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VISUAL SCANNING IN PATIENTS WITH UNILATERAL VISUAL NEGLECT DUE TO RIGHT-SIDED CEREBRO-VASCULAR LESION Noriko Kamakura 1 1Tokyo Metropolitan Institute of Gerontology pp.1119-1125
Published Date 1984/11/1
DOI https://doi.org/10.11477/mf.1406205414
  • Abstract
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The characteristics of visual scanning in patients with unilateral visual neglect (UVN) were studied. Forty-one patients who showed UVN in the figure finding test and 21 patients who showed no UVN in the test were selected from 176 patients with the right-sided cerebro-vascular lesion. They ranged in age from 46 to 78 years. The severity of UVN in each subject was determined by the number of the figures neglected unilaterally in the figure finding test in which a subject was asked to circle the designated figures scattered among the other figures on the test paper. The following two tests were administered to each subject. Test 1 examined binocular peripheral vision by tachistoscopic method in which a white circle of 1°was presented for 1/8 sec at 15° from the central fixation point either unilaterally or bilaterally. Test 2 investigated the movement of gazing point while a subject was searching a target on a screen with his or her head stabilized. It was recorded on 16 mm movie Elm with Eye-Mark Recorder Model IV (Nac Co.) and converted into a series of position coordinates from which a visual scan path was reproduced and values cf variables representing characteristics of visual scanning were computed.

Six of 19 subjects who demonstrated "mild" UVN were found their peripheral vision intact. The characteristics of their visual scan path didnot differ from the ones of the other 9 subjects who demonstrated "no" UVN as well as intact peripheral vision. The visual scan paths of the subjects with UVN as well as defective left pe-ripheral vision were significantly different from the ones of those with the intact peripheral vision and no UVN. Two major characteristics were found in those patients. First, the relative frequen-cies of saccades were low both in left and in right direction. These frequencies are also low in upward and downward direction to the less extent in right and left direction. Secondly, the distance from the initial fixation point to the left limit of the search was short. These two characteristics were found in the greatest degree in thcse with "severe" UVN, whose scanning advanced by piecemeal within almost the right-side half of their initial visic n. The patients with the "mild" UVN demonstrated those characteristics in the less degree. The patients with the defective pe-ripheral vision and "no" UVN did net differ from the patients with the intact peripheral vision and "no" UVN in the distance frcm the initial fixa-tion point to the left limit of the search, but dif-fered in the relative frequencies of saccades.

The findings seem to indicate that; 1) the func-tional defect in left peripheral vision may affect the quality of UVN, and 2) the level of mental activity may determine the severity of UVN among those with defective left peripheral vision.


Copyright © 1984, Igaku-Shoin Ltd. All rights reserved.

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電子版ISSN 2185-405X 印刷版ISSN 0006-8969 医学書院

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