Those tiny tubes are normal to be in your eye but you usually don’t notice them (they are body cells or proteins). Only when you are looking at something bright (eg. a completely white wall) do you see them. If you regularly see them and they dont go away if the room is less well lit then you should get it checked out though.
UK is a conplete chaos between the two. You buy liters of milk but a gallons of gas. Speeds are in miles per hour. Close distances are in meters, longer ones in miles. I have seen weight both in grams and in pounds. And then the currency is even called pound.
“How many pounds does one pound of apples cost, sir?”