ABO NOCE Ultimate Exam
Question 1. Which law explains the change in direction of light as it passes from air into a higher-index
material?
A) Snell’s Law
B) Brewster’s Angle
C) Huygens’ Principle
D) Fresnel Equations
Answer: A
Explanation: Snell’s Law (n₁ sin θ₁ = n₂ sin θ₂) defines refraction when light moves between media of
different refractive indices.
Question 2. The refractive index of polycarbonate is approximately 1.586. What is the speed of light in
polycarbonate?
A) 1.89 × 10⁸ m/s
B) 2.00 × 10⁸ m/s
C) 1.89 × 10⁹ m/s
D) 2.00 × 10⁹ m/s
Answer: A
Explanation: Speed = c / n; c = 3.00 × 10⁸ m/s; 3.00×10⁸ / 1.586 ≈ 1.89×10⁸ m/s.
Question 3. Which region of the electromagnetic spectrum is most responsible for cataract formation?
A) Ultraviolet (UV-A)
B) Visible green
C) Infrared (IR-B)
D) Microwave
Answer: A
Explanation: UV-A (320-400 nm) penetrates the cornea and lens, causing protein damage that
accelerates cataract development.
Question 4. A prism has a base thickness of 5 mm and a base curve of 6.00 D. Using Prentice’s Rule
(P = c × D), what prism is induced at the optical centre if the decentration is 2 mm?
, ABO NOCE Ultimate Exam
A) 0.10 Δ base down
B) 0.12 Δ base up
C) 0.30 Δ base down
D) 0.12 Δ base up
Answer: D
Explanation: P = c × D = 0.002 m × 6 D = 0.012 Δ. Positive value indicates base up for a plus lens.
Question 5. When two prisms of equal power are oriented with bases opposite each other, the resulting
effect is:
A) Compounding
B) Resolving
C) Neutralizing
D) Inverting
Answer: C
Explanation: Opposing equal prisms cancel each other, producing a net zero prism (neutralization).
Question 6. A prescription reads –2.50 – 1.00 × 180. After transposition to plus cylinder form, what is the
result?
A) –1.50 + 1.00 × 090
B) –3.50 + 1.00 × 090
C) –1.50 + 1.00 × 180
D) –3.50 + 1.00 × 180
Answer: B
Explanation: Add sphere and cylinder: –2.50 + (–1.00) = –3.50; change sign of cylinder: +1.00; axis
rotates 90°: 180 → 090.
Question 7. The spherical equivalent of a prescription –4.00 – 2.00 × 090 is:
A) –5.00 D
B) –4.00 D
C) –5.50 D
, ABO NOCE Ultimate Exam
D) –6.00 D
Answer: A
Explanation: SE = sphere + (cylinder / 2) = –4.00 + (–2.) = –5.00 D.
Question 8. According to Vogel’s Rule, the base curve for a single-vision lens for a 30-year-old patient
with a 40 mm frame width should be closest to:
A) +4.00 D
B) +6.00 D
C) +8.00 D
D) +10.00 D
Answer: B
Explanation: Vogel’s Rule selects a base curve that is roughly half the patient’s total dioptric power; a
moderate +6.00 D is typical for average prescriptions in a 40 mm frame.
Question 9. Sagittal depth of a lens increases when:
A) Diameter decreases, curvature stays constant
B) Diameter increases, curvature stays constant
C) Both diameter and curvature decrease
D) Both diameter and curvature increase
Answer: B
Explanation: Larger diameters require more material to maintain the same curvature, increasing sagittal
depth.
Question 10. Which lens material has the highest Abbe value, indicating the least chromatic aberration?
A) Polycarbonate (Abbe ≈ 30)
B) Trivex (Abbe ≈ 45)
C) High-index 1.74 (Abbe ≈ 20)
D) CR-39 (Abbe ≈ 58)
Answer: D
Explanation: CR-39’s Abbe value (~58) is higher than the others, giving the best chromatic performance.
, ABO NOCE Ultimate Exam
Question 11. The cornea consists of how many layers?
A) 3
B) 5
C) 7
D) 9
Answer: B
Explanation: The cornea has five layers: epithelium, Bowman's layer, stroma, Descemet’s membrane,
and endothelium.
Question 12. Which part of the uvea contains the pigment-producing melanocytes that absorb stray
light?
A) Iris
B) Ciliary body
C) Choroid
D) Retina
Answer: C
Explanation: The choroid is a vascular, pigmented layer that reduces intra-ocular light scatter.
Question 13. Rod photoreceptors are most sensitive to:
A) Red light
B) Blue light
C) Low-intensity, scotopic conditions
D) High-contrast colour vision
Answer: C
Explanation: Rods function in dim light (scotopic vision) and are not colour sensitive.
Question 14. In presbyopia, the loss of accommodation is primarily due to:
A) Decreased corneal curvature
Question 1. Which law explains the change in direction of light as it passes from air into a higher-index
material?
A) Snell’s Law
B) Brewster’s Angle
C) Huygens’ Principle
D) Fresnel Equations
Answer: A
Explanation: Snell’s Law (n₁ sin θ₁ = n₂ sin θ₂) defines refraction when light moves between media of
different refractive indices.
Question 2. The refractive index of polycarbonate is approximately 1.586. What is the speed of light in
polycarbonate?
A) 1.89 × 10⁸ m/s
B) 2.00 × 10⁸ m/s
C) 1.89 × 10⁹ m/s
D) 2.00 × 10⁹ m/s
Answer: A
Explanation: Speed = c / n; c = 3.00 × 10⁸ m/s; 3.00×10⁸ / 1.586 ≈ 1.89×10⁸ m/s.
Question 3. Which region of the electromagnetic spectrum is most responsible for cataract formation?
A) Ultraviolet (UV-A)
B) Visible green
C) Infrared (IR-B)
D) Microwave
Answer: A
Explanation: UV-A (320-400 nm) penetrates the cornea and lens, causing protein damage that
accelerates cataract development.
Question 4. A prism has a base thickness of 5 mm and a base curve of 6.00 D. Using Prentice’s Rule
(P = c × D), what prism is induced at the optical centre if the decentration is 2 mm?
, ABO NOCE Ultimate Exam
A) 0.10 Δ base down
B) 0.12 Δ base up
C) 0.30 Δ base down
D) 0.12 Δ base up
Answer: D
Explanation: P = c × D = 0.002 m × 6 D = 0.012 Δ. Positive value indicates base up for a plus lens.
Question 5. When two prisms of equal power are oriented with bases opposite each other, the resulting
effect is:
A) Compounding
B) Resolving
C) Neutralizing
D) Inverting
Answer: C
Explanation: Opposing equal prisms cancel each other, producing a net zero prism (neutralization).
Question 6. A prescription reads –2.50 – 1.00 × 180. After transposition to plus cylinder form, what is the
result?
A) –1.50 + 1.00 × 090
B) –3.50 + 1.00 × 090
C) –1.50 + 1.00 × 180
D) –3.50 + 1.00 × 180
Answer: B
Explanation: Add sphere and cylinder: –2.50 + (–1.00) = –3.50; change sign of cylinder: +1.00; axis
rotates 90°: 180 → 090.
Question 7. The spherical equivalent of a prescription –4.00 – 2.00 × 090 is:
A) –5.00 D
B) –4.00 D
C) –5.50 D
, ABO NOCE Ultimate Exam
D) –6.00 D
Answer: A
Explanation: SE = sphere + (cylinder / 2) = –4.00 + (–2.) = –5.00 D.
Question 8. According to Vogel’s Rule, the base curve for a single-vision lens for a 30-year-old patient
with a 40 mm frame width should be closest to:
A) +4.00 D
B) +6.00 D
C) +8.00 D
D) +10.00 D
Answer: B
Explanation: Vogel’s Rule selects a base curve that is roughly half the patient’s total dioptric power; a
moderate +6.00 D is typical for average prescriptions in a 40 mm frame.
Question 9. Sagittal depth of a lens increases when:
A) Diameter decreases, curvature stays constant
B) Diameter increases, curvature stays constant
C) Both diameter and curvature decrease
D) Both diameter and curvature increase
Answer: B
Explanation: Larger diameters require more material to maintain the same curvature, increasing sagittal
depth.
Question 10. Which lens material has the highest Abbe value, indicating the least chromatic aberration?
A) Polycarbonate (Abbe ≈ 30)
B) Trivex (Abbe ≈ 45)
C) High-index 1.74 (Abbe ≈ 20)
D) CR-39 (Abbe ≈ 58)
Answer: D
Explanation: CR-39’s Abbe value (~58) is higher than the others, giving the best chromatic performance.
, ABO NOCE Ultimate Exam
Question 11. The cornea consists of how many layers?
A) 3
B) 5
C) 7
D) 9
Answer: B
Explanation: The cornea has five layers: epithelium, Bowman's layer, stroma, Descemet’s membrane,
and endothelium.
Question 12. Which part of the uvea contains the pigment-producing melanocytes that absorb stray
light?
A) Iris
B) Ciliary body
C) Choroid
D) Retina
Answer: C
Explanation: The choroid is a vascular, pigmented layer that reduces intra-ocular light scatter.
Question 13. Rod photoreceptors are most sensitive to:
A) Red light
B) Blue light
C) Low-intensity, scotopic conditions
D) High-contrast colour vision
Answer: C
Explanation: Rods function in dim light (scotopic vision) and are not colour sensitive.
Question 14. In presbyopia, the loss of accommodation is primarily due to:
A) Decreased corneal curvature
