About Blindness

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Title Blindness
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(from Freebase)
Vision loss or visual loss is the absence of vision where it existed before, which can happen either acutely (i.e. abruptly) or chronically (i.e. over a long period of time). Various scales have been developed to describe the extent of vision and vision loss based on visual acuity. Early editions of the World Health Organization's ICD described a simple distinction between "legally sighted" and "legally blind". The ICD-9 released in 1979 introduced the smallest continuous scale which consisted of three tiers: normal vision, low vision, and blindness. Acute visual loss may be dramatic in presentation. It may be caused by media opacities, retinal disease, optic nerve disease, visual pathway disorders, or functional disorders, or it may be in fact an acute discovery of chronic visual loss. Opacities of the clear refractive media of the eye such as the cornea, anterior chamber, lens, and vitreous humor may cause acute visual loss as manifested by blurry vision or reduced visual acuity....
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