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Rong Liu, MiYoung Kwon; Relationships between retinal ganglion cells, Ricco's area and crowding zone. Journal of Vision 2017;17(10):369. doi: https://doi.org/10.1167/17.10.369.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies reported enlargements in the area of complete spatial summation (Ricco's area) for luminance detection in response to loss of Retinal Ganglion Cells (Redmond et al., 2010). While the finding suggests the integrity of RGCs may alter spatial pooling properties, little is known about its impact on the pooling mechanisms of complex object recognition. Here we examine the relationships between RGC layer thickness, Ricco's area and crowding zone. Ten normally-sighted subjects participated in the study. For Ricco's area, a subject's contrast detection threshold was measured using a luminance-disc with varying diameter. Two-limbed functions were fitted to the data of log detection threshold versus log stimulus area. Ricco's area was defined as the breakpoint of the two-limbed function. For crowding zone, a subject's contrast recognition threshold was measured using a flanked letter with varying center-to-center spacing between the target and flankers. Clipped lines were fitted to the data of log recognition threshold versus spacing. Crowding zone was defined as the minimum spacing that yields no threshold elevation in the fit. Measurements were made at 4 locations (at the eccentricity 8.5°). The RGC plus inner plexiform (RGC+) layer thickness in the central 20° visual-field was measured by Spectral-Domain Optical Coherence Tomography. We found that the RGC+ layer thickness correlated with both Ricco's area (r=−0.58,p< 0.01), and crowding zone (r=−0.31, p=0.05). A significant correlation between Ricco's area and crowding zone was also found (r=0.58,p< 0.01). Regression analysis showed a decrease of 1 μm in the RGC+ layer thickness enlarges crowding zone by 0.02° while an increase of 1° in Ricco's area (in diameter) enlarges crowding zone by 4°. Our results demonstrated close relationships between RGCs, Ricco's area and crowding zone even in healthy eyes. Our findings further support the view that changes in RGCs may alter the properties of spatial integration zone.
Meeting abstract presented at VSS 2017
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