Moneo writes

There has recently been a debate centred around who is responsible if a patient takes their prescription for glasses elsewhere and pays for them and then can't see through them. I do not wish to go into the ins and outs of that particular case but it set me thinking as to just what this 'prescription' is that we give people.

Will it be correct every time? Of course it won't. There are bound to be mistakes. The bald fact is that this so called prescription is a best attempt at finding lenses for someone based upon the skills of the optometrist and the responses given by the patient during the test. It is only when the patient actually wears the prescription will both the optometrist and the patient be able to confirm that it is suitable and comfortable. Why then have we allowed ourselves to get in the ridiculous situation where we are legally obliged to hand over a specification for a patient to use without knowing whether it is suitable or not? It is because the current laws have deemed it so. Giving someone a new pair of spectacles with a prescription they cannot tolerate could potentially cause harm.