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H. Nakamura, S. Kashii, T. Nagamine, Y. Matsui, Y. Honda, H. Shibasaki; Visual Motion Perception in Human V5 of Glaucoma Patients Demonstrated by Magnetoencephalography . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4104.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the visual motion perception in early glaucoma. Methods: Three glaucoma patients (visual field deficit within a quarter quadrant) and eight healthy volunteers participated in this study. Random dot kinematograms composed of 320 white dots were projected on a global dark background. Each dots moved smoothly with a constant speed. Coherent movement of 390 ms and random movement of 1320 ms were presented alternately. During the coherent motion, total dots moved in a uniform one of four directions; (right, left, up, down). Visual stimulations were given to the full-field (experiment 1) and to left hemi-field, left upper or lower quadrant of each subject (experiment 2). Experiment 1 was performed to all subjects, and experiment 2 to healthy volunteers. The subjects looked at the fixation point with their left eyes. The magnetic responses were recorded by a whole head magnetometer, and averaged with respect to the onset of coherent motion. Results: We concentrated only on the first component in the right hemisphere. In experiment 1, mean peak latencies (±S.D.) were 271±6.5 ms for glaucoma patients and 219±25.1 ms for healthy subjects. In experiment 2, the peak latency in the left upper quadrant field stimulation was significantly delayed for both full-field and left hemi-field. The mean latencies (±S.D.) for left hemi-field, left upper and lower quadrant field stimulation were 229±24.7, 265±51.7 and 239±27.8 ms, respectively. Estimated sources of all subjects were consistently identified within human V5. As the masking area was enlarged, the dipole strength (±S.D.) correspondingly decreased from 10±6.1, 6±3.5, to 5±3.2 and 5±3.3 nAm in full-field, left hemi-field, left upper and lower quadrant field, respectively. 6±4.1 nAm was for glaucoma patient. Conclusions: Visual deficit doesn’t influence the peak latency on normal human motion perception until it covers visual field of three-fourth. In the early stage of glaucoma, the peak latency and dipole strength were delayed and reduced in full field visual stimulation.
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