“Starkfest” Vision and Clinic Science Special Issue

Zangemeister, Wolfgang H.; Oechsner, Ulrich; Freksa, Christian

doi:10.1097/00006324-199507000-00006

Cited by 44 publications

(3 citation statements)

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“…A future study with a hemianopic control group undergoing testing in four sessions but no training would be required to rule out the role of spontaneous recovery. Spontaneous oculomotor adaptation in patients with homonymous hemianopia is very well documented [25, 27, 33, 57] although hemianopic patients with additional damage to occipito-parietal cortex or posterior thalamus appear less likely to spontaneously adopt compensatory oculomotor strategies [24]. An earlier small cross-sectional study of hemanopic patients suggests a relatively long time-course for spontaneous recovery which takes 6 months to develop and may continue to evolve for over a year [26].…”

Section: Discussionmentioning

confidence: 99%

“…In some cases, HH disrupts normal scanning patterns with patients exhibiting disorganised scanpaths with high rates of refixation and inaccurate saccades [24] and it has been proposed that the loss of re-entrant pathways from higher visual areas to the damaged striate cortex may result in uncertainty about spatial locations across saccades [3]. Some patients make a series of small saccades, with long latencies into their blind field [25–27]. In light of these scanpath abnormalities, patients are often trained to make systematic horizontal or vertical scanning saccades into their blind field (oculomotor training) [5, 24, 27–29].…”

Section: Introductionmentioning

confidence: 99%

“…Some patients make a series of small saccades, with long latencies into their blind field [25–27]. In light of these scanpath abnormalities, patients are often trained to make systematic horizontal or vertical scanning saccades into their blind field (oculomotor training) [5, 24, 27–29]. Training usually leads to an enlargement of the region in which subjects can successfully locate a target with eye movements (the visual search field, VSF) and a reduction in response times [5, 29–31].…”

Section: Introductionmentioning

confidence: 99%

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Compensatory strategies following visual search training in patients with homonymous hemianopia: an eye movement study

2010

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A total of 29 patients with homonymous visual field defects without neglect practised visual search in 20 daily sessions, over a period of 4 weeks. Patients searched for a single randomly positioned target amongst distractors displayed for 3 s. After training patients demonstrated significantly shorter reaction times for search stimuli (Pambakian et al. in J Neurol Neurosurg Psychiatry 75:1443–1448, 2004). In this study, patients achieved improved search efficiency after training by altering their oculomotor behaviour in the following ways: (1) patients directed a higher proportion of fixations into the hemispace containing the target, (2) patients were quicker to saccade into the hemifield containing the target if the initial saccade had been made into the opposite hemifield, (3) patients made fewer transitions from one hemifield to another before locating the target, (4) patients made a larger initial saccade, although the direction of the initial saccade did not change as a result of training, (5) patients acquired a larger visual lobe in their blind hemifield after training. Patients also required fewer saccades to locate the target after training reflecting improved search efficiency. All these changes were confined to the training period and maintained at follow-up. Taken together these results suggest that visual training facilitates the development of specific compensatory eye movement strategies in patients with homonymous visual field defects.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Compensatory strategies following visual search training in patients with homonymous hemianopia: an eye movement study

2010

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Adaptation to Visual Field Defects with Virtual Reality Scotoma in Healthy Subjects

Zangemeister¹,

Oechsner²

1999

Current Oculomotor Research

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Saccades to the seeing visual hemifield in hemidecorticate patients exhibit task-dependent reaction times and hypometria

Herter

Guitton

2007

Exp Brain Res

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In three patients who had one cortical hemisphere removed surgically (hemidecortication), we studied visually-triggered saccades directed contralateral to the intact cortical hemisphere (i.e., ipsilesional saccades). Both saccade reaction times (SRTs) and accuracy of these saccades have been reported as abnormal in hemidecorticate patients, but not monkeys. One explanation for this difference is that deficits in hemidecorticate patients may not have been directly caused by removal of cortical oculomotor structures themselves, but may have been a manifestation of compensatory strategies used to cope with contralesional hemianopia. We hypothesized that deficits in saccade performance to the ipsilesional (seeing) visual hemifield would be directly linked to how easily patients could localize targets in their blind hemifield with searching saccades. To test this hypothesis, we examined how deficits in our patients varied when targets were: (1) randomly presented to either the seeing or blind hemifield for long durations thereby permitting searching saccades in the blind hemifield; (2) presented as in Experiment 1, but briefly flashed thereby removing visual feedback prior to saccade onset thereby rendering searching saccades useless; (3) briefly flashed as in Experiment 2, but at random locations in only the seeing hemifield (blind hemifield irrelevant). Mean SRTs to the seeing hemifield were 165 ms longer than normal in Experiment 2, but only about 40 ms longer in Experiments 1 and 3. Saccade accuracy was characterized by task-dependent hypometria in all three experiments with a mean undershoot of about twice the amplitude variance. The largest undershoots were in Experiments 2 and 3. Our data suggest that deficits resulted from the direct effects of the lesions themselves coupled with context-dependent strategies used to cope with contralesional hemianopia.

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“Starkfest” Vision and Clinic Science Special Issue

Cited by 44 publications

References 0 publications

Compensatory strategies following visual search training in patients with homonymous hemianopia: an eye movement study

Compensatory strategies following visual search training in patients with homonymous hemianopia: an eye movement study

Adaptation to Visual Field Defects with Virtual Reality Scotoma in Healthy Subjects

Saccades to the seeing visual hemifield in hemidecorticate patients exhibit task-dependent reaction times and hypometria

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