The receptionist is merely passing on what is required at renewal time. People forget to bring in their spare glasses and this holds up the medical renewal.
When you go for your first medical, some may not be aware they even need glasses. That's what the medical is for. A fact finding mission for you and the DAME.
If you do need vision correction as determined by the DAME, it will be stated on your medical certificate you get back from CASA. The requirement to carry spare glasses is NOT stated on your medical certificate.
That little gem is found in CASR 67.20 (Civil Aviation Safety Regulations 1998 Volume 2).