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Preeti Verghese, Christian P Janssen; Scotoma Awareness and Eye Movement Training in Age-Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2620.
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© ARVO (1962-2015); The Authors (2016-present)
As most individuals with age related macular degeneration are unaware of their scotoma, we seek to: 1. Develop a paradigm to increase scotoma awareness and 2. Train the preferred retinal locus (PRL) to move towards the scotoma to reveal information obscured by the scotoma.
We first estimated the extent of monocular scotoma and the loci of fixation using a scanning laser ophthalmoscope. We also estimated the location of the binocular scotoma using a custom program that projected stimuli on a large screen. Our goal was to train individuals to direct their PRL toward the scotoma, to uncover missing information. The training paradigm involved comparing two stimuli located on opposite sides of the PRL to determine if they were the same or different. One stimulus was hidden behind the individual’s binocular scotoma and the other was clearly visible in the location opposite the scotoma. As the task required knowing the identity of both stimuli, moving the PRL towards the scotoma was the best way to reveal the obscured stimulus. Observers were trained in multiple blocks over two practice sessions.
At the start of training, patients initially looked at the visible stimulus (away from the scotoma), but with practice they began to direct their PRL toward the scotoma. The attached figure shows how well participants were able to direct their saccades towards the target, after training and at a 2-month follow-up viist. At the end of training, 4 out of 7 individuals made saccades more than half way toward the hidden target. At the 2-month retention assessment, all observers consistently made saccades toward the the target hidden in the scotoma. Self-reports suggest increased subjective awareness of scotoma location for some, which could explain the high proportion of saccades towards the scotoma.
A visual search task designed to direct eye movements toward the scotoma improves both scotoma awareness and eye movement efficiency.
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