How to tell if a parrot is partially sighted?

[JaydeParrot]

I have two Sennies, I used to have them both flighted but then had to have one of them clipped.

His name is Hide, the reason I had him clipped is because it's terrifying to watch him fly, he kept flying head first into walls, cupboards, e.t.c, and yet would follow my hand with his face if I waved or moved it infront of him.

I previously asked some advise about clipping (to clip or not to clip) on this site and recieved responces from everone saying, DO NOT clip, teach him to fly instead. I got a small perch and taught him to jump to my arm from the perch, I could only ever get him to fly about an arms length and a half from the perch to me, any further and he'd either refuse or fly to me or sort of fly into me rather than landing on my arm.

I was keen not to clip him but he kept flying into everything (he wouldn't even try to slow down, it was like he wasn't seeing the walls), eventually one day, he jumped off the top of his cage, flew about 3 meters across the room, took a sudden turn to the right, flew another 1 and a half meters and (headbutted) hit the wooden headboard of an old piano, he slid and fell down to the keys, he rolled off the keys and hit the floor, he stayed there for a bit until I put a rope perch down and put him back inside his cage. I decided then that it's impossible to train a dead bird, so I had his wings clipped and made even more of an improvement on his taming and training.

Trouble is, he's slowly growing back his feathers (which in some ways is great) and I'm worried that if I let him become fully feathered again he'll keep doing damage to himself, possibly even killing himself as he never seems to realise he going towards a wall.

He's already tried a few disatorous flights including flying from my shoulder to his cage, somehow managing to fly over his cage and falling behind the cupboard his cage is against, and also when he flew out of his cage across the room and went head first into a switched off radiator.

My other Sennie can fly perfectly and never bumps into anything.

It doesn't make any sense, Hide can see a hand coming towards him and can fly to a close arm, is it possible he could be short sighted? How could I test this?

Many thanks for any and all responses or ideas you might have...