Safety And Efficacy Of The Hydrus Microstent During The Initial Learning Curve

To examine the safety and efficacy of Hydrus Microstent during the learning curve of surgeons new to the procedure.

A single centre university hospital in the UK (Princess Alexandra Eye Pavilion, Edinburgh).

A retrospective study including a consecutive series of the first 38 Hydrus procedures performed by 3 surgeons. Two were experienced cataract and glaucoma surgeons with previous experience of MIGS but not Hydrus and one a glaucoma fellow. In 37 cases Hydrus was combined with cataract surgery. Patients were followed for a minimum of 3 months, with the primary outcomes percentage and absolute change in IOP at time of listing for surgery compared to the visit after and closest to 3 months post-op. The relationship between order of surgery and IOP reduction was examined using regression analyses.

Mean baseline IOP was 20.5±6.5 mmHg (range 11-35mmHg), using an average of 2.0 topical medications. Average mean deviation (MD) was -9.9±7.4dB. Peak IOP prior to surgery was 26.3±5.8 mmHg. Average IOP at 3 months was 14.8±3.6 mmHg, significantly lower than baseline (P<0.001). 29 of 38 eyes (81.6%) had ≥20% reduction in IOP on the same or fewer medications. Average reduction in IOP was 23.3±27.1% (5.7±6.7 mmHg), with an average reduction of 1.4±1.2 medications. Eyes with higher baseline IOP had significantly greater IOP reduction (0.9, 95% CI 0.7 to 1.1 mmHg, greater IOP reduction per 1mmHg higher baseline IOP, P<0.001). Surgeon experience did not significantly influence efficacy. Two patients had transient hyphaema resolving by 1 week.

Surgeon experience during the initial learning curve for Hydrus had no apparent effect on efficacy or safety at 3 months. The study was limited by lack of corneal endothelial cell measurements however 5-year data from the HORIZON study indicated a high level of corneal safety even with long-term presence of the implant.