I sliced the side of my finger and had eight stitches in 2009. I did NOT have my finger hanging over the ruler but I was in a hurry. I was cutting stabilizer for an embroidery project and just slapped the ruler down and accidentally put the rotary cutter on the ruler. It quickly went sliding.
My aunt tried really hard to get me to buy something that Erica's in South Bend, Indiana was selling at a quilt show that spring. I didn't like it becaue I don't like adding another dimenison to distort my vision. I do most of my cutting in low light by choice. Anyway, my aunt really liked it but I did not. It may be what is shown above. I can't remember.
BTW, I have had a rotary cutter since 1985 and cut out everything under the sun with it - mostly clothing for the first 18 years. I only cut myself that one time. Technically I know I should stay away from sharp objects when my senses are dulled but I would never get anything done that way. One has to determine their own risks and way the cost.