The iStent is an extremely safe device/procedure which has virtually no complications or side-effects. Some of the occasional side-effects described include transient bleeding into the eye, infection (endophthalmitis) and transient inflammation. These side-effects occur in less than 1 / 200 cases and are extremely uncommon.
The device has proven efficacy. It has been shown in studies that average pressure reduction with the iStent is 20%. On average 66% of patients with mild or moderate glaucoma will need no further glaucoma drops after having an iStent placed.
As with all glaucoma operations, there can be no guarantee for success, as some patients will have a poor pressure reduction even with an accurately placed iStent. As with all glaucoma procedures, a small number of patients will eventually worsen despite having an initial fully functional iStent in place.