Myopia, nearsightedness, is a common eye condition. If you are nearsighted, you can see objects near to you clearly, but objects farther away are blurry. It occurs when the shape of your eye causes light rays to bend incorrectly – the light rays focus at a point in front of the retina, rather than directly on its surface.
Typically, if you have myopia – nearsightedness, you will have difficulty seeing distant objects clearly, but you will have no trouble seeing at closer distances. Activities such as working on the computer or reading a book will not be a challenge however, reading a road sign may be difficult. Symptoms of myopia may include headaches, squinting or eye strain.
Myopia occurs when the eyeball is too long relative to the focusing power of the cornea and the lens of the eye, or the cornea or lens is too curved relative to the length of the eyeball. Sometimes the cause is a combination of these factors. As the eye grows through childhood, myopia usually develops in school-age children and adolescents. Additionally, genetic factors may contribute to the development of myopia.
For people with nearsightedness, the first number “sphere” in the glasses prescription is preceded with a minus sign. The higher the number, the less far away you are able to see clearly. The most common ways to correct myopia are with glasses, contact lenses and refractive surgery. The degree of your myopia determines if you need to wear glasses or contact lenses all the time, or only when you need clear distance vision,such as when you are driving or watching a movie.
Myopia is the most common refractive error. There has been an increased prevalence of myopia globally in recent years. In the United States and Europe, approximately half of the young adults are myopic. The prevalence has doubled in the past 50 years. In China, 90% of teenagers and young adults suffer from myopia. It is estimated that one-third of the world’s population, 2.5 billion people, could be diagnosed with myopia by the end of this decade. The reason for this ”myopia-epidemic” is unknown, but many specialists believe it is owing to the increasing hours of screen time on tablets and computers, which leads to eye fatigue.