There aren't any studies I have seen that show a decrease in carpal tunnel/wrist injuries due to a stretch regiment.
Several studies have shown that stretch micro-breaks are effective in reducing subjective discomfort though.
Jason Griffith
Professional Engineer
Certified Professional Ergonomist
It's recommended that for typical types of hand push buttons, you shouldn't exceed 2 lbs of force to activate. However, that's assuming it's a typical operation.
Jason Griffith, PE, CPE
The human eye can perceive at a minimum a visual angle of approximately 1 minute of arc (1 degree /3600).
However, there is a lot of environmental factors such as adequate lighting, the vision of the inspector, whether the person is searching for the error (which leads into training issues and...