ABO NOCE Basic Opticianry Applying Prentice's Rule 3

Question 1

A patient's right eye requires 1.50Δ base in. The lens power is +3.00 D. In which direction and how far should the optical center be decentered?

Accepted Answer

5 mm nasally

Answer

d = 1.50/3.00 = 0.5 cm = 5 mm; for a plus lens, decentering the OC nasally places the eye temporal to the OC, inducing base-in prism.

Question 2

An optician finds 1.80Δ of induced prism in a -4.50 D lens. How far is the OC displaced from the MRP?

Accepted Answer

4 mm

Answer

d = 1.80/4.50 = 0.4 cm = 4 mm.

Question 3

Which of the following correctly states Prentice's Rule?

Accepted Answer

Δ = P × d (d in cm)

Answer

Prentice's Rule is Δ = P × d, where d must be in centimeters.

Question 4

A +6.00 D lens is positioned so the patient looks through a point 3 mm above the optical center. What is the induced prism and base direction?

Accepted Answer

1.80Δ base up

Answer

Δ = 6.00 × 0.3 = 1.80Δ; looking above the OC of a plus lens induces base-up prism because the base is toward the OC.

Question 5

OD is +2.00 D decentered 4 mm temporally; OS is +2.00 D decentered 4 mm temporally. What is the total horizontal prismatic imbalance between the eyes?

Accepted Answer

1.60Δ

Answer

Each eye: Δ = 2.00 × 0.4 = 0.80Δ; OD temporal decentration = base out OD; OS temporal decentration = base out OS; both base out means they compound, creating 1.60Δ total imbalance for vergence.

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Practice Test

ABO NOCE Basic Opticianry Applying Prentice's Rule 3