The
blue "standardization bar" must be measured in centimeters
on your computer screen or printout. You should then stand
in a position back from your computer screen so that your
eye is this same number of feet from the screen. i.e. if the
blue bar measures 9 1/2 centimeters in length, you should
stand back so that your eye is 9 1/2 feet from the screen.
Vision
testing should be performed on each eye separately, wearing
distance eyeglasses if required. There are six lines on the
screen, you should note the last line number in which you
can read most (50-75%) of the letters.
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The
middle letter of the top line is equivalent to 20/200. A person
unable to read this letter with best eyeglass correction is
considered legally blind.
The "T" and
the "B" on the top line are equivalent to 20/100.
The second line is 20/50. Best corrected acuity in the range
between 20/50 and 20/100 is considered disabling in occupations
which require work with numbers or extensive reading.
The
third line is equivalent to 20/40, it is the "driver's
test" line. You must be able to read most of the letters
on this line in order to obtain an unrestricted drivers license
in most states including Massachusetts.
The
bottom three lines represent 20/30, 20/20 and 20/10. These
are considered to be "normal vision" with the 20/20
line being the traditional normal vision line. It is generally
felt that the maximum visual acuity of the eye is around 20/15
or 20/16. This means that if you are able to read the bottom
line, you are probably a good guesser.
This
vision test can only be considered a screening test. A variety
of factors such as lighting, glare, monitor quality may have
an effect on the results of this test. |
