Fig. (1) Intraocular pressure following a change in glaucoma medication regimen. The added group had brimonidine added to a prostaglandin analogue. The switched group switched from using a prostaglandin analogue to prostaglandin/timolol fixed combination eye drops. *p < 0.001 compared with pre-treatment values; **p < 0.0001 compared with pre-treatment values; IOP, intraocular pressure.