Pursuit Is Impaired but the Vestibulo-ocular Reflex Is Normal in Infantile Strabismus

Tychsen, Lawrence; Hurtig, Richard R.; Scott, William E.

doi:10.1001/archopht.1985.01050040078022

Cited by 81 publications

(42 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It would be worthwhile to test more exotropic subjects, looking for a naso-temporal asymmetry in pursuit. It is possible that this abnormality occurs in exotropia more frequently than has been appreciated (Tychsen et al 1985).…”

Section: Discussionmentioning

confidence: 46%

Ocular Motor Behavior in Macaques With Surgical Exotropia

Economides

Adams²,

Jocson³

et al. 2007

Journal of Neurophysiology

View full text Add to dashboard Cite

Economides JR, Adams DL, Jocson CM, Horton JC. Ocular motor behavior in macaques with surgical exotropia. J Neurophysiol 98: 3411-3422, 2007. First published October 10, 2007 doi:10.1152/jn.00839.2007. To provide an animal model of human exotropia, a free tenotomy of the medial recti was performed in two infant macaques. When the animals were old enough to record eye movements with video eye trackers, we measured their ductions, ocular alignment, comitance, smooth pursuit, fixation preference, and gaze stability. Partial recovery of adduction occurred in each monkey from spontaneous re-attachment of the medial rectus muscle to the eye. However, each animal was left with a relatively comitant, large angle exotropia. The magnitude of the exotropia was not affected by covering one eye. There was no dissociated vertical deviation or any significant "A" or "V" pattern to the horizontal misalignment. Smooth pursuit was more accurate when tracking nasally compared with temporally in both animals. Compensatory catch-up saccades in the tracking eye were always accompanied by conjugate movements in the deviated eye. Despite tenotomy of the medial recti, the velocity of adducting saccades was normal. Both monkeys alternated fixation, preferring to use the left eye for targets on the left side and the right eye for targets on the right. Each animal was capable of switching fixation while making accurate saccades. One of the monkeys developed a vertical pendular nystagmus, which was most prominent in the deviated eye. Macaques with ocular misalignment from medial rectus tenotomy exhibit features that are present in humans with alternating exotropia. These animals will be valuable for probing the cortical mechanisms that underlie visual suppression in strabismus.

show abstract

Section: Discussionmentioning

confidence: 46%

Ocular Motor Behavior in Macaques With Surgical Exotropia

Economides

Adams²,

Jocson³

et al. 2007

Journal of Neurophysiology

View full text Add to dashboard Cite

show abstract

“…Humans and monkeys with early-onset strabismus have a striking nasotemporal asymmetry of pursuit favouring nasalward motion during monocular viewing. 12,14,17,[70][71][72] Wong Page 2…”

Section: Smooth Pursuitsupporting

confidence: 41%

“…Humans and monkeys with early-onset strabismus have a striking nasotemporal asymmetry of pursuit favouring nasalward motion during monocular viewing. 12,14,17,[70][71][72] The asymmetry is exhibited transiently in normal human and monkey infants before the onset of binocularity, 58,59 but it persists permanently if strabismus develops in the neonatal period. 12,70 It is not seen in strabismus that develops after infancy.…”

Section: Smooth Pursuitmentioning

confidence: 42%

“…12,70 It is not seen in strabismus that develops after infancy. 17,73 When patients were asked to judge the speed of moving targets, they systematically underestimated the speed of a temporalward-moving target and overestimated that of a nasalward-moving target, even though the targets moved at identical speed. 12,74 Taken together, these observations suggest a link between aberrant binocularity and abnormal visual motion processing that affects pursuit pathways during the critical period for ocular motor development.…”

Section: Smooth Pursuitmentioning

confidence: 42%

See 1 more Smart Citation

Timing of surgery for infantile esotropia: sensory and motor outcomes

Wong

2008

Canadian Journal of Ophthalmology

View full text Add to dashboard Cite

Infantile esotropia is a common ophthalmic disorder in childhood. It is often accompanied by profound maldevelopment of stereopsis, motion processing, and eye movements, despite successful surgical realignment of the eyes. The proper timing of surgery has been debated for decades. There is growing evidence from clinical and animal studies that surgery during the early critical periods enhances sensory and ocular motor development. The Congenital Esotropia Observational Study has defined a clinical profile of infants who will benefit most from early surgery, and several other studies have shown that early surgery does not lead to adverse long-term effects. Clinicians now should consider offering early surgery to patients with large-angle, constant infantile esotropia at or before 10 months of age. Keywords stereopsis; eye movements; mVEP; motion perception; horizontal connections; primary visual cortex Infantile esotropia is a nasalward eye misalignment that begins in the first 6 months of life. It affects 1 in every 100 to 500 persons. 1,2 Infantile esotropia is characteristically large in magnitude (>20 prism diopters [PD]) and cosmetically conspicuous. While there is uniform agreement among pediatric ophthalmologists that a large-angle, constant infantile esotropia requires surgical correction, the proper timing of surgery has been debated for decades. 3,4 In North America, the typical age at surgery ranges from 11 to 18 months, and in many parts of Western Europe, surgery is delayed until 2 to 4 years of age. 5 Despite successful surgical realignment of the eyes, a number of sensory-motor deficits often persist into adulthood. 6,7 They include abnormal stereopsis, 8,9 latent fixation nystagmus, 10-12 dissociated vertical deviation, 12,13 abnormal eye movements (e.g., nasotemporal asymmetries of optokinetic nystagmus [OKN] [14][15][16] and smooth pursuit, 12,17 and abnormal ver-gence [18][19][20], as well as abnormal visual motion processing 7,21-23 and global motion perception. [24][25][26][27] In the last decade, advances in pediatric anesthesia and surgical techniques have made it possible to realign the eyes of strabismic infants at weeks or months of age. 28 CIHR Author ManuscriptCIHR Author Manuscript CIHR Author Manuscript critical periods the eyes are aligned, the more likely it is that normal binocular vision will develop. [30][31][32] Indeed, a number of clinical studies have shown that the sensory and ocular motor outcomes of children who had early surgery are substantially better than those who were repaired at the current standard age of surgery (referred to as surgery from 11 to 18 months of age in this review). This paper reviews the basic and clinical science literature on the critical periods of sensory and ocular motor development, then discusses the neural mechanisms that underlie the deficits typically seen in infantile esotropia. Following this, it examines current evidence in support of early surgery and discusses the clinical profile of infants who will most likely benefit fro...

show abstract

“…[10][11][12][13][14][15][16][17][18][19][20][21] Accordingly, the persistence of MNTA in infantile strabismus has been attributed to a cortical pursuit deficit caused by early failure of cortical binocular vision to develop. [22][23][24] Neonates show poor pursuit responses to focal moving stimuli but demonstrate strong optokinetic responses to large full-field rotating stimuli. [19][20][21] These full-field responses are attributed to the activation of subcortical optokinetic pathways that modulate full-field rotational optokinetic responses and remain active until maturation of binocular cortical pursuit pathways within the first 6 months of life.…”

mentioning

confidence: 44%