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Refraction and Retinoscopy 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.

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  1. Which test is used during subjective refraction to balance accommodation between the two eyes after binocular balancing?

    Answer: Prism dissociation test

    The prism dissociation test uses vertical prisms to dissociate the two eyes so that each eye's accommodation can be balanced independently.

  2. A Jackson cross cylinder (JCC) is used to refine which two components of a refraction?

    Answer: Cylinder power and cylinder axis

    The JCC is a ±0.25 or ±0.50 D cross cylinder used to refine both the axis and power of the correcting cylinder.

  3. During static retinoscopy, the examiner uses a streak retinoscope. Rotating the streak reveals the principal meridians of astigmatism when the streak is:

    Answer: Aligned parallel to the axis of the reflex to show the fastest or brightest reflex

    In streak retinoscopy, aligning the streak with a principal meridian shows the reflex in that meridian most clearly for neutralization.

  4. A patient's best-corrected visual acuity is 20/30 with −4.00 +2.00 ×090. If you add −0.50 D of sphere and acuity drops to 20/40, what does this indicate?

    Answer: The endpoint was correct; additional minus over-minuses the patient

    A drop in acuity with additional minus confirms the previous endpoint was correct and more minus causes over-correction.

  5. What is vertex distance and why is it clinically important?

    Answer: Distance from corneal apex to lens back surface; affects effective power for high corrections

    Vertex distance is the distance from the corneal apex to the spectacle lens back surface and significantly affects the effective power for prescriptions above ±4.00 D.

  6. The duochrome (bichrome) test uses red and green targets to refine sphere. The endpoint is when:

    Answer: Letters on both red and green backgrounds appear equally clear

    At the correct endpoint, chromatic aberration places the circle of least confusion on the retina so red and green appear equally sharp.

  7. Which type of astigmatism has both focal lines in front of the retina?

    Answer: Compound myopic astigmatism

    Compound myopic astigmatism has both principal meridians myopic, placing both focal lines anterior to the retina.