Signs and Symptoms
Blindness is defined by the World Health Organization as vision in a person's best eye of less than 20/500 or a visual field of less than 10 degrees. This definition was set in 1972 and there is ongoing discussion on if it should be altered somewhat.
Read more about this topic: Blind People
Famous quotes containing the words signs and/or symptoms:
“[Christianity] endeavors equally to establish these two things: that God has set up in the Church visible signs to make himself known to those who should seek him sincerely, and that he has nevertheless so disguised them that he will only be perceived by those who seek him with all their heart.”
—Blaise Pascal (1623–1662)
“Social movements are at once the symptoms and the instruments of progress. Ignore them and statesmanship is irrelevant; fail to use them and it is weak.”
—Walter Lippmann (1889–1974)