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Christina Moutsiana, Radwa Soliman, Lee de-Wit, Martin I. Sereno, Gordon Plant, D. Samuel Schwarzkopf; Case study of unexplained visual field loss and perceptual deficits in the presence of normal early visual function . Journal of Vision 2014;14(10):48. doi: 10.1167/14.10.48.
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© ARVO (1962-2015); The Authors (2016-present)
Previous work on patients with visual cortex lesions has shown that some visual function can be preserved in the absence of conscious perception. Here we present a patient (female, 50yrs) with monocular vision since 8 years old because of tumor in the other eye. She shows unexplained visual field loss and deficits in visual perception in the absence of any evidence of structural damage to the early visual pathway or lesions in visual cortex. Perimetry demonstrated severe anopia of the lower visual field and a clockwise progression of the loss through the upper left visual field over several years. Behavioral and functional magnetic resonance imaging data were collected during two visits, one year apart. The patient and three healthy controls viewed moving wedge and ring stimuli for retinotopic mapping while images were acquired in a Siemens Avanto 1.5T MRI scanner. We performed population receptive field (pRF) analysis to map the functional organization of visual cortex. Despite the visual field loss, the patient's retinotopic maps and pRF parameters in occipital cortex were qualitatively normal. Control analyses confirmed that this was not an artefact of pRF analysis methods. Additional behavioral data confirmed the perimetry results using identical stimuli as used for retinotopic mapping: the patient could only detect stimuli presented in the upper right visual quadrant. The patient did not show evidence of blindsight. Furthermore a severe deficit in perceptual grouping and integration was revealed using the Leuven Perceptual Organisation Screening Test (L-POST) while simple visual ability was relatively preserved. Taken together, our findings suggest that apparently normal functional organization of visual cortex does not guarantee conscious perception across the visual field.
Meeting abstract presented at VSS 2014
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