ABO NOCE Basic Opticianry Applying Prentice's Rule 4

Question 1

A compound lens is -3.00 -1.00 × 180. At a point 5 mm below the optical center, what power is used to calculate vertical prism?

Accepted Answer

-4.00 D

Answer

With the cylinder axis at 180°, the cylinder acts fully in the 90° (vertical) meridian, so vertical power = -3.00 + (-1.00) = -4.00 D.

Question 2

Per ANSI Z80.1, what is the maximum allowable induced prism at the MRP for a single-vision lens with power greater than ±3.375 D?

Accepted Answer

0.67Δ

Answer

ANSI Z80.1 allows a maximum of 0.67Δ at the MRP for lenses stronger than ±3.375 D due to greater sensitivity to OC displacement.

Question 3

A frame's distance between boxing centers is 70 mm. Patient binocular PD is 62 mm. Lens power is -2.00 D; decentration is split equally. What prism is induced per eye?

Accepted Answer

0.80Δ

Answer

Total decentration = 70 - 62 = 8 mm; per eye = 4 mm = 0.4 cm; Δ = 2.00 × 0.4 = 0.80Δ per eye.

Question 4

Which of the following produces the MOST induced prism?

Accepted Answer

-3.00 D decentered 5 mm (1.50Δ)

Answer

Δ = 3.00 × 0.5 = 1.50Δ, which is greater than any other option listed.

Question 5

A patient wears OD +4.00 D and OS plano. The OD is decentered 4 mm outward. How much horizontal prism imbalance exists between the two eyes?

Accepted Answer

1.60Δ

Answer

OD: Δ = 4.00 × 0.4 = 1.60Δ; plano OS produces 0Δ regardless of decentration; total imbalance = 1.60Δ.

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Applying Prentice's Rule 4