Age-related macular degeneration and other macular diseases commonly lead to irreversible loss of the central visual field. In these cases of central field loss (CFL), patients must rely on peripheral vision to recognize objects, identify faces, and read. However, performance on these form vision tasks is far worse than the reduced spatial resolution in peripheral vision predicts. The causes of this excess impairment are not well understood. Further, we do not know to what extent changes can be induced in the peripheral visual system to alleviate these impairments over the long term, nor do we understand the nature of such plasticity. A basic understanding of peripheral form vision is necessary if we are to develop effective rehabilitation regimens and adaptive technologies for patients with central vision loss. An equally important advance would be to understand why form vision is qualitatively inferior in peripheral compared to central vision. The proposed study aims to make foundational advances in our understanding of peripheral form vision, and does so in a way that is relevant for the condition of CFL. We propose to study peripheral form vision from the perspective of active vision, where oculomotor control plays a central role. Specifically, we will focus on the interaction between plasticity in visual crowding, a key form vision deficit in the periphery, and changes in oculomotor strategy induced by CFL. We will begin by testing a novel theory that links crowding in normal peripheral vision to image statistics that have been acquired under the influence of saccadic eye movements. We will build an image-encoding model of early visual processing stages based on the theoretical framework we recently developed. This model of peripheral form vision will be validated quantitatively against a diverse set of findings on crowding in the literature. Separately, we will test a new theory of oculomotor development that describes the formation of the preferred retinal locus (PRL), which is a common adjustment in CFL. The image-encoding model will enable us to predict the nature of form vision plasticity given a PRL. This research project thus stands to provide the first comprehensive theory of peripheral form vision in the context of central field loss. In addition, it will produce a rich an unique data set on peripheral form vision and oculomotor adaptation that will inform other investigations of peripheral form vision.
Macular disorders, and in particular age-related macular degeneration, are a leading cause of low vision and blindness. Losing the macula (fovea) will force a person to use his/her peripheral vision to perform important form-vision tasks such as reading, face identification, and object recognition. However, peripheral vision is ill suited for these tasks, for reasons that are not well understood. Moreover, we lack data and models that describe and predict how peripheral vision adapts to the loss of the central visual field. The proposed research will fill this knowledge gap. The data and predictive models that will result from this study can inform the development of effective rehabilitation regimens and adaptive technologies for patients with central vision loss.
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