What Is Myopia?
Myopia is a progressive visual disorder that results in poor distance vision. If the myopia is severe, it will impair near vision as well. Myopia is also known as "near-sighted" or "short-sighted." In addition to weakening vision, it also changes the physical structure of the eye. It can steepen the front surface of the eye (cornea) and/or stretch the retina (axial elongation). These changes increase the risk of future eye disease (see The Dangers of Myopia). It is one of the leading causes of blindness around the world and has a direct association with retinal detachments and glaucoma.
Myopia definitely has a genetic link. However it is driven more by the environmental stress of near work such as reading, studying, computer use, hand games and the lack of outdoor time. In fact, one theory of increasing myopia is that it is our eye’s method of adapting to the demand of prolonged near work. It takes less work for a myopic person to read. That's why we call it "near-sighted". Humans before the Industrial Revolution used their eyes predominantly for distance seeing. During that period, the incidence of myopia was less than five percent. In a recent study, researchers found that myopia has increased 66 percent in the United States from 1971 to 2004 (See Health Issues: The Myopia Epidemic).
The Dangers Of Myopia
Myopia and its progressive disorders can cause abnormal or adverse ocular changes. High myopia may cause thinning and weakening of the retina (the thin membrane at the back of the eye that contains the rods and cones). Abnormal stretching or elongation of the eye may pull on the vitreous (the gel substance that fills the eye) which in turn pulls on the retina leading to its detachment. A detached retina can lead to blindness. This elongating process can also cause "lattice-like" holes to occur in the peripheral retina. These holes can allow fluid to seep under the retina-- lifting and detaching it. Again, possibly leading to a permanent loss of sight.
Moderate to high myopic people are twice as likely to develop glaucoma. (Mitchell 2000). Further, the detection of myopia is much more difficult due to the deforming of the optic nerve head as a result of ocular elongation. The optic nerve head is one of the structures closely examined for changes due to glaucoma. It is difficult to determine if the changes are due to myopic stretching or glaucoma.
Health Issues: The Myopia Epidemic
The World Health Organization (WHO) projects 2.5 billion nearsighted people by year 2020. Approximately 80% of elementary students in Singapore are myopic.
90% of college students in China are nearsighted.
The National Institutes of Health reports that in 1972, the frequency of myopia was 25% in U.S. individuals aged 12 to 54. By 2004, it had increased to 41.6%. (Roan,2010).
In 2004 approximately 26% of all people living in the U.S. and Europe were myopic.
The incidence of myopia in "hunter-gatherer" societies where children perform little near work, is about 1%.
"A Childhood Disease Worth Preventing"
by Dr. Nick Despotidis
Dr. Nicholas Despotidis warns of the potential risks of prolonged screen-time including vision loss. There can be serious repercussions when children spend hours on computer, tablet, and tiny smartphone screens.