At what age does a baby's brain reverse the eye's inverted image? And if an adult would wear eyeglasses that invert the image of the World, when will that inversion be counteracted again? Will it occur suddenly?

An image focused by the human eye on the retina is ALWAYS inverted: top for bottom; right for left. This was true at birth and continues throughout life.

The reason for this is just the anatomical nature of the optics of the eye and its lens system. You would think we would always see things as "upside down" and continually have problems navigating and dealing with objects coming at us, but no. The part of the brain that assembles visual data into a meaningful and useful picture of the world out there recognizes "upside-down" as normal. So we go on to learn eye/hand coordination and such within this "flipped" visual world.

So what would happen if suddenly we could make the eye see everything "right?" It would seem a totally flipped reversal of normal! A famous psychology experiment in the mid-20th century by an Austrian doctor involved building a pair of special "glasses" that inverted and flipped right-for-left the image his subjects saw through each eye. At first they would stumble and react in a completely disoriented fashion as you would expect. But within a few days, they were able to gradually see this inverted world as completely normal, even to the point of riding bicycles through traffic!

The point is that what we see "out there" is not what is truly there, but rather a reasonably useful, virtual scene our brain and body projects onto the world so as to make maximal sense of it.

_Written by J. Trevor Woodhams, M.D. - Chief of Surgery, Woodhams Eye Clinic