Ophthalmic Optics 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 flashcards as text
According to Prentice's Rule, a lens of +2.00 D with the optical center decentered 5 mm will produce how many prism diopters?
Answer: 1.0 Δ
Prentice's Rule: Prism (Δ) = Power (D) × Decentration (cm) = 2.00 × 0.5 cm = 1.0 Δ.
An object is placed 33 cm in front of a +4.00 D lens. Where does the image form?
Answer: 100 cm behind the lens
Incoming vergence U = -1/0.33 = -3.00 D; V = P + U = 4.00 + (-3.00) = +1.00 D; image distance = 1/1.00 = 1.0 m = 100 cm behind the lens.
What is the dioptric power of a surface with a radius of curvature of 0.10 m separating air (n=1.0) from glass (n=1.5)?
Answer: +5.00 D
Surface power = (n2 - n1) / r = (1.5 - 1.0) / 0.10 = 0.5 / 0.10 = +5.00 D.
When transposing +2.00 -3.00 x 045 to plus-cylinder form, the result is:
Answer: -1.00 +3.00 x 135
To transpose: new sphere = algebraic sum (+2.00 - 3.00 = -1.00); change cylinder sign (+3.00); rotate axis 90° (045 + 90 = 135°), giving -1.00 +3.00 x 135.
What property of light determines its color as perceived by the human eye?
Answer: Wavelength
The perceived color of light is determined by its wavelength, with visible light ranging from approximately 380 nm (violet) to 780 nm (red).
The secondary focal point of a converging lens is located:
Answer: On the opposite side from the incoming light
The secondary (rear) focal point of a converging (plus) lens is where parallel rays from the front converge, located on the opposite side from the incoming light.
Which of the following best describes a toric lens surface?
Answer: A surface with two different principal radii of curvature at 90° to each other
A toric surface has two principal meridians of different curvature oriented 90° apart, which is what creates the cylinder (astigmatic) correction.