Training eye movements for visual search in individuals with macular degeneration

Abstract

We report a method to train individuals with central field loss due to macular degeneration improve the efficiency of visual search. Our method requires participants to make a same/different judgment on two simple silhouettes. One silhouette is presented in an area that falls within the binocular scotoma while they are fixating the center of the screen with their preferred retinal locus (PRL); the other silhouette is presented diametrically opposite within intact visual field. Over the course of 480 trials (approximately 6 hours) we gradually reduce the amount of time that participants have to make a saccade and judge the similarity of stimuli. This requires that they direct their PRL first towards the stimulus that is initially hidden behind the scotoma. Results from 9 participants show that all participants could complete the task faster with training, without sacrificing accuracy on the same/different judgment task. While a majority of participants were able to direct their PRL towards the initially hidden stimulus, the ability to do so varied between participants. Specifically, 6 of 9 participants made faster saccades with training. A smaller set (4 of 9) made accurate saccades inside or close to the target area, and retained this strategy two to three months after training. Subjective reports suggest that training increased awareness of the scotoma location for some individuals. However, training did not transfer to a different visual search task. Nevertheless, our study suggests that increasing scotoma awareness and training participants to look toward their scotoma may help them acquire missing information.