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Binocular Vision & Strabismus 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.

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  1. The AC/A ratio expresses the relationship between:

    Answer: The amplitude of accommodation and the degree of convergence per diopter of accommodation

    The AC/A (accommodative convergence/accommodation) ratio quantifies how many prism diopters of convergence are elicited per diopter of accommodation exerted.

  2. Microtropia (monofixation syndrome) is best characterized by:

    Answer: A small-angle tropia with peripheral binocular fusion and central suppression scotoma

    Monofixation syndrome (microtropia) features a small angle strabismus with a central suppression scotoma in the deviating eye but preserved peripheral fusion, giving reduced but measurable stereopsis.

  3. A hypertropia is defined as a vertical deviation in which the deviating eye turns:

    Answer: Upward

    Hypertropia describes an upward vertical deviation of the eye; the prefix 'hyper-' means above or higher.

  4. The Bielschowsky head tilt test is a critical diagnostic maneuver for identifying palsy of which cranial nerve?

    Answer: Cranial nerve IV (trochlear)

    In trochlear (CN IV) palsy, tilting the head to the affected side increases the hyperdeviation because the superior rectus (an intorter) acts as an elevator when the superior oblique is paretic.

  5. The primary purpose of a suppression scotoma in a patient with constant strabismus is to:

    Answer: Eliminate diplopia by inhibiting the image from the deviating eye's fovea

    Cortical suppression of the fovea of the deviating eye is an adaptive response to prevent diplopia (and visual confusion) caused by the misaligned eye.

  6. Measuring the near point of convergence (NPC) is performed primarily to evaluate:

    Answer: The maximum convergence ability of the eyes

    The NPC test determines the closest point at which a patient can maintain single binocular vision by converging, directly reflecting maximum convergence amplitude.

  7. A patient whose exophoria is significantly greater at distance than at near most likely has which binocular vision condition?

    Answer: Divergence excess (or simulated divergence excess)

    When an exodeviation is substantially larger at distance than at near, the clinical classification is divergence excess, reflecting an inability to maintain adequate fusional divergence at far.