Long-term Outcomes from the HORIZON Randomized Trial for a Schlemm's Canal Microstent in Combination Cataract and Glaucoma Surgery.

Purpose

To present the 5-year results of the HORIZON trial comparing cataract surgery (CS) combined with an intracanalicular microstent with CS alone.

Design

Prospective, multicenter, controlled randomized clinical trial.

Participants

Patients with cataract and primary open-angle glaucoma treated with 1 or more glaucoma medications, washed-out diurnal intraocular pressure (DIOP) of 22 to 34 mmHg, and no prior incisional glaucoma surgery.

Methods

Eyes were randomized 2:1 to receive a Hydrus Microstent (HMS; Ivantis, Inc) or no stent after successful CS.

Main outcome measures

Intraocular pressure (IOP), glaucoma medication use, repeat glaucoma surgery, visual acuity, visual field, procedure-related adverse events, and corneal endothelial cell counts.

Results

Three hundred sixty-nine eyes were randomized to HMS treatment, and 187 eyes were randomized to CS only. Study groups were well matched for preoperative IOP, medication use, washed-out DIOP, and glaucoma severity. Five-year follow-up was completed in 80% of patients. At 5 years, the HMS group included a higher proportion of eyes with IOP of 18 mmHg or less without medications than the CS group (49.5% vs. 33.8%; P = 0.003), as well as a greater likelihood of IOP reduction of 20% or more without medications than the CS group (54.2% vs. 32.8%; P < 0.001). The number of glaucoma medications was 0.5 ± 0.9 in the HMS group and 0.9 ± 0.9 in the CS group (P < 0.001), and 66% of eyes in the HMS group were medication free compared with 46% in the CS group (P < 0.001). The cumulative risk of incisional glaucoma surgery was lower in the HMS group (2.4% vs. 6.2%; P = 0.027, log-rank test). No clinical or statistically significant differences were found in the rate of endothelial cell loss from 3 to 60 months between the HMS and CS alone groups (P = 0.261).

Conclusions

The addition of a Schlemm's canal microstent in conjunction with CS was safe, resulted in lowered IOP and medication use, and reduced the need for postoperative incisional glaucoma filtration surgery compared with CS after 5 years. Long-term presence of the implant did not affect the corneal endothelium adversely.