iStent inject in phakic open angle glaucoma

The effectiveness and complication profile of the iStent inject implantation among different open angle glaucoma subgroups were analyzed.

In this retrospective cohort outcome study, 35 consecutive patients suffering from glaucoma (primary open angle glaucoma (POAG) N = 17, pseudoexfoliation glaucoma (PEX) N = 15, and pigmentary glaucoma (PG) N = 3) were treated with the iStent inject. The intraocular pressure (IOP) and the number of antiglaucoma medications before and after surgery were evaluated.

In POAG, the mean IOP at 6 months measured 14.19 ± 1.38 mmHg with an average decrease of 33 % from preoperative IOP (p < 0.001), and 15.33 ± 1.07 mmHg with an average decrease of 35 % in PEX (p < 0.001), respectively. The number of antiglaucoma medications significantly decreased from 2.19 ± 0.91 to 0.88 ± 0.62 in POAG (p < 0.001) and from 2.33 ± 1.23 to 1.04 ± 0.30 in PEX (p < 0.001) after 6 months. In PG, IOP before surgery was 28.31 ± 3.21 mmHg and the number of antiglaucoma medications was 3.66 ± 0.57. One day after surgery, IOP decreased significantly to 12.33 mmHg ± 4.93 (p < 0.001). Within four weeks after surgery, IOP was raised above 30 mmHg in every patient. To exclude a steroid response, topical steroids were stopped, but IOP did not decrease. To exclude blockage, Nd:YAG – laser treatment of the visible opening of the iStents was performed. Since the IOP stayed high and escalation of antiglaucoma medication was insufficient to control IOP, trabeculectomy was performed.

In conclusion, implantation of the iStent inject has the ability to lower the postoperative IOP significantly in POAG and PEX after a short follow-up of 6 months with a favorable risk profile. However, limitation of this surgical procedure in phakic PG may exist and need to be investigated in further studies.