Thanks Oak, the test I did on some old and useless pairs was quite positive. I put some fingerprints on the lenses and with the temperature between 45-50 degrees celsius they were gone. It was also that first test session that I found out that the timer didn't work.
There was some other nasty stuff on the glasses though that remained. I am contemplating if some ecological dish washing solution might also help, we have one here from a brand called Sonnett and they only use plant based stuff in it. Comparing it to the lens cleaning solutions it seems like a way more pure solution than the solutions. It is this stuff: https://gimmethegoodstuff.org/store/sonett-dish-soap/
However I am always a bit afraid of using solutions on my eyewear. I am curious what you think.