I went to the opticians today as I wanted some new glasses as my current ones are 3 years old. Optician said my sight was stable, but when I've got home I've noticed there was a slight change (-3 before , now -2.5) However, my new glasses have been ordered using the strength of my current glasses which I didn't realize when I was in there or I'd have questioned it. She did ask if I had any problems with them which I don't. They are varifocals. Is there a reason why they wouldn't have changed them or do you think it's a mistake?