TY - JOUR T1 - Spatio-temporal summation of perimetric stimuli in healthy observers JF - bioRxiv DO - 10.1101/2022.08.10.503485 SP - 2022.08.10.503485 AU - Giovanni Montesano AU - Pádraig Mulholland AU - David F. Garway-Heath AU - Josephine Evans AU - Giovanni Ometto AU - David P. Crabb Y1 - 2022/01/01 UR - http://biorxiv.org/content/early/2022/08/13/2022.08.10.503485.abstract N2 - Spatial summation of perimetric stimuli have been used to derive conclusions about the spatial extent of retinal-cortical convergence, mostly from the size of the critical area of summation (Ricco’s area, RA) and critical number of Retinal Ganglion Cells (RGCs). However, spatial summation is known to change dynamically with stimulus duration. Conversely, temporal summation and critical duration also vary with stimulus size. Such an important and often neglected spatio-temporal interaction has important implications for modelling perimetric sensitivity in healthy observers and formulate hypotheses for changes measured in disease. In this work, we performed experiments on visually heathy observers confirming the interaction of stimulus size and duration in determining summation responses in photopic conditions. We then propose a simplified computational model that captures these aspects of perimetric sensitivity by modelling the total retinal input, the combined effect of stimulus size, duration and retinal cones-to-RGC ratio. We additionally show that, in the macula, the enlargement of RA with eccentricity might not correspond to a constant critical number of RGCs, as often reported, but to a constant critical total retinal input. We finally compare our results with previous literature and show possible implications for modelling disease, especially glaucoma.Competing Interest StatementG. Montesano, CenterVue (Consultant); Relayer (Owner); P. Mulholland, None; G. Ometto, Relayer (Owner); D.F. Garway-Heath, Carl Zeiss Meditec (Consultant), CenterVue (Consultant), Heidelberg Engineering (Financial support), Moorfields MDT (Patent), ANSWERS (Patent), T4 (Patent); J. Evans, None, ; D. P. Crabb, CenterVue (Consultant), ANSWERS (Patent), T4 (Patent). ER -