A second option worth looking at when you are searching for an ergonomic mouse is the Logitech M570 Wireless Trackball. This mouse offers a unique concept with its stationary trackball, which prevents you from having to move your arm in order to move your cursor. This allows your hand to stay in a stationary position.  

The Logitech M570 Wireless Trackball mouse also features an ergonomically sculpted design, which allows your hand to sit naturally while you are using it, allowing for all day comfort. Since this mouse has a stationary trackball and is also wireless, you don’t need to worry about your desk space as much as you would for a mouse that moves around. This also gives you the ability to place the Logitech M570 Wireless Trackball wherever you can find the most natural placement for your arm and wrist.