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Ophthalmic Dispensing Flashcards

7 cards from real ABO 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 Dispensing flashcards as text

  1. A patient requires 2Δ base-down prism OD and 2Δ base-up prism OS. This is an example of:

    Answer: Compensating prism

    Compensating prism uses opposite bases in each eye to correct a vertical phoria, as opposed to yoked prism where both eyes receive the same base direction.

  2. Slab-off (bicentric grinding) is most commonly used to correct:

    Answer: Vertical imbalance at the near zone in high anisometropic prescriptions

    Slab-off creates a prism difference at the near zone to compensate for the vertical prismatic imbalance caused by anisometropia when reading through bifocals.

  3. The vertex distance significantly affects the effective power of lenses with power greater than approximately:

    Answer: ±5.00 D

    Vertex distance compensation becomes clinically significant for powers of ±5.00 D or higher, where small changes in distance materially change the effective power at the eye.

  4. Which lens treatment absorbs UV radiation below 400 nm and is built into the lens material rather than applied as a coating?

    Answer: UV inhibitor (UV absorber)

    A UV inhibitor is incorporated into the lens monomer during manufacturing, providing UV400 protection as an inherent lens property, not a surface treatment.

  5. When dispensing a frame to a patient with a high nose, which bridge adjustment is most appropriate?

    Answer: Increase the splay angle of the nose pads

    Increasing the splay (flare) angle of the nose pads spreads them wider to accommodate a higher nose bridge and raise the frame on the face.

  6. A Fresnel prism is most accurately described as:

    Answer: A thin, lightweight press-on prism made of concentric prismatic rings

    A Fresnel prism is a thin plastic press-on membrane with concentric prismatic grooves that approximates the effect of a full glass prism with minimal weight and thickness.

  7. The American National Standards Institute (ANSI Z80.1) tolerance for cylinder axis on a prescription of -1.50 D cylinder is:

    Answer: ±5°

    ANSI Z80.1 specifies a cylinder axis tolerance of ±5° for cylinder powers between 0.25 D and 2.00 D.