A method to characterize compensatory oculomotor strategies following simulated central vision loss

Abstract

Loss of central vision can be partially compensated by increased use of peripheral vision. For example, patients experiencing central vision loss due to disease (macular degeneration) or healthy participants trained with simulated central vision loss, tend to develop eccentric fixation spots for reading or other visual tasks. In both patients and in simulated conditions, there are substantial individual variations in the effective use of the periphery. The factors driving these individual differences are still unclear. Although early approaches have described some dimensions of these strategies, the field is still in its initial stages and important elements are often conflated when examining gaze patterns. Here, we propose a systematic approach to characterize oculomotor strategies in cases of central vision loss that distinguishes different components: saccadic re-referencing, saccadic precision, first saccade landing dispersion, fixation stability, latency of target acquisition, and percentage of trials that are useful. We tested this approach in healthy individuals trained with a gaze-contingent display obstructing the central 10 degrees of the visual field. The use of simulated scotoma helps overcome known challenges in clinical research, from recruitment and compliance to the diverse extent and nature of the visual loss. Importantly, this approach offers the ability to examine oculomotor strategies as they develop in controlled settings where viewing conditions are similar across participants. Results show substantial differences in characteristics of peripheral looking strategies, both across trials and individuals. This more complete characterization of peripheral looking strategies can help us understand individual differences in rehabilitation after central vision loss.

We don't all look the same; detailed examination of peripheral looking strategies after simulated central vision loss

“…To evaluate changes in oculomotor behavior after training with simulated central vision loss, we used four of the metrics described in Maniglia et al (2020) . We first calculated agnostic metrics (see the Supplementary Material ), and then, in cases of multiple clusters of fixations outside the scotoma, we conducted PRL-specific analyses considering the larger cluster (e.g., the main PRL), as shown in Figure 2 , right column.…”

“…Although patients with central vision loss often develop compensatory oculomotor strategies to adapt to the loss of central vision, these vary across individuals, and patients often struggle to conduct tasks of daily living such as reading, navigating, finding objects, and recognizing faces. The purpose of this paper is to apply a recently published method of characterizing oculomotor strategies after central vision loss ( Maniglia, Visscher, & Seitz, 2020 ) to understand the time course of perceptual learning of compensatory oculomotor strategies after simulated vision loss and the extent to which these strategies do or do not transfer between the trained task and an untrained task. Our hope is that, by understanding how these oculomotor strategies change through perceptual learning in cases of simulated scotomas, this could pave the way toward the development of interventions that could help train patients to better perform tasks of daily living.…”

“…In this paper, we apply a recently published method to characterize oculomotor strategies after central vision loss ( Maniglia et al, 2020 ) to understand the time course of how oculomotor behavior changes through contrast detection training in conditions of simulated central vision loss. By using this new method, we hope to achieve an in-depth classification of eye movements that disentangles a number of peripheral looking behaviors (see Figure 1 ).…”

“…We note that, although Maniglia et al (2020 ) used a portion of the same dataset, the goal of that paper was to describe, motivate, and validate the methods for describing oculomotor strategies, and it only considered the post-test data. In the current manuscript, we examine details of eye movement–related metrics as they changed during the course of perceptual learning training and how they differed between training and test sessions.…”

“…In the current manuscript, we examine details of eye movement–related metrics as they changed during the course of perceptual learning training and how they differed between training and test sessions. Figure 1 highlights the metrics from Maniglia et al (2020 ) that are applied in the current manuscript: first saccade landing dispersion, saccadic re-referencing, fixation stability, and latency of target acquisition. Figure 2 shows the training regime and the different training and testing sessions that are discussed in the current manuscript.…”