If the system is under warranty, call Dell for a screen replacement.  If not, and you want to replace it yourself, [URL] (they will also provide labor for a flat fee).  
Recently a discolouration gradually takes over the corners of my screen. It's either not there or barely visible on startup and increases in intensity the longer I use my laptop. Looks red against darker colours and blue against lighter. I've had this device for about 2 years now, and the warranty has sadly expired. Does anyone know what the issue could be?  Also, I'm not sure if this is relevant, but this device also has a slight overheating (nothing disruptive, performance isn't affected, at least in an obvious way?) and a pretty loud fan noise at times, so I don't know; maybe it could be related. Attached are pictures of it at the brightest it's been. [IMAGE]
Inspiron 3493 / Discolouration on the corners of my screen