You can prove to yourself that this part of the retina is, indeed, blind. Try the demonstration . To see a schematic representation of why the white spot disappears when you are at different distances from the screen click on further explanation . But first let me just say that the reason that the white spot disappears is that when you look at one of the numbers and are the correct distance away from the screen the image of the white spot will fall exactly on that part of the retina that does not have any receptors. Consequently, you can not see it.