2 KudoZ points awarded for this answer. Comment: "Thanks for your answer. An applation tonometer is 圧平眼圧計. But that is not what 圧平管 is. After I asked this question I was able to find a paper written in English by the same author that had a very similar passage that described this as only "Rubber Tube". I know this is less meaningful than the true term, but I am going to use it anyway. Thanks for your help."