How dangerous is sunbed UV to the eyes?

I always use the special goggles when I use my sunbed, but I was wondering just how dangerous it is if someone didn’t. Is it like looking at an eclipse where you can go blind almost immediately? Or is the concern more for repeated exposure. What if someone skipped the goggles for a single session? What about when I was troubleshooting a wiring problem (I took it apart to clean it and got the sockets back in the wrong order and I turned it on just long enough to see if the stupid lamps are lighting now. (10-20 seconds).