ABO NCLE UPDATED EXAMS TEST PAPER
QUESTIONS AND ANSWERS SURE A+
✔✔Compound Hyperopic Astigmatism - ✔✔This condition is no longer simple, because
not all the rays of light entering the eye meet at the same place. They all focus on a spot
beyond the retina, but some come closer to the fovea than others. Depending on the
degree of astigmatism (the degree to which the cornea is misshapen) the individual may
see objects as bent or distorted in shape as well as blurred. A prescription for a person
with a compound hyperopic astigmatism would look like one of these examples: +1.00 -
0.50 X 45 +0.50 +0.50 X 135 +2.50 -2.00 X 130 +0.50 +2.00 X 40
✔✔Mixed Astigmatism - ✔✔In the eye with mixed astigmatism some rays fall ahead of
the retina while others try to focus on a spot beyond the retina. People with mixed
astigmatism are neither nearsighted nor farsighted, but instead will have poor vision in
all areas. A prescription for a person with a mixed astigmatism would look like one of
these examples: +1.00 -2.00 X 45 -1.00 +2.00 X 135 +2.00 -2.25 X 67 -0.25 + 2.25 X
157
✔✔186,000 miles per second - ✔✔Light is a form of radiant energy. It acts as both a
particle and a wave. It travels at the fastest known speed in our universe which is
✔✔the visible spectrum lie between 400nm and 700nm. - ✔✔Red light is at the longer
end of the spectrum and violet light at the shorter end. A common acronym used to
, remember the order of colors in the visible spectrum is ROY G BIV (red, orange, yellow,
green, blue, indigo, and violet).
✔✔ultraviolet (UV) - ✔✔Just below 400nm
✔✔infrared (IR) - ✔✔just above 750nm
✔✔refraction - ✔✔As light moves from one transparent medium to another, at any angle
other than perpendicular to the material surface, the change in speed will also result in a
change in direction. This change is direction is called
✔✔index of refraction - ✔✔"n" is the notation, n tells us how much a given material will
slow down and change the direction of a ray of light passing through it. The higher the
index or "n" the thinner a lens can be and produce the same power. Common index
numbers include, 1.498, 1.523, 1.586, 1.60, 1.67, and 1.74. It is a scientific absolute
that the higher the index of refraction, the thinner a lens can be and still produce the
same diopter value. • A lens with an index of refraction of 1.74 and a power of - 6.00 will
be thinner than a lens with an index of refraction of 1.53 with the same power of - 6.00.
✔✔D = 1/f - ✔✔The formula for a diopter is this: When D is diopter, and f is the focal
length of a lens in meters. So if I know that a lens has a focal length of 0.50 meters
1/0.50 = 2 My lens diopter power is 2.00
✔✔F = 1/D - ✔✔The formula can also work the other way so that f is equal to 1/D, So if
I know that a lens is 2.00 diopters 1/2.00 = 0.50 My lens focal length will be 0.50 or half
a meter.
✔✔It's Jeopardy Time! 186,000 Miles per second - ✔✔the speed of light
✔✔1.74 - ✔✔an example of an index of refraction
✔✔D = 1/f - ✔✔the formula for diopter
✔✔400-700 nm - ✔✔range of visible light in nanometers
✔✔apex to apex or base to base - ✔✔all ophthalmic lenses are two prisms, stacked
either
✔✔meniscus lens - ✔✔term used for modern optical lenses, because its shape is like
the shape of a meniscus moon
✔✔converges - ✔✔Light passing through a plus lens
✔✔diverges - ✔✔Light passing through a minus lens
QUESTIONS AND ANSWERS SURE A+
✔✔Compound Hyperopic Astigmatism - ✔✔This condition is no longer simple, because
not all the rays of light entering the eye meet at the same place. They all focus on a spot
beyond the retina, but some come closer to the fovea than others. Depending on the
degree of astigmatism (the degree to which the cornea is misshapen) the individual may
see objects as bent or distorted in shape as well as blurred. A prescription for a person
with a compound hyperopic astigmatism would look like one of these examples: +1.00 -
0.50 X 45 +0.50 +0.50 X 135 +2.50 -2.00 X 130 +0.50 +2.00 X 40
✔✔Mixed Astigmatism - ✔✔In the eye with mixed astigmatism some rays fall ahead of
the retina while others try to focus on a spot beyond the retina. People with mixed
astigmatism are neither nearsighted nor farsighted, but instead will have poor vision in
all areas. A prescription for a person with a mixed astigmatism would look like one of
these examples: +1.00 -2.00 X 45 -1.00 +2.00 X 135 +2.00 -2.25 X 67 -0.25 + 2.25 X
157
✔✔186,000 miles per second - ✔✔Light is a form of radiant energy. It acts as both a
particle and a wave. It travels at the fastest known speed in our universe which is
✔✔the visible spectrum lie between 400nm and 700nm. - ✔✔Red light is at the longer
end of the spectrum and violet light at the shorter end. A common acronym used to
, remember the order of colors in the visible spectrum is ROY G BIV (red, orange, yellow,
green, blue, indigo, and violet).
✔✔ultraviolet (UV) - ✔✔Just below 400nm
✔✔infrared (IR) - ✔✔just above 750nm
✔✔refraction - ✔✔As light moves from one transparent medium to another, at any angle
other than perpendicular to the material surface, the change in speed will also result in a
change in direction. This change is direction is called
✔✔index of refraction - ✔✔"n" is the notation, n tells us how much a given material will
slow down and change the direction of a ray of light passing through it. The higher the
index or "n" the thinner a lens can be and produce the same power. Common index
numbers include, 1.498, 1.523, 1.586, 1.60, 1.67, and 1.74. It is a scientific absolute
that the higher the index of refraction, the thinner a lens can be and still produce the
same diopter value. • A lens with an index of refraction of 1.74 and a power of - 6.00 will
be thinner than a lens with an index of refraction of 1.53 with the same power of - 6.00.
✔✔D = 1/f - ✔✔The formula for a diopter is this: When D is diopter, and f is the focal
length of a lens in meters. So if I know that a lens has a focal length of 0.50 meters
1/0.50 = 2 My lens diopter power is 2.00
✔✔F = 1/D - ✔✔The formula can also work the other way so that f is equal to 1/D, So if
I know that a lens is 2.00 diopters 1/2.00 = 0.50 My lens focal length will be 0.50 or half
a meter.
✔✔It's Jeopardy Time! 186,000 Miles per second - ✔✔the speed of light
✔✔1.74 - ✔✔an example of an index of refraction
✔✔D = 1/f - ✔✔the formula for diopter
✔✔400-700 nm - ✔✔range of visible light in nanometers
✔✔apex to apex or base to base - ✔✔all ophthalmic lenses are two prisms, stacked
either
✔✔meniscus lens - ✔✔term used for modern optical lenses, because its shape is like
the shape of a meniscus moon
✔✔converges - ✔✔Light passing through a plus lens
✔✔diverges - ✔✔Light passing through a minus lens
