General Practice 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 General Practice flashcards as text
Compared to CR-39 (index 1.50), a lens with a refractive index of 1.67 will be:
Answer: Thinner and lighter for the same prescription
Higher refractive index materials bend light more efficiently, allowing lenses to be made thinner for the same prescription power.
The distance from the back surface of the spectacle lens to the front of the cornea is called the:
Answer: Vertex distance
Vertex distance is clinically important for high prescriptions (typically ±4.00 D and above) because changes affect effective power.
Which multifocal lens type has no visible dividing line between distance and near zones?
Answer: Progressive addition lens
Progressive addition lenses provide a gradual power transition without a visible segment line.
A patient is prescribed base-in prism. The perceived image will be displaced toward:
Answer: The apex (temporally)
Light bends toward the base of a prism, but the perceived image is always displaced toward the apex.
Anti-reflective coatings reduce reflections using the principle of:
Answer: Destructive interference
AR coatings use thin film layers whose reflected waves are out of phase and cancel each other through destructive interference.
Which measurement ensures the optical center of a lens aligns vertically with the patient's pupil?
Answer: Optical center height (fitting height)
Optical center height (fitting height) is measured from the lowest point of the frame to the pupil center while the patient looks straight ahead.
Polycarbonate lenses are recommended for safety eyewear primarily because of their:
Answer: Superior impact resistance
Polycarbonate has very high impact resistance, making it the preferred material for safety and children's eyewear.