Please tell me that this is just dirt and not LED failing.
I own Thunderbolt 27" 2012 http://store.apple.com/us/product/MC914LL/B/apple-thunderbolt-display-27-inch
for few years now and this purple cloud seems like it is spreading.
Do you think that this could help ?
https://www.youtube.com/watch?v=ONCdGHe0Uxs
Any help is appreciated!