I saw this on Fb, my ds3 had exactly the same injury last year.... Caused by... Lego! His brother fired s piece of Lego with a little plastic catapult type toy and it hit ds3 in the eye. His eye filled with blood, it was horrible. Took him straight to a&e and he was there all nigut and they wanted to admit him, in the end he was allowed home but was on strict bed rest for 6-8wks and had daily trips to the hospital, then every other day and then a few times a week etc. Gradually the blood and clot dispersed but they were very worried it would make his retina detach.
Now almost a year later and his vision is fine but he still needs check ups as the pupil is slightly enlarged and the pressure in that eye is higher than it should be. He had months of various eye drops etc.
It's an awful injury but just like my son it was a fluke injury. We didn't ban Lego and we won't be banning loom bands, I will tell them to be careful and supervise them.
I hope the little boy recovers fully but this really was just an accident, no need to ban loom bands.