Does the optometrist need to know when I last had my eyes tested?
Yes. The date of the last test is important for clinical reasons.
For example, if a 70 year old patient last had an examination 6 months previously and their prescription had changed significantly, this might indicate that cataracts are developing fairly rapidly.
If the same change was observed over a 3 year period in a myopic 22 year old patient, this would be less cause for concern, because it would probably be due to an increase in simple myopia.