Myopia
Myopia, commonly known as nearsightedness, is a visual defect characterized by the difficulty in perceiving distant objects clearly. This occurs when light entering the eye focuses in front of the retina, rather than directly on it, leading to blurred vision for faraway items. The condition is primarily caused by an elongated eyeball, with genetic factors playing a significant role, as individuals with myopic parents are more likely to develop the condition themselves. Research also suggests that prolonged eyestrain from close-up tasks, such as reading, may contribute to the development of myopia, which is more prevalent among individuals with higher education levels.
Symptoms typically begin to manifest as children age, with a notable increase in prevalence during the teenage years. While vision deterioration tends to slow in early adulthood, it can accelerate again in middle and old age, significantly affecting individuals over seventy. Treatment options for myopia primarily include wearing concave lenses to adjust the focal point of light or undergoing laser surgery to reshape the cornea. Understanding myopia can provide valuable insights into its management and the importance of regular eye examinations for maintaining visual health.
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Subject Terms
Myopia
ALSO KNOWN AS: Nearsightedness
ANATOMY OR SYSTEM AFFECTED: Eyes
DEFINITION: A visual defect that impairs the perception of distant objects
CAUSES: Genetic predisposition, prolonged eyestrain
SYMPTOMS: Impaired perception of distant objects
DURATION: Varies
TREATMENTS: Wearing concave lenses, correction through laser surgery
Causes and Symptoms
Nearsightedness (myopia) occurs when light from distant objects reaches a focal point in front of, rather than on, the retina, the photoreceptive tissue of the eye. Consequently, vision of distant objects is blurred on the retina. The primary cause of myopia is an eyeball that is too long from front to back. People whose parents have myopia are more likely to have it, indicating a genetic cause; a few studies have also shown correlations between higher testosterone levels in the womb and later incidence of myopia. Research has also found that prolonged eyestrain, especially from long periods of reading or other close work, can distort the shape of the eye. This may be one reason why more highly educated people manifest higher rates of nearsightedness than individuals with less formal education.
All children are born nearsighted; by the age of six months, however, vision begins to improve. Myopia is an uncommon problem in younger school-age children but begins to increase in prevalence as children move into their teenage years. From the twenties until the forties, the rate of visual deterioration tends to slow down. As people enter middle and old age, however, the rate of visual decline accelerates again. People past the age of seventy are fourteen times as likely to experience myopia resulting in legal blindness as those in their twenties.
Treatment and Therapy
For several centuries, nearsightedness has been corrected by the use of a concave lens, which moves the focal point of light in myopic eyes closer to the retina. The first eyeglasses, invented in late thirteenth-century Italy, had convex lenses that corrected for farsightedness (hyperopia); not until the fifteenth century did glasses with concave lenses appear. As the twentieth century drew to a close, innovative surgical approaches were developed to correct for myopia. Most of these procedures, such as laser surgery, move the focal point of light closer to the retina by changing the shape of the cornea.
Bibliography
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Turbert, David. "Nearsightedness: What Is Myopia?" American Academy of Ophthalmology, 22 Sept. 2022, www.aao.org/eye-health/diseases/myopia-nearsightedness. Accessed 3 Apr. 2024.