I'm getting some D4 (ring finger) fingertip numbness from the DIP onwards, likely from using a desktop mouse too much. A wee bit in D2 (index finger). Looking for mouse alternatives. Will consider getting new keyboards - USB only (not a fan of replacing batteries in devices). I've bought two things already. http://www.ergonomictouchpad.com/ergonomic_touchpad.php and another USB Touchpad. Still looking for more alternatives. I've tried mousing with my opposite (left) hand. Learning to grab the mouse differently would probably help too. A different shaped mouse that won't enable me to put pressure on the mouse with the ring finger would help.
I think my sore finger has trained my body to not grip the mouse as hard. The touchpad is great, but doesn't replace the scroll wheel well. I'm surprised how much I use the mouse wheel for browser scrolling.
Might look for a mouse wheel on a keyboard, far right side would be ideal - or maybe far left and use my left hand.
Perhaps use a smaller mouse. I use a MS bluetooth mouse and I find that my ring finger pulp is touching the mouse. Not on the lateral aspect of the finger.