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Ocular Motility and Alignment Flashcards

6 cards from real COA 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. During the cover-uncover test, the examiner covers the right eye. The left eye moves outward (temporally) to pick up fixation. This finding MOST likely indicates:

    Answer: Left esotropia

    If the uncovered (left) eye moves outward when the right eye is covered, the left eye was turned inward (esotropia) before coverage. The outward refixation movement reveals a manifest inward deviation of the left eye.

  2. In ocular motility testing using the H pattern (nine cardinal positions of gaze), which muscle is being evaluated when the patient looks to the right and UP?

    Answer: Right superior rectus (SR) and left inferior oblique (IO)

    In right and up gaze, the right superior rectus is the primary elevator and the left inferior oblique is the primary elevator of the fellow eye in that conjugate gaze position. The superior rectus and inferior oblique are yoke muscles (Hering's law) for upgaze.

  3. A patient reports diplopia that is WORSE when looking down and to the left. Which cranial nerve palsy is MOST likely?

    Answer: Right CN IV (trochlear) palsy

    The right superior oblique (CN IV) primarily depresses and intorts the eye. Diplopia that worsens in downgaze (especially when adducted, i.e., looking left with the right eye) is the classic presentation of a right CN IV palsy.

  4. The Hirschberg test estimates the angle of strabismus by observing corneal light reflections. If the corneal reflex appears at the pupil margin of the right eye and centered in the left eye, approximately how many prism diopters of deviation is estimated?

    Answer: 15–20 prism diopters

    In the Hirschberg test, a decentered corneal light reflex at the pupil margin corresponds to approximately 15 prism diopters (pd) of deviation. Each millimeter of decentration equals approximately 15 pd (some sources use 7° or 22 pd/mm depending on reference).

  5. Which test best evaluates for a latent deviation (phoria) that is only revealed when binocular fusion is disrupted?

    Answer: Alternate cover test

    The alternate cover test rapidly moves the occluder from eye to eye, preventing fusion and revealing both manifest (tropia) and latent (phoria) deviations. The cover-uncover test reveals only manifest deviations.

  6. A child is found to have a right esotropia measuring 30 prism diopters by the prism and alternate cover test. The child is 3 years old. What is the MOST important reason to treat this promptly?

    Answer: To prevent amblyopia from developing in the deviated eye

    In young children, strabismus causes the brain to suppress the input from the deviated eye to avoid diplopia. Prolonged suppression during the critical period of visual development leads to amblyopia (lazy eye) — a reduction in best corrected visual acuity that can become permanent if untreated.