The retina itself is a complex tiling of photoreceptors. These photoreceptors are known as rods and cones . When these photoreceptors are stimulated by light, they produce electrical signals that are transmitted to the brain via the optic nerve . The location of the optic nerve on the retina obviously prohibits the existence of photoreceptors at this point. This point is known as the blind spot and any light that falls upon it is not perceived by the viewer.
Most people are unaware of their blind spot, although it is easy to demonstrate that it exists.
And its existence has been known about for many years as it is reputed that the executioners in France during the revolution used to place their victim so that his or her head fell onto the blind spot, thus illiciting a pre-guillotine perception of the poor character without a head. The rods and cones do not have a continuous physical link to the optic nerve fibres. Rather, they communicate through three distinct layers of cells, via junctions known as synapses . These layers of cells connect the rods and cones to the ganglion cells , which respond to the photostimulus according to a certain receptive field . We can see from Figure 2 that the rods and cones are at the back of the retina.