Buying the comprehensive package when you needed a refraction
If you are young, healthy and simply need updated glasses, the full screening tier is usually money spent on reassurance rather than need. Match scope to situation: screening earns its price for over-60s, diabetics, and anyone with a glaucoma family history — not for every routine prescription top-up.
Accepting a verbal prescription or a 'we'll make your glasses' promise
Without a complete written prescription including pupillary distance, you are captive to the tester's own glasses pricing. The written document is what makes the market work for you — any optical shop can fill it. No paper, no payment.
Skipping the licence check because the price was good
An unlicensed test is the most expensive kind: a wrong prescription means headaches and wasted glasses, and an unqualified tester can miss signs that needed a doctor. Verifying a DHA, DoH or MOHAP licence takes two minutes. Booking through a platform that verifies vendors first handles the initial filter, but asking directly costs nothing.