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Tonometry and Keratometry 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. Before performing Goldmann applanation tonometry, which topical agent combination is typically instilled?

    Answer: Fluorescein and a topical anesthetic

    Fluorescein stains the tear film to visualize the mires, and a topical anesthetic prevents reflex blinking and discomfort.

  2. In manual keratometry, irregular mire images (distorted or blurred rings) most commonly indicate:

    Answer: Corneal irregularity such as keratoconus or scarring

    Distorted or irregular mire reflections indicate an irregular corneal surface, which warrants further evaluation with corneal topography.

  3. What is the purpose of the biprism in a Goldmann applanation tonometer?

    Answer: To split the fluorescein image into two semicircles for endpoint detection

    The biprism splits the circular fluorescein ring into two semicircles that the examiner aligns to determine the applanation endpoint.

  4. Rebound tonometry (iCare) works on which principle?

    Answer: Induction and rebound of a small probe that contacts the cornea momentarily

    Rebound tonometry fires a small magnetized probe that briefly contacts the cornea; the deceleration and rebound speed are used to calculate IOP.

  5. When calibrating a Goldmann tonometer, the check weight is applied and the drum is set to 2 g. What result indicates the instrument is correctly calibrated?

    Answer: The balance arm swings freely to the up-stop

    Correct calibration at the 2 g check weight causes the balance arm to swing to the up-stop, confirming the spring tension is accurate.

  6. Which factor does NOT directly affect keratometry readings?

    Answer: Axial length of the eye

    Keratometry measures anterior corneal curvature; axial length is measured separately by A-scan biometry.

  7. A patient reports previous radial keratotomy (RK). Which tonometry method is LEAST affected by the altered corneal biomechanics after RK?

    Answer: Dynamic Contour Tonometry (DCT)

    Dynamic Contour Tonometry measures IOP by matching the contour of the cornea and is less influenced by corneal biomechanics than applanation methods.