Just in case, please be careful.
The convenience of using optical mouse eventually caused dangerous side effect. After Three years from the first launch by microsoft, have been found thousand of cases - hands tissue caused by mouse radiation.
Optical Mouse works by release Electromagnetic high frequency to the lower surface under it. This frequency much higher than the frequency use for handphone. As it has been known that human hand and wrist contains lot of important nerve connected to brain. According to WHO, the radiation from Optical Mouse is 5 times stonger than using handphone. These radiation is even worse for those product with lower quality ( non branded mouse ), since they use weaker shield to protect customer wrist.
WHO, GreenPeace, and CNN have stopped the usage of Optical mouse in their whole office. Meanwhile Microsoft and IBM have allocate 2 billion of US Dollar, in joint venture to make a safer pointing device. Big Hardware Industries in China and Taiwan are trying to hide all fact related to this things. While in the market, most of optical mouse sold old were coming from their product. To avoid this, try to reduce using mouse. learn how to use hot key (i.e Ctrl-V, CTRL-C for paste and copy ) Use back your old model of mouse ( with the tracking ball).