chapter 13 - magnification Flashcards
Lateral (transverse/ linear)
clinically relevant to low vision
the object if within the focal length of a plus lens thereby creates a virtual image
Size
clinically relevant to low vision
the object is made physically larger
relative distance
clinically relevant to low vision
The object is moved physically closer to the eye
angular
clinically relevant to low vision
the angle an object makes at the eye is increased
effective and conventional
clinically relevant to low vision
a manufacturer labels plus lenses so customers can compare magnifications.
clinicians convert this value to dioptric power
Spectacle
clinically relevant to Aniseikonia
a pt has anisometropia, the correcting lenses create images of different angular sizes for the 2 eyes
near print size
the detail of 1M print subtends an angle of 1 minute of arc at a viewing distance of 1m
Equivalent viewing distance
the distance at which the print subtends a sufficiently large angle to be resolved
equivalent viewing power
specify the power of plus lens whose focal length is equal to equivalent viewing distance
the rays emerging from the reading material (magnifying glass) are
a. parallel
b. diverging
c. none of the above
a. parallel
If the distance between plus magnified and add is EQUAL to the focal length of the handheld magnifier, the magnification relative to looking through the plus les magnifier with the distance RX is _____
the same
If the distance between plus magnified and add is LESS THAN the focal length of the handheld magnifier, the magnification relative to looking through the plus les magnifier with the distance RX is _____
more
If the distance between plus magnified and add is MORE THAN the focal length of the handheld magnifier, the magnification relative to looking through the plus les magnifier with the distance RX is _____
less
