The electro luminescent panel used for backlighting on Apple Newton devices loses brightness over time. Initially, a new panel loses a percentage of brightness in the first few hours of its use. Then it loses brightness at a slower rate with half brightness still available after thousands of hours of use. This slow loss of brightness is measurable with calibrated instruments, but the rate of change is not noticeable to most MessagePad 2x00 users.
This same information applies to the Apple MessagePad 130 and eMate 300 devices.