Scotoma awareness: a novel protocol to induce fast development of a Preferred retinal locus (PRL) in patients with central vision loss

Pathologies affecting central vision, such as Macular degeneration (MD), represents a growing health concern worldwide. These patients, deprived of central vision, tend to adopt spontaneous compensatory strategies, including the development of an eccentric locus of fixation, called preferred retinal locus (PRL). However, clinical evidence indicates that the process is often slow, taking up months, with some patients not developing a PRL at all. Developing a PRL seems to be one of the most effective compensatory strategies in MD, thus understanding mechanisms of PRL development has important translational value. Studies on MD are made difficult by several issues, including recruitment, compliance and heterogeneity, scotoma size. In recent years, eyetracking-guided, gaze-contingent simulation of central vision loss in healthy vision individuals has been used to understand oculomotor characteristics associated with central vision loss and test possible training intervention. In these studies, a circular occluder obstructing central vision is generated in real time on a computer screen while participants are engaged in visual tasks. Evidence from this paradigm suggests that MD-like oculomotor behavior, such as the development of a PRL, can be observed. Crucially, unlike in MD, this happens within few hours of exposure to the simulated scotoma. It has been suggested that the characteristics of the simulated scotoma play a role in this difference. Indeed, MD patients are often unaware of the location, size, and shape of their scotoma, unlike in simulated scotoma studies in which these features are readily available. Here, we trained MD patients with a gaze-contingent display that visualized their retinal scotoma on screen, with the goal of increasing their awareness of its characteristics. Behavioral and oculomotor changes following training, as measured by a series of assessments collected before and after training, will will be discussed. This promising technique could accelerate functional adaptation to central vision loss in clinical populations.