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Glaucoma Gel Implant Learning Curve in a Teaching Tertiary Hospital

Marques, Raquel Esteves, MD*,†; Ferreira, Nuno Pinto, MD*,†; Sousa, David Cordeiro, MD*,†,‡; Pinto, Joana, MD*,†; Barata, André, MD*,†; Sens, Paula, MD*,†; Abegão Pinto, Luís, MD, PhD*,†,‡

doi: 10.1097/IJG.0000000000001107
Original Studies

Purpose: The XEN gel stent is a minimally invasive surgical device aimed at creating a subconjunctival drainage of aqueous humor, thereby reducing intraocular pressure (IOP). Being a novel device, doubts remain with regard to the efficacy and safety of its implantation in the early stage of new users. This paper illustrates the XEN implantation learning curve, assessed through several surgeons of different expertise.

Methods: This was a retrospective study on the first 6 XEN implants performed by each of the 10 certified ophthalmic surgeons. Simultaneous cataract surgery was allowed (phaco-XEN). Primary outcomes were as follows: surgical time; intraoperative and postoperative surgical complications. Secondary outcomes were as follows: IOP; the number of topical drugs in use; the need for needling procedures. Outcome data were collected preoperatively and at postoperative days 1, 7, 15, 30, 60, and 90. Statistical analysis was performed with STATA 14.1 and SPSS.

Results: Sixty patients were included (56.7% female patients). Mean age was 73 years (45 to 89). Mean preoperative IOP was 23.8±8.95 mm Hg. From the included patients, 29 (48.3%) were submitted to simple XEN implant and 31 (51.7%) to phaco-XEN. In both groups, mean surgical time decreased by 9 minutes throughout the 6-implant learning curve. Final IOP was 15±7.27 mm Hg in the stent group (−43% than baseline), and 14.92±3.32 mm Hg in the phaco-XEN group (−16% than baseline). On average, patients decreased 2 topical IOP-lowering drugs. Needling procedures were performed in 17 patients (28.3%).

Conclusions: XEN gel stent was associated with a fast learning curve, by both experienced surgeons and novice residents. By the sixth implant, both groups had considerably decreased mean surgical time and complication rates.

*Department of Ophthalmology, Hospital Santa Maria

Department of Ophthalmology Clinic, Faculdade de Medicina, Universidade de Lisboa

Visual Sciences Study Center, CECV, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal

R.E.M. and N.P.F. are co-first authors.

No funding was received from the National Institutes of Health (NIH); Wellcome Trust; Howard Hughes Medical Institute (HHMI); or others. All stakeholders in the conduct of this study are listed as authors. No external contributions were received for the conduct of the study, statistical analysis, medical writing, or counseling.

Disclosure: L.A.P. received fees as a lecturer for Allergan. The remaining authors declare no conflict of interest.

Reprints: Luís Abegão Pinto, MD, PhD, Hospital de Santa Maria, Departamento de Oftalmologia, Av. Prof. Egas Moniz, 1649-035 Lisboa, Portugal (e-mail:

Received July 18, 2018

Accepted September 22, 2018

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