astig·ma·tism /əˈstɪgməˌtɪzəm/
散光
astig·ma·tism /əˈstɪgməˌtɪzəm/ 名詞
散光
A·stig·ma·tism n. Med. & Opt. A defect of the eye or of a lens, in consequence of which the rays derived from one point are not brought to a single focal point, thus causing imperfect images or indistinctness of vision.
Note: ☞ The term is applied especially to the defect causing images of lines having a certain direction to be indistinct, or imperfectly seen, while those of lines transverse to the former are distinct, or clearly seen.
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astigmatism
n 1: (ophthalmology) impaired eyesight resulting usually from
irregular conformation of the cornea [syn: astigmia]
2: (optics) defect in an optical system in which light rays
from a single point fail to converge in a single focal
point [syn: astigmia] [ant: stigmatism]