Eye shape and size -

 

Everyone has one eye larger than the other.  On this subject the eye on our right is clearly smaller.  You can compensate for that when shooting by shooting into the small  eye.  Usually, when someone says they have a good side, it is the side with the small eye.

 

If you shoot into the smaller eye (like the right shot) the natural distortion of the lense will make the closer eye bigger and the farther eye smaller thereby making their relative sizes match ... If you shoot into the side with the bigger eye, you will have the same effect but instead of correcting the problem it will magnify it. 

 

Shoot into the side with the small eye to make it appear bigger to match the other eye.