Acuity test, visual: This test measures how well you see
at various distances. It is the familiar eye chart test.
The eye chart itself -- the usual one is called Snellen's chart
-- is imprinted with block letters that line-by-line decrease in
size, corresponding to the distance at which that line of letters is
normally visible.
The letters on Snellen's chart are, not surprisingly, called
Snellen's test type. Each block letter is quite scientific in design
(so that at the appropriate distance the letter subtends a visual
angle of 5 degrees and each component part subtends an angle of 1
minute).
The chart and the letters are named for a 19th-century Dutch
ophthalmologist Hermann Snellen (1834-1908) who came up with them as
a test of visual acuity. Visual acuity refers to the clarity or
clearness of the vision, a measure of how well a person sees. The
word "acuity" comes from the Latin "acuitas" = sharpness.
at various distances. It is the familiar eye chart test.
The eye chart itself -- the usual one is called Snellen's chart
-- is imprinted with block letters that line-by-line decrease in
size, corresponding to the distance at which that line of letters is
normally visible.
The letters on Snellen's chart are, not surprisingly, called
Snellen's test type. Each block letter is quite scientific in design
(so that at the appropriate distance the letter subtends a visual
angle of 5 degrees and each component part subtends an angle of 1
minute).
The chart and the letters are named for a 19th-century Dutch
ophthalmologist Hermann Snellen (1834-1908) who came up with them as
a test of visual acuity. Visual acuity refers to the clarity or
clearness of the vision, a measure of how well a person sees. The
word "acuity" comes from the Latin "acuitas" = sharpness.
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