This literature review in Current Opinion in Ophthalmology reports:
There are sufficient data to suggest that cataract surgery provides a lowering effect on IOP in the long term. This effect appears to be proportional to preoperative IOP. Eyes with higher preoperative IOP have the greatest average lowering, whereas eyes with IOP in the lower range of statistically normal tend to have an IOP that is unchanged from baseline or even higher following cataract surgery. In patients with narrow angles, the IOP-lowering effect appears to also be proportional to the degree of anterior chamber deepening induced by cataract surgery.