Ophthalmic Optics and Principles 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 and Principles Questions and Answers flashcards as text
A lens has a power of +2.50 D. What is its focal length in meters?
Answer: 0.40 m
Focal length = 1 / Power, so 1 / 2.50 = 0.40 meters.
Which type of aberration causes light rays at different distances from the optical axis to focus at different points, resulting in a blurred image?
Answer: Spherical aberration
Spherical aberration occurs when peripheral rays focus at a different point than paraxial rays due to the curvature of the lens.
What is the index of refraction of a material if light travels through it at 2.0 × 10⁸ m/s (speed of light in air = 3.0 × 10⁸ m/s)?
Answer: 1.50
Index of refraction n = speed of light in air / speed of light in medium = 3.0/2.0 = 1.50.
A prism displaces an image toward which direction relative to its base?
Answer: Toward the apex
Light is refracted toward the base of a prism, so the image appears displaced toward the apex.
When light passes from a denser medium to a less dense medium at an angle exceeding the critical angle, what occurs?
Answer: Total internal reflection
Total internal reflection occurs when light exceeds the critical angle at the boundary between a denser and less dense medium.
What is the add power for a patient whose distance Rx is +1.00 D and near Rx is +3.00 D?
Answer: +2.00 D
Add power = near Rx minus distance Rx = +3.00 − (+1.00) = +2.00 D.
A cylinder lens with axis at 180° corrects which meridian of the eye?
Answer: 90° meridian
A cylinder with axis at 180° has no power in the 180° meridian and full power in the 90° meridian, correcting the 90° meridian.