* There are two different categories of sub-pixel defects:
Bright Dot defect - A sub-pixel that is permanently white, red, green, or blue on a full black background. 6 or more, replace the monitor. For UltraSharp monitors (for example, U2410, U2710, 2408WFP), 1 or more, replace the monitor.
Dark Dot defect - A sub-pixel that is permanently black on a full white background. 6 or more, replace the monitor.

* A possible cure for a Stuck pixel, as reported by Forum users, is to try using Dead Pixel Tester (DPT)
http://www.dataproductservices.com/dpt
* Once downloaded, start it by double-clicking DPT.exe
* Check Auto Cycle
* Change the speed to 250 (the fastest speed in milliseconds that it changes the background color)
* Let it run for 5 minutes and see if it unstuck the pixel. If not, try 10 minutes, etc.