Optical Instrumentation Use Questions and Answers Flashcards
6 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 6 Optical Instrumentation Use Questions and Answers flashcards as text
When using a lensometer (lensmeter) to neutralize a lens, the mires are brought into sharp focus. For a spherocylindrical lens, in what order are the power meridians found?
Answer: The first clear focus gives the sphere power; the second clear focus gives the sphere + cylinder power
In a spherocylindrical lens, focusing the lensometer drum to the first clear set of lines gives the power in one principal meridian (sphere); rotating 90° and refocusing gives the combined power (sphere + cylinder).
The keratometer (ophthalmometer) measures which property of the cornea?
Answer: The curvature (radius of curvature) of the central anterior corneal surface
The keratometer measures the radius of curvature of the anterior corneal surface at the central 3mm zone, used for contact lens base curve selection and detecting astigmatism.
When verifying a finished lens with a lensometer, the optical center is found when:
Answer: The mire target is centered in the reticle with no prism displacement
The optical center (OC) is located at the point on the lens where the mire is centered in the reticle (no prism displacement), regardless of power reading.
What does a pupilometer measure, and what advantage does it have over a PD ruler?
Answer: It measures pupillary distance; it provides more accurate monocular PD measurements with less parallax error
A pupilometer measures pupillary distance more accurately than a PD ruler by directly viewing the pupils through an optical system, reducing parallax error, and providing monocular measurements.
The Geneva lens gauge (lens clock) measures:
Answer: The surface power (base curve) of a lens surface
The Geneva lens gauge (lens clock) measures the surface curvature (surface power) of a lens, allowing calculation of the approximate power of each surface.
Which ANSI Z80.1 tolerance applies to the sphere power of a single vision lens with a prescribed power of -4.50 D?
Answer: ±0.13 D
Per ANSI Z80.1, for powers over ±3.375 D (up to ±6.375 D), the tolerance is ±0.13 D for sphere power.