My 7yo son has in the past month mentioned a number of times that he will suddenly see things 'smaller than normal'. The disturbance usually lasts only 5 minutes or so. He feels no pain or discomfort, can walk, run and jump with no problem while it's happening. He can read as it's happening. He says it happens mostly at night, though it has also happened when he is playing the piano, but it does not adversely affect his playing. It does not happen everyday or night, but it is always the same when it does occur: everything looks smaller than it should. To look at him, and his eyes as it's happening, he looks completely normal. After five or so minutes, everything suddenly goes back to normal.