The fovea is a small pale spot, about the size of a pinhead
and, on our big picture, is in the darkened area just to the
right of the optic disc - it has been electronically enhanced
in this image.
All the cone sensors of the retina are concentrated in this
area. It is totally responsible for our colour vision and our
critical vision.
Whereas large changes can affect other parts of the retina without
giving rise to visual problems, we are likely to be aware of
the tiniest changes in this region as it affects our critical
vision.