CO Ocular Motility Evaluation & Binocular Vision Assessment 3

Question 1

The Bielschowsky head tilt test is positive (hypertropia increases on ipsilateral head tilt) with palsy of which muscle?

Accepted Answer

Ipsilateral superior oblique

Answer

On ipsilateral head tilt, the ipsilateral superior oblique and superior rectus are stimulated; if the superior oblique is paretic, the superior rectus acts unopposed causing hypertropia.

Question 2

Which finding on prism alternate cover test (PACT) suggests a restrictive etiology rather than a paretic one?

Accepted Answer

Forced duction test positive

Answer

A positive forced duction test (resistance to passive eye movement) confirms mechanical restriction rather than muscle paresis.

Question 3

Stereopsis of 40 seconds of arc corresponds to which clinical level?

Accepted Answer

Fine (central) stereopsis consistent with normal binocular vision

Answer

40 arcsec is near-normal fine stereoacuity, consistent with intact bifoveal binocular vision.

Question 4

In Duane retraction syndrome type I, which finding is characteristic on attempted adduction?

Accepted Answer

Globe retraction and narrowing of the palpebral fissure

Answer

Type I Duane syndrome shows limited abduction and, on adduction, globe retraction with palpebral fissure narrowing due to co-contraction of horizontal recti.

Question 5

Which motility finding is pathognomonic for internuclear ophthalmoplegia (INO)?

Accepted Answer

Ipsilateral adduction deficit with contralateral abducting nystagmus

Answer

INO results from a medial longitudinal fasciculus lesion causing ipsilateral adduction failure and dissociated nystagmus in the contralateral abducting eye.

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CO Ocular Motility Evaluation & Binocular Vision Assessment 3