Abstract
Purpose :
Following the loss of central vision, most patients eventually adopt a retinal location outside the central scotoma for seeing — the preferred retinal locus (PRL). Little is known about how the PRL location is selected. Bernard and Chung (2018) reported better acuities at other locations around a central scotoma than at the PRL, implying that the selection of the PRL location is not driven by optimizing acuity. In this study, we used a light detection task to study whether the selection of the PRL location is driven by optimizing sensitivity.
Methods :
Sensitivity was measured at multiple retinal locations around the central scotoma of the better-seeing eye for seven participants with long-standing bilateral central vision loss (age: 57–94, logMAR acuity: 0.26–1.10). We first used an OCT to locate the foveal pit, and a MAIA microperimeter to locate the PRL and to map out the absolute central scotoma. We then identified multiple locations around the central scotoma for testing (ranged between 38 and 97 across participants). These locations were generally positioned along 12 meridians radiating from the foveal pit (30° apart), covering the region 1–5° from the edge of the scotoma. Additional locations, including some around the PRL, were also tested when necessary. Sensitivities at these locations were measured using MAIA, with the 4-2 procedure, while participants were asked to keep the fixation target visible at all times. Measurements of locations falling within the bivariate ellipse encompassing 68% of eye positions during testing were averaged to represent the sensitivity of the PRL.
Results :
Across participants, sensitivity at the PRL was not the highest among all testing locations. Sensitivities better than that at the PRL were observed at 67% (range: 42–100%) of the testing locations. These locations did not cluster around the PRL, and did not necessarily lie at the same eccentricity as the PRL. Further, sensitivities did not correlate with the eccentricities of the testing locations.
Conclusions :
Similar to the main finding of Bernard and Chung, here, we observed better sensitivities at many other locations around a central scotoma than at the PRL, implying that the selection of the PRL location is unlikely to be driven by optimizing sensitivity. It remains plausible that the selection of the PRL location is governed by multiple factors and future work is necessary for solving this puzzle.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.