The optician will have to move very close to you, with their face near to your face. This is so they can see right into your eyes. You will be asked to look up and down, right and left while the optician looks into your eyes. You may be asked lots of questions. Don't worry if you can't answer them all.
Some opticians use machines or computers in eye tests.
With some machines, you have to put your chin on a chin-rest. Some tests are more like games. In one test, the optician puffs some air into your eyes quickly. The optician has a letter chart on the wall. It doesn't matter if you don't know your letters.