Backlight Leakage
Backlight leakage refers to the problem some screens exhibit where in a darkly lit room, and with a dark image on the screen, you can clearly see areas particularly around the edges where the backlight shines through. This is a problem with the manufacturing stage and quality of the monitor build. A lot of panels will show slightly uneven backlighting, with perhaps a little light noticeable at the edges of the screen or in the corners. This is nothing really to worry about, but panel uniformity can vary from one screen to the next. Some screens on the other hand show far more severe and distracting bleed and often a return to the manufacturer is the only option for the buyer.
From tftcentral:
I'm returning a monitor due to backlight bleed. I don't believe that there should be anything particularly noticeable when forking out a few hundred quid on a monitor. I've read that some monitors' bleed stays the same, some gets worse and some get better so it's just pot luck. I don't think being unhappy with noticeable backlight bleed is being fussy at all. Your eyes are the ones that are going to be drawn to it every time you look at a dark image on the screen so if it's annoying to you, return it. Unfortunately, it's quite subjective as to whether it's seen as a fault by the retailer.
Well prepare to spend the next year or so returning monitors because most LED screens have uniformity problems... Pretty much all of them have some amount of backlight bleed in a dark room.
