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Susana Chung, Mehmet Agaoglu, Girish Kumar; Do eye movements referenced to an extra-foveal retinal location in the absence of a functioning fovea?. Journal of Vision 2016;16(12):1336. doi: 10.1167/16.12.1336.
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© ARVO (1962-2015); The Authors (2016-present)
People with bilateral macular disease usually adopt a retinal location near the edge of their retinal lesioned area for seeing — the preferred retinal locus (PRL). Is the PRL the new reference locus for oculomotor movements in response to the loss of a functioning fovea? Here, we examined whether microsaccades made during fixation, or saccades made voluntarily in response to a moving target, bring an object of interest toward the fovea (absence of oculomotor re-referencing) or the PRL (evidence of oculomotor re-referencing). Images of the retina showing the target retinal locations were recorded using a high-resolution scanning laser ophthalmoscope while participants with long-standing bilateral macular disease either fixated at a target, or made saccades to follow a target that jumped between different positions. Eye positions were extracted from the recordings using a brute-force cross-correlation algorithm at a sampling rate of 540 Hz. Retinal locations corresponding to the target location before and after each saccade were determined. The vector error of the landing position of each saccade was calculated with respect to the fovea and the PRL. For fixation trials, vector errors of microsaccades were much smaller when calculated with respect to the PRL than the fovea, suggesting that microsaccades during fixation were directed toward the PRL, not the fovea, evidence of oculomotor re-referencing. In contrast, vector errors of saccades made during voluntary saccade trials were not different when analyzed with respect to the fovea or the PRL, implying no clear single reference location for voluntary saccadic eye movements. Our findings of the different extent to which saccades were directed toward the PRL for fixation vs. voluntary-saccade tasks suggest that the neural circuits or control of different types of eye movements are associated with different degrees of plasticity, elucidating important properties of the neural control of eye movements in general.
Meeting abstract presented at VSS 2016
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