I can blur my vision on command, normal?!

Yes, it is normal.

There are several systems in your eyes that all work together to allow you to see clearly.

One system, called vergence, is what "points" your eyes to what you are looking at. You use very little vergence when you look at things far away because both of your eyes can essentially be looking straight ahead. But when you need to look at something up close, like the fine print on the back of a label, your eyes actually naturally need to turn inward slightly in order to point both of your eyes at those little letters you want to read.

If the vergence system isn't working and both of your eyes aren't pointing in the same place, you will see double. This happens in people who have an eye turn except in their case, if the eye turn goes on for a very long time and happens when they are young, the brain just learns to ignore one of the eyes because it's just too darn hard to walk around seeing double all the time! The eye it ignores then becomes a "lazy eye".

However, there is another system that has to be working properly called accommodation. This is the focusing system of your eyes. Again, when you look at something far away, you don't need to focus very much at all because the object is very far away. (Think of a manual camera. You don't need to change the focus on the camera if you want to take a picture of the mountains.) But when you look at something up close, again like the fine print on a label, your focusing system increases. This keeps the letters clear for you to read.

So accommodation is responsible for keeping things clear. It focuses the eyes.
Vergence is responsible for keeping things single (so you do not see double). It "points" the eyes.

So......

When you cross your eyes on purpose, you are separating those two systems from how they normally work together. This is why things get blurry! The two systems are no longer working perfectly together so you'll either 1) see blurry or 2) see double.

Almost everyone can cross their eyes because it is simply controlled by muscles around your eye, just like you can move your arm or move your leg on command because you can control those muscles too.

But do realize there are certain visual conditions out there where vergence and/or accommodation are NOT working properly together, such as convergence insufficiency or accommodative excess. Those people have visual symptoms that require vision therapy and/or glasses to fix.

But what you are doing, totally normal!!

Kinda cool too, right?

I am an optometry intern. And I can also cross my eyes. ;)

Yes, everyone can do it. To others, it looks like you;re crossing your eyes.

If this is not what you're talking about, consult your GP!

Medical student.

yea its normal. youre basically just focusing your vision in and out. ever notice how if youre looking at something in the distance, things you see in your periferals are blurry?

yes its normal...youre simply focusing on something thats beyond what youre looking at therefore blurring whats in "front" of you

my eyes

lol, I do the same and my grandpa thought i was cross eyed.

i can blue my eyes on command without crossing them. never thought anything about it i'd say your normal ahha.