March 13, 2014
I’m still reading my book, The Eye: A Natural History, and finally in the last chapter. Wow, the information in it isn’t something that I can just take with a grain of salt. The reason it’s taking so long to finish is because I’m looking up so much about what I read in it. Vision and how the eyes work…there are still some mysteries to us and that mystery goes way back thousands of years. If we didn’t have to think about how things worked and went on our merry way, would we be any better off? Of course not, that wouldn’t be human (because of our curiosity for answers) but the fact that 50% of college students think that light goes out of our eyes to see rather than coming in to our eyes is just hard to believe. Superman eyes? Really, there’s a study that showed half of the college students surveyed think light comes out of our eyes so that we can see.
This is called emission theory. Not sure why it’s called a theory in wikipedia. But it was a theory hundreds and thousands of years ago. One of our great philosophers believed that, Plato. I can’t imagine what people thought a thousand years ago but things still persist. Things and thoughts were written down so that makes a lot of what someone believed to have a persistency….because it’s written down. The information does not go away or get retracted. It’s like some news reports we hear or read where something sensational happened and it made headlines. There are many occasions where the later final report clarified what actually happened in that sensational story but didn’t make headlines, rarely ever makes headlines or is even reported….unless it’s another sensational story.
Why would 50% of college students think that light comes out of our eyes to see things? I’m beginning to really wonder if Superman does have anything to do with that. Maybe there’s another situation that might reinforce this which is when a little baby plays peekaboo. If their eyes are covered they think the other person has disappeared. They don’t understand object permanence but does that linger into college in some other way?
Another interesting experience is seeing the reflection of light come out of an animals eyes at night. It’s called eyeshine. You probably know what that looks like….beams of light coming out of a cat, deer or a raccoon’s eyes. Perhaps those animal reflections are unexplained to younger people so they might believe light does come out of an animals eyes to see better. And in reality, it does come out but only because light was shined into their eyes. They have interesting retinas with tapetum lucidums that give their photoreceptors a second chance to receive light by it reflecting back instead of the light just being absorbed. Even humans have reflecting retinas, “eyeshine,” that give us a red pupil after a camera flash. See my other post about that.
Is this light coming out of eyes related to the so-called “evil eye” where one could inflict some torturous occurrence to another by staring at them? What eyes say to others is another story but you can get the feeling when someone is giving you that look. They aren’t sending any light out of their eyes to you though.
One other misconception I want to mention is that you can still drive a car if you’re dilated! I wanted to get that in here. So many times patients ask me if they can drive home after I dilate them. There are a few exceptions to this but for most people dilating isn’t anything to worry about, driving or not.
And finally, light does not come out of our eyes to see objects. It comes into our eyes. You knew that.
Here are some cool eyeshines (color of the reflection has to do with the angle and mineral structure):