Novel strategies to enhance the visual performance of the visually impaired

Abstract

Patients with central vision loss use alternative retinal locations to compensate for the lack of visual input. This retinal location is referred to as preferred retinal locus of fixation. The mechanisms underlying the PRL development are not fully understood and patients may not always select the most beneficial PRLs for the performance of a specific visual task. This work addressed the question whether the selection of PRL location can be influenced and whether the influenced PRL can be transferred to daily visual tasks. Furthermore, the relationship between the abilities to deploy attention in the visual field and the PRL development was investigated. The participants were normally sighted subjects that underwent a simulation of central scotoma. To induce the PRL, a stimulus that evoked a saccade was presented and subjects had to perform a discrimination task while systematic stimulus relocation were applied to the stimuli. After four training sessions, the final PRL location was assessed. In addition, subjects performed a pursuit task, and two different reading tasks to address whether the induced PRL can be transferred to daily visual tasks. The attention hypothesis was addressed in the third study with a new cohort of participants. Sustained attention was compared to the PRL developed after two sessions of central scotoma simulation. The results showed that systematic stimulus relocations can be used to influence the development of the PRL and that the induced PRL further transfers to some daily visual tasks. Furthermore, the attentional capabilities of the subjects were shown to be related to the PRL development. The relationship between attention and PRL development could be used as an indicator of potential PRL locations when patients are at early stages of their disease. This information would allow the prediction of beneficial PRL developments and can help for the decision on whether they need to be further trained. In case that training strategies are needed, systematical stimulus relocations can be a good starting point to induce the PRL. With the knowledge that induced PRLs can be transferred to other visual tasks, PRLs can be induced and be further used in everyday life situations.