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
The optical cross is a diagram used to represent:
Answer: The power in two principal meridians of a spherocylindrical lens
An optical cross shows the power in each of the two principal meridians (90° apart) of a spherocylindrical lens.
When comparing two lenses of equal power, the lens with a higher refractive index will be:
Answer: Thinner and lighter
Higher refractive index materials bend light more per unit of surface curvature, allowing flatter, thinner lens designs.
The lensometer (focimeter) measures a lens by finding the position where:
Answer: The target image is focused at a fixed reference point corresponding to a specific vergence
The lensometer neutralizes the lens power by finding the position where the target appears clear, corresponding to the vergence added by the lens.
Oblique astigmatism as a lens aberration is different from astigmatism in a prescription because it:
Answer: Is introduced by the lens itself when viewing off-axis, not from the eye's refractive error
Oblique (marginal) astigmatism is a lens aberration occurring when light passes through the peripheral zone at an angle, unrelated to the wearer's astigmatism.
The reduced eye model simplifies the eye to a single refracting surface with a refractive index of approximately:
Answer: 1.336
The reduced eye model uses a single refracting surface with the refractive index of the ocular media, approximately 1.336.
When solving for the cross-cylinder power used to refine cylinder axis and power, the examiner adds a lens whose:
Answer: Principal meridians are at 45° to the correcting cylinder axis
A Jackson Cross Cylinder (JCC) is placed with its principal meridians at 45° to the trial cylinder axis to test axis, then straddling it to test power.
Which of the following describes a plano-convex lens?
Answer: One surface is flat and the other is convex
A plano-convex lens has one flat (plano) surface with zero curvature and one convex surface, giving it positive (converging) power.