Take your optical prescription if you have one or they will be happy for you to take an in-store sight test. The optician can also measure the strength of your glasses and make equivalent glass for your chosen frames. Normal glass is ready within an hour and bifocals within a day or two.
You’ll need to be a patient haggler if you want to get the best prices. Here are a few tips:
Go early in the day.
Go round all the floors to get an idea of what’s on offer before you opt for a particular shop. It might be more expensive on the ground floor.
Buy more than one pair to get an even better discount e.g. sunglasses with polished glass.
Take cash with you. Many shops do not accept cards.