ABO NOCE Basic Opticianry Ophthalmic Optics Questions and Answers 4

Question 1

Prentice's Rule states that the prismatic effect at a point on a lens equals:

Accepted Answer

Decentration in cm multiplied by lens power in diopters

Answer

Prentice's Rule: P (prism diopters) = c (cm) × F (diopters), where c is decentration from optical center in centimeters.

Question 2

Which lens aberration causes the peripheral image to appear distorted in a pin-cushion or barrel shape?

Accepted Answer

Distortion

Answer

Distortion (pin-cushion or barrel) occurs because magnification varies across the lens, causing shape distortion of the image.

Question 3

The back vertex power of a lens differs most from its true power when:

Accepted Answer

The lens has high power and significant center thickness

Answer

Thick, high-powered lenses have the greatest difference between front vertex, back vertex, and true (equivalent) power.

Question 4

A lens with a +4.00 D front surface and a -2.00 D back surface has an approximate nominal power of:

Accepted Answer

+2.00 D

Answer

Nominal (thin lens) power equals F₁ + F₂ = +4.00 + (-2.00) = +2.00 D.

Question 5

Increasing the vertex distance of a plus lens relative to the eye effectively:

Accepted Answer

Decreases the effective power at the eye

Answer

Moving a plus lens farther from the eye reduces its effective converging power at the corneal plane.

ABO NOCE Basic Opticianry Practice Test