Ocular torsion: rotations around the “WHY” axis

Kushner, Burton J.

doi:10.1016/j.jaapos.2003.09.004

Cited by 50 publications

(65 citation statements)

References 32 publications

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“…The 3-step test's mechanism is generally misunderstood. Kushner [92] has pointed out that were traditional teaching true, then IO weakening, the most common surgery for SO palsy, should increase the head tilt-dependent change in hypertropia; the opposite is observed. Among numerous inconsistencies with common clinical observations [92], bilateral SO palsy should cause greater head tilt-dependent change in hypertropia than unilateral SO palsy; however, the opposite is found [93].…”

Section: Implications For Strabismusmentioning

confidence: 99%

“…Kushner [92] has pointed out that were traditional teaching true, then IO weakening, the most common surgery for SO palsy, should increase the head tilt-dependent change in hypertropia; the opposite is observed. Among numerous inconsistencies with common clinical observations [92], bilateral SO palsy should cause greater head tilt-dependent change in hypertropia than unilateral SO palsy; however, the opposite is found [93]. Modeling and simulation of putative effects of head tilt in SO palsy suggest that SO weakness alone cannot account for typical 3-step test findings [94,95].…”

Section: Implications For Strabismusmentioning

confidence: 99%

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Mechanics of the Orbita

Demer

2007

Developments in Ophthalmology

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The oculomotor periphery was formerly regarded as a simple mechanism executing complex behaviors explicitly specified by innervation. It is now recognized that several fundamental aspects of ocular motility are properties of the extraocular muscles (EOMs) and their associated connective tissue pulleys. The Active Pulley Hypothesis proposes that rectus and inferior oblique EOMs have connective tissue soft pulleys that are actively controlled by the action of the EOMs' orbital layers. Functional imaging and histology have suggested that the rectus pulley array constitutes an inner mechanism, similar to a gimbal, that is rotated torsionally around the orbital axis by an outer mechanism driven by the oblique EOMs. This arrangement may mechanically account for several commutative aspects of ocular motor control, including Listing's law, yet permits implementation of noncommutative motility as during the vestibulo-ocular reflex. Recent human behavioral studies, as well neurophysiology in monkeys, are consistent with mechanical rather than central neural implementation of Listing's law. Pathology of the pulley system is associated with predictable patterns of strabismus that are surgically treatable when the pathologic anatomy is characterized by imaging. This mechanical determination may imply limited possibilities for neural adaptation to some ocular motor pathologies, but indicates greater potential for surgical treatments.

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Section: Implications For Strabismusmentioning

confidence: 99%

Section: Implications For Strabismusmentioning

confidence: 99%

Mechanics of the Orbita

Demer

2007

Developments in Ophthalmology

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“…Measuring this rotation is challenging [17,19] and, just as in the development of theories for deformable elastic rods (cf. [1,10,23]), the term "torsion" can be confusing.…”

Section: Listing's Law Implies Donders' Lawmentioning

confidence: 99%

“…The velocity plane V(t) associated with R(t) has a normal vector w 3 (t) defined by (19). As β = 0, we can compute p · w 3 (t):…”

Section: Listing's Half-angle Rulementioning

confidence: 99%

On geodesics of the rotation group SO(3)

Novelia

O’Reilly

2015

Regul. Chaot. Dyn.

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The simplest model with which to examine the dynamics of the human eye consists of a rigid body which is free to rotate about a fixed point. Two classical laws governing monocular vision, which are known as Listing's law and Donders' law, can be enforced in this model using a single holonomic constraint. While there has been considerable attention paid to the kinematics of the eye, the dynamics of the eye predicted by rigid body models has not received the same level of attention. In the present paper, the unforced dynamics of the resulting rigid body model are examined with particular emphasis placed on the geodesics of the configuration manifold. A comprehensive portrait of these motions is presented, and the insight gained is related to the dynamics of the gaze direction and saccadic motions of the eye. Among our results, we find that modeling the eye as an asymmetric rigid body produces a nonintegrable system of governing equations and that the geodesics on the configuration manifold provide a wealth of potential motions for the gaze direction.

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“…For instance, the measure of ocular torsion can provide relevant clinical information to detect central (neurological) or peripheral (ophthalmological or otological) disorders (Kushner, 2004). As importantly, from a theoretical point of view, it is still unclear if the ocular torsion signal is taken into account by the central nervous system.…”

mentioning

confidence: 99%