Abstract
Gaze control is required for applying visual stimuli to a particular area of the visual field. We developed a visual field test with gaze check tasks to investigate hemianopia. In this test, participants must report the presence or absence of visual stimuli when a small object at the fixation point vibrates. Trials in the absence of visual stimuli were used as gaze check tasks, since the vibration could be observed only when the gaze was directed at the fixation point. We evaluated the efficacy of our test in four control participants and one patient with homonymous hemianopia who was unaware of the defects in the left visual field. This patient presented hemianopia in the test with gaze check tasks, but not when the gaze check tasks were omitted. The patient showed spontaneous gaze movements from the fixation point to the upper left direction, as well as scanning of the left visual field during the test without gaze check tasks. Thus, we concluded that the visual defects in this patient were compensated in daily life by spontaneous eye movements coordinated with visual information processing. The present results show the usefulness of the visual field test with gaze check tasks.
Highlights
Visual information is received by the cerebral cortex via the lateral geniculate body and primary visual cortex, and this pathway enables us to see the external world [1, 2]
To estimate the extent of gaze control during the visual field test, we measured the probability of detecting the star vibration that was placed away from the fixation point in four control participants
The visual field test in this study was developed for the latter purpose, and various visual stimuli can be applied to the left or right visual field (Supplementary Video 1)
Summary
Visual information is received by the cerebral cortex via the lateral geniculate body and primary visual cortex, and this pathway enables us to see the external world [1, 2]. Cortical visual impairment after cerebral infarction ameliorates spontaneously in patients who undergo quantitative perimetry as part of their routine care [6]. To test a specific part of the visual field, the patient has to look at the fixation point. We combined visual field tests with gaze check tasks that can be answered only when the patient looks at a small object at the fixation point. If the performance in the gaze check tasks was insufficient, the visual field test results were discarded. Such conditions work as a pressure for the patient to concentrate on gaze control, and the results are discarded only when the patient is exhausted
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