They lost their jobs anyway and were too injured to seek other positions. Some people suggested using my left hand, but I am used to drawing with my right hand. If you can draw with a pencil and scan your design, do that. Programming your keyboard to click is also a good idea, but only if you can avoid awkward hand positions. Unfortunately, the existing alternatives to the mouse raise new ergonomic issues.
Foot pedals can lead to leg strain.
Furthermore, the click is only one part of mouse use. You still have to drag, circle, and point the mouse, all of which can lead to overusing the dominant hand. RSI is rampant among intensive mouse users, many of whom become permanently disabled and unemployable. If you already have an injury, you must find ways to avoid the mouse and other stressors, including hand-intensive activities such as bowling or playing guitar. If your job involves drawing with the mouse, I strongly suggest you rethink your career.