C4.6.4 Where the supply of spectacles is made under the supervision of a registered professional, the supervisor retains full responsibility for the supply. The supervisor must be on the premises, aware of the procedure and in a position to intervene if necessary to ensure that no untoward consequences to the detriment of the patient can arise from the actions of such a person who is being supervised. In the case of General Optical Council v Vision Direct (1989) it was held that supervision by a dispensing optician or optometrist means that the dispensing optician or optometrist is able to exercise his or her professional skill and judgement as a clinician. It does not mean supervision by someone performing a purely clerical or even managerial function, even if the person who is performing that function happens to be a dispensing optician or optometrist.