Lens Mag and Min

Question 1

what is the difference in refractive power between the two eyes called?

Answer 1

anisometropia

Question 2

what is a relative difference in size and/or shape of the ocular image called?

Answer 2

aniseikonia

Question 3

what are some possible causes of aniseikonia?

Answer 3

anatomical, inherent optic, induced

Question 4

for axial myopes, the uncorrected image size will be _____ than the image size for a normal eye

Answer 4

larger

b/c long eyeball

Question 5

for axial hyperopes, the uncorrected image size will be ____ than the image size for a normal eye

Answer 5

smaller

b/c short eyeball

Question 6

according to classic theory, you should correct axial ametropia with:

Answer 6

spectacles

Question 7

according to classic theory, you should correct refractive ametropia with:

Answer 7

contacts

Question 8

if K’s are equal, it is likely to be _____ ametropia

Answer 8

axial

Question 9

if K’s are equal to the anisometropia, it is likely to be ____ ametropia

Answer 9

refractive

Question 10

in spectacle magnification, the power factor (Mp) accounts for:

Answer 10

wearing distance and back vertex power

Question 11

in spectacle magnification, the shape factor (Ms) accounts for:

Answer 11

front surface power, center thickness, and index of refraction

Question 12

is SM < or > 1 for plus (+) lenses?

Answer 12

SM > 1

Question 13

is SM < or > 1 for minus (-) lenses?

Answer 13

SM < 1

Question 14

Ms and therefore SM increases with:

Answer 14

• increase in F1
• increase in tc
• decrease in n

Question 15

retinal image size increases with increasing ____ power

Answer 15

plus power

Question 16

retinal image size decreases with increasing ___ power

Answer 16

minus power

Question 17

“first pass method” includes what 4 selections>

Answer 17

1. frame w/ short vertex distance
2. frame with small eyesize
3. aspheric design (flattens BC)
4. high index material