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Vanessa Doyon-Cadieux, Constantina Stamoulos, Aaron Johnson; Eye movements when viewing natural scenes with normal vision and simulated scotomas. Journal of Vision 2009;9(8):395. doi: 10.1167/9.8.395.
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Purpose: Age-related macular degeneration (AMD) results in central retinal defects due to photoreceptor degeneration (dry AMD) or photoreceptor distortion by abnormal blood vessel growth (wet AMD). Individuals with AMD must compensate by making use of the unaffected peripheral vision. Consequently, this might lead to alternative eye movement (EM) strategies when performing visual search tasks, resulting in an increase in EM frequency. Methods: We recorded binocular EM (Eyelink 1000 tracker) while observers performed two natural tasks: visual search and free-viewing. Using the recorded eye position, images at the current fixation were either distorted (wet AMD), removed (dry AMD) or left intact (control, no AMD). Results: Under the simulated AMD conditions, fixation frequency and duration increased, and saccades were of greater amplitude. Behavioural results show that it took longer to find the target with simulated AMD conditions in comparison to the control condition. Type of AMD also has an effect on the EMs, with fixation duration being longer, and saccade amplitudes being smaller for wet AMD in comparison to dry AMD. In the free-viewing experiment, similar results were obtained. Conclusions: These results imply that while visual tasks can still be performed with central vision loss, they lead to impaired visual performance. In addition, different EM strategies between wet and dry AMD lead us to the conclusion that visual aids and training programs designed to incorporate remaining peripheral vision must take into consideration the cause of the scotoma.
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