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5-year Results From the HORIZON Trial

Article Name: Long-term outcomes from the HORIZON randomized trial for a schlemm’s canal microstent in combination cataract and glaucoma surgery

Article Summary

The HORIZON trial was a prospective, multicentre, single-masked, randomized control trial that assessed the long-term safety profile and effectiveness of combined cataract surgery and Hydrus Microstent (HMS) placement in comparison to cataract surgery alone in patients with mild to moderate primary open angle glaucoma. Patients were randomized 2:1 to receive the HMS (369 eyes) vs. cataract surgery alone (187 eyes). Key outcomes of the study were long-term adverse events including corneal endothelial cell counts, surgical success rate (defined as intraocular pressure (IOP) ≤ 18 mmHg or 20% IOP reduction independent of medication use), mean IOP, repeat glaucoma surgery, and need for additional medical therapy.

Of the 556 eyes enrolled in the study, 442 (80%) achieved 5 years of follow-up. There were no clinically significant differences in best corrected visual acuity, or safety outcomes between the two groups including the rate of endothelial cell loss. A greater proportion of eyes in the HMS group maintained an IOP ≤ 18 mmHg (49.5%) compared to the isolated cataract surgery group (33.8%). Combination HMS and cataract surgery reduced dependency on IOP lowering medications and increased the likelihood of remaining “drop-free” regardless of the number of medications taken pre-operatively (66% HMS eyes were drop free vs. 46% in the cataract surgery only group). Furthermore, eyes with HMS implantation were less likely to require additional incisional glaucoma surgeries. Overall, data from the HORIZON trial supports the safety and efficacy of combination HMS and cataract surgery in patients with primary open angle glaucoma over 5 years. According to the authors, this is the longest continuous follow-up RCT for a minimally invasive glaucoma surgery to date.

Publication date: July 1st, 2022

Author: Brooklyn Rawlyk


Ahmed IIK, De Francesco T, Rhee D, McCabe C, Flowers B, Gazzard G, et al. Long-term outcomes

from the HORIZON randomized trial for a schlemm’s canal microstent in combination cataract and glaucoma surgery. Ophthalmology [Internet]. 2022;129(7):742–51. Available from:


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