Many times when I go to a doctor I am intimidated by all the big instruments in the room. If I don't know how they operate or what they do, I can be scared before the exam even begins.
Even though a keratometer can look big and intimidating, I am not bothered by these machines at all. All I have to do is sit up and look through the lenses and answer the questions.
It would be interesting to know how much one of these instruments costs. I am sure it is not cheap, but an eye doctor wouldn't be able to practice without one of these in his office.