Wednesday, April 2, 2025
4/2/2025
The preferred retinal locus in central vision loss - PROJECT SUMMARY/ABSTRACT People who lose their central vision due to macular disease such as age-related macular degeneration (AMD) must use their residual peripheral vision for visual tasks. Following the onset of central vision loss, most patients eventually adopt an eccentric retinal location outside the affected macular area, the preferred retinal locus (PRL), as their new reference locus for visual tasks. Little is known as to how and why a location eventually evolves into the PRL. In this project, we are going to tackle the what, where, why, how, who and when of the PRL development. The long-term goals of this project are to understand the mechanism(s) underlying the development of the PRL, and the limiting factors and potentialities of the PRL(s) for various visual tasks so that effective visual rehabilitative strategies can be developed for patients with central vision loss. The first aim of the proposed research addresses the what question. We hypothesize that there is a shift in the origin of the retinotopic reference frame from the fovea to the PRL for people with central vision loss. We will determine the retinal locus used to perform oculomotor and perceptual tasks to evaluate if the retinal locus for these tasks is shifted to a consistent location outside the scotoma with properties similar to those of the fovea. The second aim addresses the where and why questions. We hypothesize that the PRL is the location with the most optimal retinal structures/functions. Optical coherence tomography and adaptive-optics imaging will be used to measure structural properties; and acuity and sensitivity will be measured around the scotoma of participants with central vision loss. We will determine if these structural properties can predict the PRL location. The third aim addresses the how question. We will test the hypothesis that vision at the PRL can be optimized for people with central vision loss. We will measure wavefront aberrations to determine the best spectacle prescription that corrects for optical aberrations to test if this will improve visual performance for our participants. We will also devise a perceptual learning and a saccade training task to determine the effectiveness of these training regimes on improving the functional vision of our participants. The fourth aim addresses the who and when questions. We will track the changes (if any) of the structural properties in the macular region over a period of three years in a cohort of participants with early AMD who do not yet have a PRL, with the expectation that a subset of these participants will eventually develop a PRL, thus allowing us to identify who will develop a PRL and the time-course of the PRL development. Findings from this project will tell us more about the PRL — what it really represents, where it is, why a particular location evolves into the PRL, how vision can be improved or enhanced at the PRL, who will develop a PRL and the time-course of the development (when). The information combined have the potential of developing into useful rehabilitative tools that might help us predict the best location for a PRL or improve the functional vision of people with central vision loss.
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