Vision Impairment (or “visual impairment”) is vision loss (of a person) to such a degree as to qualify as an additional support need through a significant limitation of visual capability resulting from either disease, trauma, or congenital or degenerative conditions that cannot be corrected by conventional means, such as refractive correction, medication, or surgery.
Source: http://en.wikipedia.org/wiki/Disabilities#Vision_impairment
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