Mapping the binocular scotoma in macular degeneration

Abstract

When the scotoma is binocular in macular degeneration (MD), it often obscures objects of interest, causing individuals to miss information. To map the binocular scotoma as precisely as current methods that map the monocular scotoma, we propose an iterative eye-tracker method. Study participants included nine individuals with MD and four age-matched controls. We measured the extent of the monocular scotomata using a scanning laser ophthalmoscope/optical coherence tomography (SLO/OCT). Then, we precisely mapped monocular and binocular scotomata with an eye tracker, while fixation was monitored. Participants responded whenever they detected briefly flashed dots, which were first presented on a coarse grid, and then at manually selected points to refine the shape and edges of the scotoma. Monocular scotomata measured in the SLO and eye tracker are highly similar, validating the eye-tracking method for scotoma mapping. Moreover, all participants used clustered fixation loci corresponding to their dominant preferred fixation locus. Critically, for individuals with binocular scotomata, the binocular map from the eye tracker was consistent with the overlap of the monocular scotoma profiles from the SLO. Thus, eye-tracker-based perimetry offers a reliable and sensitive tool for measuring both monocular and binocular scotomata, unlike the SLO/OCT that is limited to monocular viewing.

Assessing REALTER simulator: analysis of ocular movements in simulated low-vision conditions with extended reality technology

“…The presence of a central scotoma has been observed to induce instability in the oculomotor system ( Nuthmann et al, 2022 ). Saccadic movements are also affected by the loss of central visual field, often resulting in irregular saccades and the splitting of linear saccades into smaller, irregular ones ( Vullings and Verghese, 2021 ). Subjects affected by central scotomas tend to perform a significantly higher number of saccades with larger amplitudes compared to healthy-sighted subjects ( Van der Stigchel et al, 2013 ).…”

“…Maculopathy significantly affects the oculomotor system ( Kumar and Chung, 2014 ). While saccades in healthy individuals are generally horizontally linear in magnitude, maculopathy induces multiple short saccades in various directions ( Vullings and Verghese, 2021 ). Especially during the reading of a text, poor oculomotor control induced by central scotomas leads to abnormalities in interword saccades and an increased number of regressive saccades ( Cahill et al, 2005 ).…”

Visual Field Dependence Persists in Age-Related Central Visual Field Loss

“…At SKERI, the binocular scotomata were assessed using the method in (Vullings and Verghese, 2021). 30 …”

Mapping residual stereopsis in macular degeneration

“…We used Psychtoolbox in MATLAB (MathWorks, Natick, MA) ( Brainard, 1997 ; Pelli, 1997 ) to program stimuli for the experiment. We attempted to monitor fixation of the dominant eye with the EyeLink 1000 eye tracker (SR Research, Kanata, ON, Canada) in the tower-mount configuration, which we have successfully used in other eye movement studies with maculopathy participants ( Shandize, Heinen, & Verghese, 2017 ; Vullings & Verghese, 2021 ), but the infrared signal used to control the shutters of the stereo glasses for each eye interfered with the infrared signal from the eye tracker in the tower-mount configuration. We then attempted to track fixation with the eye tracker in the table-mount configuration, but the more noisy signal associated with the table-mount configuration at the viewing distance of 40 cm and the eccentric gaze angle of some of our participants with binocular scotoma made the eye-position signals unreliable.…”