Role of parafovea in blur perception

7 pags., 7 figs. -- Open Access funded by Creative Commons Atribution Licence 4.0The blur experienced by our visual system is not uniform across the visual field. Additionally, lens designs with variable power profile such as contact lenses used in presbyopia correction and to control myopia progression create variable blur from the fovea to the periphery. The perceptual changes associated with varying blur profile across the visual field are unclear. We therefore measured the perceived neutral focus with images of different angular subtense (from 4° to 20°) and found that the amount of blur, for which focus is perceived as neutral, increases when the stimulus was extended to cover the parafovea. We also studied the changes in central perceived neutral focus after adaptation to images with similar magnitude of optical blur across the image or varying blur from center to the periphery. Altering the blur in the periphery had little or no effect on the shift of perceived neutral focus following adaptation to normal/blurred central images. These perceptual outcomes should be considered while designing bifocal optical solutions for myopia or presbyopia.This work was supported by the European Research Council under the 7th Framework Programme through the Marie Curie Initial Training Network OpAL (PITNGA- 2010-264605), the Swedish Research Council (621-2011-4094), European Union’s Seventh Framework Programme (FP7/2007-2013), ERC Grant Agreement (ERC-2011- AdC 294099), Spanish Government grants FIS2011-25637 and FIS2014-56643.Peer Reviewe