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Optometry Flashcards

7 cards from real COT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Optometry flashcards as text

  1. A patient wearing +2.50 D lenses moves a held object away and the image appears to move in the same direction. This is called:

    Answer: With motion

    Plus lenses act as converging lenses and produce 'with' apparent motion when the object is beyond the focal point.

  2. What does the vertex distance affect most significantly in high-powered prescriptions?

    Answer: Effective power of the lens

    Vertex distance changes the effective power of a lens; this effect is clinically significant for prescriptions exceeding ±4.00 D.

  3. Which refractive surgery procedure reshapes the cornea using a microkeratome or laser to create a flap before ablation?

    Answer: LASIK

    LASIK (Laser-Assisted In Situ Keratomileusis) involves creating a corneal flap before excimer laser ablation of the stromal bed.

  4. A patient with 20/200 best-corrected visual acuity in the better eye meets the definition of legal blindness in the US. What is the other criterion for legal blindness?

    Answer: Visual field less than 20 degrees

    Legal blindness is defined as best-corrected VA of 20/200 or worse, OR a visual field of 20 degrees or less in the better eye.

  5. Induced prism from decentered lenses can be calculated using Prentice's Rule. What is the induced prism for a -4.00 D lens decentered 5 mm?

    Answer: 2.0 prism diopters

    Prentice's Rule: prism (Δ) = diopters × decentration (cm) = 4.00 × 0.5 = 2.0 prism diopters.

  6. Which lens design provides the widest clear optical zone and is preferred for high-power prescriptions to minimize aberrations?

    Answer: Aspheric lens

    Aspheric lens designs reduce peripheral aberrations and distortion, making them particularly beneficial for high-powered prescriptions.

  7. When converting a minus cylinder prescription to plus cylinder form, -2.00 -1.00 x 045 becomes:

    Answer: -3.00 +1.00 x 135

    To transpose: new sphere = algebraic sum (-2.00 + -1.00 = -3.00), new cylinder = same magnitude opposite sign (+1.00), new axis = 90° from old axis (045+90=135).