Difference between vision and sight

People don’t often think of sight and vision as something different, however I want to offer a little different perspective on it, how it is affected by the brain and how the brain affects each.  

At their core, sight is the ability to see objects.  Vision is the ability to recognize objects and have some understanding of them.  This may seem pretty basic, but the understanding can get us deeper into the function of how your brain works and why vision is our most important day time sense. Let’s get sight out of the way first.  Sight is how well your retina, the cells in the back of your eye that take light, can process that light into signals that can be transmitted to your brain.  You have two types of retinal cells the rods and cones.  Rods are used for peripheral vision and seeing in the dark, and cones for fine vision like reading and processing colors.  When you go to the optometrist this is what they are evaluating.

Vision however is so much more.  With vision we are interpreting the signals sent by those rods and cones.  This means that you use your whole brain to do vision.  You see with the back part of your brain called the occipital lobe.  But then other areas also chime in, like the frontal lobe, to keep you looking at it and assign value to whether it is important, the temporal lobe lets you know if what you are looking at is making a sound to better determine if it is important, the parietal lobe and deep temporal lobe evaluate past memories if you have seen it before to know what it is.  Then your limbic brain chimes in to let you know how all that information makes you feel.  Should you run from what you are seeing, is it a friend, food, shelter, etc.  Vision allows us to have meaning and interpretation behind what we see. This is important because if your limbic brain or other areas aren’t interpreting data well than it can literally change what you are seeing. 

For instance, ever see something in the distance and get a certain feeling about it, only to get up close and realize it was nothing to worry about.  But until you were close enough, your body was sure it was the other thing.  We usually use the example of a patient in the office.  While driving down the road she saw a black lump on the side of the road.  She was sure it was a dog that had been hit, she lost her dog some months before getting hit, and immediately she got an upset stomach.  She thought she could see the tail at one point and continued to feel sicker and sicker as she got closer, that is the limbic brain, until she close enough to realize that it was a garbage bag on the side of the road.  Her sight was fine, but her vision was obscured from her limbic brain and it changed her physiology.  

So, it is important to get your sight checked by the optometrist but who is checking your checking your vision?  We do a “Vision” check utilizing the Right Eye and other things to assess how those systems are working.