Monday, August 31, 2015

Medical Mondays: Having Fun With Blind Spots

There are so many little quirks of normalcy in your body. Maybe I'm well-suited to being a doctor since I find most of these endearing and fun (I'd entertain myself during boring lectures by finding the valves in my wrist veins, forcing the blood to flow backwards and making them pop out like...okay, never mind. You get the idea.)

I'd also have fun with finding my blind spots. It's kind of cool to watch your body parts disappear on purpose.

Let me explain.

Yes, you and everyone else have a blind spot. Two, in fact.  Here's how it works. The main nerve of your eye, the optic nerve, has to pass through the back of your eyeball to connect to your brain. The back inner surface of your eyeball is the retina, filled with photosensitive cells that help you see images. But in that one area where the optic nerve passes,  there are no cells with the ability to detect light and images. Why have you never noticed? Well, your brain does a great job of "assuming" what should belong in that blinded area, so you never notice. Also, with two eyes, they compensate for each other's blind spot.

Here's how to see your blind spot in action. 
1. Cover your left eye with your left hand.
2. Hold out your right arm, and with your right hand, make the "bull horns" sign (pointer and pinkie finger raised, palm facing away from you).
3. Stare at your pointer finger nail with your right eye, and slowly bring your hand closer. Keep your eye on your pointer finger nail the whole time.
4. At some point, the tip of your pinkie will disappear. Viola! That's evidence of your blind spot. (If this doesn't work, here's another method that's pretty cool.)

I'm not quite sure how you writers will end up using this in your stories, but it sure is entertaining when you're procrastinating or in a boring meeting. Just know that people will wonder why you're making random hand gestures for no apparent reason. Heh.

Also? Only vertebrates have this issue. The octopus does not have a blind spot. Have fun with that random, somewhat useless factoid today! Cheers!


Alex J. Cavanaugh said...

Mine didn't disappear. I'll have to try the other test.
An octopus doesn't have a blind spot? I wonder if that makes him a better driver?

Dianne K. Salerni said...

I did it, but it was hard to notice at first -- like my brain wanted me to ignore that the tip of the finger had vanished. The rest of my finger was there. My brain wanted to pretend the tip was there, too.

Deb Salisbury said...

How cool! I can't make it work, I think because I can't stay focused on my first finger.

No, wait! If I tilt my bifocals to adjust for the distance change, it does work after all. Fun trick!

Angela Brown said...

I'm sure there is some way to use this blind spot nugget, like some thriller where the victim is wearing an eye patch and notciing for the first time how they can see and not see things at times that they could see before because of that blind spot issue.

Krispy said...

Better watch out for those octopi! They'll always see you coming. ;)

J E Oneil said...

Blind spots are weird. Or rather, the brain is weird for filling things in when it can't "see" something. And the fact that octopuses don't have this issue is only further proof of the upcoming cephalopod revolution.

SA Larsenッ said...

My brain just assumes what should be there. Now that is very cool! The way you've explained it makes perfect sense. I just never thought about it before.

Southpaw HR Sinclair said...

"...forcing the blood to flow backwards and making them pop out like..." You must be a riot at a party! :)

Eva Inka Nurmaisya said...

Banned complain !! Complaining only causes life and mind become more severe. Enjoy the rhythm of the problems faced. No matter ga life, not a problem not learn, so enjoy it :)

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