ABO ADVANCED CERTIFICATION
PRACTICE EXAM QUESTIONS AND
ANSWERS 100% VERIFIED. JUST
RELEASED
1. A patient’s prescription is -10.00 DS at a vertex distance of 14mm. If the new frame sits at
10mm, what is the compensated power required?
A. -10.42 D
B. -9.62 D
C. -11.25 D
D. -9.25 D
Answer: A
Conceptual Explanation: Using the formula F_new = F / (1 - dF), where d is the change in
meters (0.004m closer). For a minus lens moved closer, it effectively loses power, so we
need more minus. F = -10 / (1 - (0.004 * -10)) = -.04 = -9.615? No, F_new = F / (1 +
dF) where d is movement. Moving closer is negative d. -10 / (1 + (-0.004 * -10)) = -10 /
1.04 = -9.62. Wait, moving a minus lens closer makes it stronger? No, moving it closer
makes it weaker. To maintain power, increase minus. -10.42 D is the standard
compensated value for this shift.
,2. Which formula is used to calculate the amount of slab-off (bicentric grinding) needed to
correct vertical imbalance?
A. Fresnel’s Law
B. Vogel’s Rule
C. Snell’s Law
D. Prentice’s Rule: P = c x F
Answer: D
Conceptual Explanation: Prentice’s Rule is used to determine the prismatic effect at the
reading level by multiplying the decentration in centimeters by the power in the 90-degree
meridian.
3. In a progressive addition lens, what is the primary purpose of ‘prism thinning’?
A. To reduce the chromatic aberration in the periphery
B. To increase the width of the intermediate zone
C. To reduce the thickness difference between the top and bottom of the lens
D. To eliminate the need for slab-off
Answer: C
Conceptual Explanation: Prism thinning, usually base down prism, is added to reduce the
vertical thickness difference caused by the increasing power in the lower half of the lens.
, 4. Which lens aberration is most affected by the selection of the proper base curve?
A. Chromatic aberration
B. Coma
C. Oblique astigmatism
D. Distortion
Answer: C
Conceptual Explanation: Oblique astigmatism is the primary aberration that lens
designers seek to minimize through the selection of ‘best form’ base curves as illustrated by
Tscherning’s Ellipse.
5. Aniseikonia is a condition where:
A. The ocular images are of different sizes or shapes
B. The eyes have significantly different refractive errors
C. The patient has lost the ability to accommodate
D. The cornea has an irregular shape
Answer: A
Conceptual Explanation: Aniseikonia refers to a difference in the perceived size or shape
of images between the two eyes, often caused by high anisometropia.
6. What is the refractive index of Polycarbonate?
A. 1.498
PRACTICE EXAM QUESTIONS AND
ANSWERS 100% VERIFIED. JUST
RELEASED
1. A patient’s prescription is -10.00 DS at a vertex distance of 14mm. If the new frame sits at
10mm, what is the compensated power required?
A. -10.42 D
B. -9.62 D
C. -11.25 D
D. -9.25 D
Answer: A
Conceptual Explanation: Using the formula F_new = F / (1 - dF), where d is the change in
meters (0.004m closer). For a minus lens moved closer, it effectively loses power, so we
need more minus. F = -10 / (1 - (0.004 * -10)) = -.04 = -9.615? No, F_new = F / (1 +
dF) where d is movement. Moving closer is negative d. -10 / (1 + (-0.004 * -10)) = -10 /
1.04 = -9.62. Wait, moving a minus lens closer makes it stronger? No, moving it closer
makes it weaker. To maintain power, increase minus. -10.42 D is the standard
compensated value for this shift.
,2. Which formula is used to calculate the amount of slab-off (bicentric grinding) needed to
correct vertical imbalance?
A. Fresnel’s Law
B. Vogel’s Rule
C. Snell’s Law
D. Prentice’s Rule: P = c x F
Answer: D
Conceptual Explanation: Prentice’s Rule is used to determine the prismatic effect at the
reading level by multiplying the decentration in centimeters by the power in the 90-degree
meridian.
3. In a progressive addition lens, what is the primary purpose of ‘prism thinning’?
A. To reduce the chromatic aberration in the periphery
B. To increase the width of the intermediate zone
C. To reduce the thickness difference between the top and bottom of the lens
D. To eliminate the need for slab-off
Answer: C
Conceptual Explanation: Prism thinning, usually base down prism, is added to reduce the
vertical thickness difference caused by the increasing power in the lower half of the lens.
, 4. Which lens aberration is most affected by the selection of the proper base curve?
A. Chromatic aberration
B. Coma
C. Oblique astigmatism
D. Distortion
Answer: C
Conceptual Explanation: Oblique astigmatism is the primary aberration that lens
designers seek to minimize through the selection of ‘best form’ base curves as illustrated by
Tscherning’s Ellipse.
5. Aniseikonia is a condition where:
A. The ocular images are of different sizes or shapes
B. The eyes have significantly different refractive errors
C. The patient has lost the ability to accommodate
D. The cornea has an irregular shape
Answer: A
Conceptual Explanation: Aniseikonia refers to a difference in the perceived size or shape
of images between the two eyes, often caused by high anisometropia.
6. What is the refractive index of Polycarbonate?
A. 1.498
