ABO PRACTICAL UPDATED EXAM -
MASTER LEVEL QUESTIONS AND
ANSWERS 100% VERIFIED. JUST
RELEASED
1. Using Prentice’s Rule, calculate the amount of induced prism for a patient wearing a -6.00
D lens when they are looking 5mm away from the optical center.
A. 0.30 prism diopters
B. 1.20 prism diopters
C. 30.00 prism diopters
D. 3.00 prism diopters
Answer: D
Conceptual Explanation: Prentice’s Rule states P = c x F, where P is prism diopters, c is
decentration in centimeters, and F is lens power. P = 0.5cm * 6.00D = 3.00^.
2. A patient is fitted with a +12.00 D lens at a vertex distance of 14mm. If the frame is moved
to a vertex distance of 10mm, what is the effective power of the lens in the new position?
A. +11.45 D
,B. +11.00 D
C. +12.61 D
D. +13.12 D
Answer: C
Conceptual Explanation: Moving a plus lens closer to the eye decreases its effective
power, requiring an increase in the compensated power. Fe = F / (1 - dF). d = 0.004m. Fe =
12 / (1 - 0.004*12) = .952 = +12.605 D.
3. Which material has the highest Abbe value, indicating the lowest amount of chromatic
aberration?
A. Polycarbonate
B. High Index 1.67
C. Crown Glass
D. Trivex
Answer: C
Conceptual Explanation: Crown glass has an Abbe value of approximately 58-59, the
highest among common lens materials, meaning it has the least chromatic dispersion.
4. According to ANSI Z80.1-2020 standards, what is the allowable tolerance for a lens with a
cylinder power of -0.75 D?
A. +/- 0.13 D
, B. +/- 0.12 D
C. +/- 0.15 D
D. +/- 0.25 D
Answer: A
Conceptual Explanation: For cylinder powers up to 2.00 D, the ANSI Z80.1 tolerance is +/-
0.13 D.
5. A lens has a front curve of +6.50 D and a back curve of -8.75 D. What is the nominal power
of the lens?
A. +2.25 D
B. -2.25 D
C. -15.25 D
D. +1.25 D
Answer: B
Conceptual Explanation: Nominal power is the sum of the front and back surface powers:
+6.50 + (-8.75) = -2.25 D.
6. In the boxing system, what does the ‘ED’ measurement represent?
A. The vertical height of the lens
B. The distance between the lenses
MASTER LEVEL QUESTIONS AND
ANSWERS 100% VERIFIED. JUST
RELEASED
1. Using Prentice’s Rule, calculate the amount of induced prism for a patient wearing a -6.00
D lens when they are looking 5mm away from the optical center.
A. 0.30 prism diopters
B. 1.20 prism diopters
C. 30.00 prism diopters
D. 3.00 prism diopters
Answer: D
Conceptual Explanation: Prentice’s Rule states P = c x F, where P is prism diopters, c is
decentration in centimeters, and F is lens power. P = 0.5cm * 6.00D = 3.00^.
2. A patient is fitted with a +12.00 D lens at a vertex distance of 14mm. If the frame is moved
to a vertex distance of 10mm, what is the effective power of the lens in the new position?
A. +11.45 D
,B. +11.00 D
C. +12.61 D
D. +13.12 D
Answer: C
Conceptual Explanation: Moving a plus lens closer to the eye decreases its effective
power, requiring an increase in the compensated power. Fe = F / (1 - dF). d = 0.004m. Fe =
12 / (1 - 0.004*12) = .952 = +12.605 D.
3. Which material has the highest Abbe value, indicating the lowest amount of chromatic
aberration?
A. Polycarbonate
B. High Index 1.67
C. Crown Glass
D. Trivex
Answer: C
Conceptual Explanation: Crown glass has an Abbe value of approximately 58-59, the
highest among common lens materials, meaning it has the least chromatic dispersion.
4. According to ANSI Z80.1-2020 standards, what is the allowable tolerance for a lens with a
cylinder power of -0.75 D?
A. +/- 0.13 D
, B. +/- 0.12 D
C. +/- 0.15 D
D. +/- 0.25 D
Answer: A
Conceptual Explanation: For cylinder powers up to 2.00 D, the ANSI Z80.1 tolerance is +/-
0.13 D.
5. A lens has a front curve of +6.50 D and a back curve of -8.75 D. What is the nominal power
of the lens?
A. +2.25 D
B. -2.25 D
C. -15.25 D
D. +1.25 D
Answer: B
Conceptual Explanation: Nominal power is the sum of the front and back surface powers:
+6.50 + (-8.75) = -2.25 D.
6. In the boxing system, what does the ‘ED’ measurement represent?
A. The vertical height of the lens
B. The distance between the lenses
