far away and their eyes aren’t adapted to focus on distant objects as they develop. Global myopia cases are most prevalent in societies where children watch television and play computer games instead of playing outside, they say. In cities like Hong Kong and Tokyo, 30 to 50 percent of 12-year-old children are myopic; in the United States, it is around 20 percent for this age group.
A report published in the January issue of Optometry and Vision Science found that children with myopia spent an average of 8.3 hours per week outside and children without myopia spent an average of 12.6 hours outside. The study also found that children with myopia watched several additional hours per week of television, on average.
The researchers, from The New England College of Optometry, said that sunlight could expand the range that objects are clearly visible. The effect appeared to be similar with both active and passive outdoor activity.
Myopia symptoms and correction
Common symptoms of myopia in children include squinting to see distant objects, difficulty reading the chalkboard at school, sitting close to the television, and disinterest in playing outside.
Myopia doubles the risk of glaucoma and retinal detachment, both of which can lead to vision loss later in life.
A basic vision test will determine if an individual is nearsighted. Myopia is relatively easy to correct with contact lenses or eyeglasses. The lens bends the images that enter the eye and focuses the image properly. Depending on the severity of one’s myopia, wearers may only need to wear their lenses for certain activities. Adults can also consider laser surgery, which can only be done after the eyeball is fully developed.
Another option for treating myopia is called orthokeratology, or corneal refractive therapy. With this treatment, myopic patients wear specially designed rigid contact lenses that gradually reshape the cornea.
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