It is good practice to follow up equivocal results from non-contact tonometry with contact applanation tonometry. If you are using non-contact tonometry, before considering referral you should take four readings per eye. In England, Wales and Northern Ireland, in the absence of other signs of glaucoma, you should refer the patient for further assessment only when the mean of the IOP readings is 24mmHg or above. You should advise people with IOP below 24mmHg to continue with their routine eye examinations. In Scotland you should follow SIGN guidelines.