Does anyone know if you can amend your signing to the donor register?

When I registered to be an organ donor, I said ‘no’ to donating my corneas cause I thought it was far too freaky for someone to get your dead eyes.

But Kerr has something called keratoconus which is a defect on your corneas which basically causes you to gradually go blind. He’s blind in his left eye at the moment, and it’s starting to effect his right eye now. He’ll be able to get a cornea transplant though which will enable him to see again. I think knowing someone who will one day benefit from it has just made me change my mind about it. It’s still weird to donate your eyeballs, but I won’t exactly be needing them and giving someone the gift of their sight back is surely the most amazing thing to do?

So idk, can you change it?