Unless we have a serious impairment to our visual system, vision appears quite simple. Wherever we look we see an endless stream of visual information. We can see that the sky is blue and that the leaves on the trees are turning red. We can look at someone’s face and know right away that it is someone we know. We can walk across a room and not bump into any of the furniture or the walls. We can drive a car at 60 mph, hit an oncoming tennis ball, read at a rapid pace…. None of this seems remarkable.

What is this seeing? The furniture doesn’t enter our eyes. What we see is light bouncing off the faces, furniture, cars and clouds we look at. Our world is illuminated by photons or particles of light from the sun (or artificial lighting), some of which bounce off of the furniture and enter our eyes, where they are focused and processed into what we think of as vision. From all that light bouncing off of everything in our environment we see colors, see the person about to walk into us on the sidewalk, pick up a spoon and sip our soup…

Our visual system is, in fact, bewilderingly complex, as is that of other animals. And while we are still unraveling the mysteries of the visual process, understanding the basic processes can be “eye-opening” for any of us as we navigate our world and essential for anyone whose visual system begins to go wrong.