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Presbyopia - Dictionary Definition and Overview |
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Presbyopia : (noun)
1: farsightedness resulting from a reduced ability to focus
caused by loss of elasticity of the crystalline lens with
age
Based on WordNet 2.0
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Presbyopia : \Pres`by*o"pi*a\[NL., from Gr. ? old, n., an old man
_ ?, ?, the eye.] (Med.)
A defect of vision consequent upon advancing age. It is due
to rigidity of the crystalline lens, which produces
difficulty of accommodation and recession of the near point
of vision, so that objects very near the eyes can not be seen
distinctly without the use of convex glasses. Called also
presbytia.
Based on Webster's Revised Unabridged Dictionary
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Presbyopia : Presbyopia: The loss of the eye's ability to change focus to see near objects. The reasons for this loss of the power of accommodation are not yet fully known. It is conventionally said to be
due to the lens becoming less elastic with time.
Presbyopia is associated with aging. It occurs in everyone. The first sign is often the need to hold reading material farther away.
The lens of the eye and the muscle that surrounds it are like atomic clocks, slowly ticking with such precision that a person's age can be determined by measuring their ability to focus close up.
Children can normally focus on objects an inch or so (a few centimeters) from their eyes. They lose that ability as teenagers. By age 45 or so, when the eyes can focus no closer than a yard (a
meter) or two away, almost everyone needs glasses to read a newspaper or thread a needle.
The word "presbyopia" comes from the Greek for "elderly vision."
Based on Webster's Revised Unabridged Dictionary (1913)
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