Blind Spot Demonstration To find your blind spot, close your left eye and stare at the cross with your right eye. Hold the book 15 to 30 cm away from your eyes and move it slowly toward and away from you until the dot disappears. The dot is now in your blind spot and not visible. At this point the vertical lines may appear as one continuous line because the visual system fills in the area occupied by the missing dot. To test your left eye’s blind spot, turn the book upside down and repeat with your right eye closed.