Ophthalmic Optics Questions and Answers Flashcards
7 cards from real ABO NOCE Basic Opticianry practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Ophthalmic Optics Questions and Answers flashcards as text
Prentice's Rule states that the prismatic effect at a point on a lens equals:
Answer: Decentration in cm multiplied by lens power in diopters
Prentice's Rule: P (prism diopters) = c (cm) × F (diopters), where c is decentration from optical center in centimeters.
Which lens aberration causes the peripheral image to appear distorted in a pin-cushion or barrel shape?
Answer: Distortion
Distortion (pin-cushion or barrel) occurs because magnification varies across the lens, causing shape distortion of the image.
The back vertex power of a lens differs most from its true power when:
Answer: The lens has high power and significant center thickness
Thick, high-powered lenses have the greatest difference between front vertex, back vertex, and true (equivalent) power.
A lens with a +4.00 D front surface and a -2.00 D back surface has an approximate nominal power of:
Answer: +2.00 D
Nominal (thin lens) power equals F₁ + F₂ = +4.00 + (-2.00) = +2.00 D.
Increasing the vertex distance of a plus lens relative to the eye effectively:
Answer: Decreases the effective power at the eye
Moving a plus lens farther from the eye reduces its effective converging power at the corneal plane.
What does the term 'transposition' mean in ophthalmic optics?
Answer: Converting a prescription from plus cylinder to minus cylinder form or vice versa
Transposition converts a prescription between plus and minus cylinder forms while maintaining the same optical effect.
An image formed by a concave (minus) lens is always:
Answer: Virtual and erect
A concave (diverging) lens always forms a virtual, erect, and diminished image on the same side as the object.