Define the following terms:
(a) myopia:
(b) hyperopia:
(c) presbyopia:
(a) myopia: nearsightedness that occurs when the vertical axis of the eyeball is shorter than the horizontal axis or when ciliary muscle contracts too strongly. Images of distant objects are focused in front of the retina instead of on it.
(b) hyperopia: farsightedness that occurs when the horizontal axis of the eyeball is shorter than the vertical axis, so close images are focused behind the retina, not on it.
(c) presbyopia: condition where lens becomes more inelastic with age, requiring an object to be held farther and farther from the eye in order to focus on it.
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Fill in the blank(s) with the appropriate word(s).
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