Rapid learning curve assessment in an ex vivo training system for microincisional glaucoma surgery

Wang, Chao; Dang, Yalong; Waxman, Susannah; Parikh, Hardik; Bussel, Igor I.; Loewen, Ralitsa T.; Xia, Xiaobo; Lathrop, Kira L.; Bilonick, Richard A.; Loewen, Nils A.

doi:10.7287/peerj.preprints.2745v1

Cited by 6 publications

(11 citation statements)

References 1 publication

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“…In this study, we hypothesized that the intraoperative anterior chamber stability could be described and quantified with AS-OCT. We have comprehensive experience with an extensive range of angle surgical modalities both in training models [11,12] and in our patients [18–20]. As surgeon trainers, we are deeply familiar with the challenges of visualizing the target structure during surgery [1,2].…”

Section: Discussionmentioning

confidence: 99%

“…We employed a microsphere-based canalogram in this study that represents a simplified, less time dependent method [11,13] compared to fluorescein canalograms that require careful timing but have a high temporal and spatial resolution [13,15]. In comparison, the fluorescent spheres indicate flow only after a direct connection to the downstream drainage system is obtained.…”

Section: Discussionmentioning

confidence: 99%

“…This number was based on our prior studies [11–13] to maximize same-day comprehensive structure and function assays of eye pairs while providing a sufficient power to discover an outflow difference. They were prepared by removing excessive extraocular tissues and trimming the conjunctiva along the equator of the eyes.…”

Section: Methodsmentioning

confidence: 99%

“…Enhancement of conventional aqueous outflow was estimated by measuring the extent to which fluorescent spheres were able to access the outflow tract after ab interno trabeculectomy as described [11,13] with minor modifications. Briefly, the corneal incisions were sealed with cyanoacrylate after TM ablation, the anterior chamber was cannulated with a 20-gauge hypodermic needle (150906, Exelint International, Redondo Beach, CA) and infused with carboxylated, yellow-green fluorescent 0.5 micron microspheres (100 times dilution in DMEM, F8813, Thermo Fisher, Waltham, MA) using a gravity perfusion system set to 15 mmHg.…”

Section: Methodsmentioning

confidence: 99%

“…Until recently, the only system that maintained the anterior chamber actively with an irrigation and aspiration system was the Trabectome (Neomedix Inc.; Tustin, CA, United States), while the other surgical modalities used a viscoelastic device. Although these chamber maintaining techniques may seem interchangeable, surgeons who are new to MIGS have to move through a learning curve of five eyes to become safe but up to 30 eyes to become proficient even with active chamber management [11]. Viscoelastics are not recommended in plasma-mediated ablation because they can make visualization of the angle more difficult by trapping bubbles, debris, and blood and may cause carbonization of the ablation tip.…”

Section: Introductionmentioning

confidence: 99%

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Angle stability and outflow in dual blade ab interno trabeculectomy with active versus passive chamber management

et al. 2017

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PurposeTo compare intraoperative angle stability and postoperative outflow of two ab interno trabeculectomy devices that excise the trabecular meshwork with or without active aspiration and irrigation. We hypothesized that anterior segment optical coherence tomography (AS-OCT) allows for a quantitative comparison of intraoperative angle stability in a microincisional glaucoma surgery (MIGS) pig eye training model.MethodsTwelve freshly enucleated porcine eyes were measured with AS-OCT at baseline, at the beginning of the procedure and at its conclusion to determine the anterior chamber depth (ACD) and the nasal angle α in degrees. The right and left eye of pairs were randomly assigned to an active dual blade goniectome (aDBG) and a passive dual blade goniectome (pDBG) group, respectively. The aDBG had irrigation and aspiration ports while the pDBG required surgery under viscoelastic. We performed the procedures using our MIGS training system with a standard, motorized ophthalmic operating microscope. We estimated outflow by obtaining canalograms with fluorescent spheres.ResultsIn aDBG, the nasal angle remained wide open during the procedure at above 90° and did not change towards the end (100±10%, p = 0.9). In contrast, in pDBG, ACD decreased by 51±19% to 21% below baseline (p<0.01) while the angle progressively narrowed by 40±12% (p<0.001). Canalograms showed a similar extent of access to the outflow tract with the aDBG and the pDBG (p = 0.513). The average increase for the aDBG in the superonasal and inferonasal quadrants was between 27 to 31% and for the pDBG between 15 to 18%.ConclusionAS-OCT demonstrated that active irrigation and aspiration improved anterior chamber maintenance and ease of handling with the aDBG in this MIGS training model. The immediate postoperative outflow was equally good with both devices.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Angle stability and outflow in dual blade ab interno trabeculectomy with active versus passive chamber management

et al. 2017

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Intraocular pressure elevation precedes a phagocytosis decline in a model of pigmentary glaucoma

Dang

Waxman

Wang

et al. 2017

Preprint

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PurposeOutflow regulation and phagocytosis are key functions of the trabecular meshwork (TM), but it is not clear how the two are related in secondary open angle glaucomas characterized by an increased particle load. We hypothesized that diminished TM phagocytosis is not the primary cause of early ocular hypertension and recreated pigment dispersion in a porcine ex vivo model.Materials and MethodsSixteen porcine anterior chamber cultures received a continuous infusion of pigment granules (P), while 16 additional anterior chambers served as controls (C). Pressure transducers recorded the intraocular pressure (IOP). The phagocytic capacity of the trabecular meshwork was determined by fluorescent microspheres.ResultsThe baseline IOPs in P and C were similar (P=0.82). A significant IOP elevation occurred in P at 48, 120, and 180 hours (all P<0.01, compared to baseline). The pigment did not cause a reduction in TM phagocytosis at 48 hours, when the earliest IOP elevation occurred, but at 120 hours onward (P=0.001 compared to C). This reduction did not result in an additional IOP increase at 120 or 180 hours compared to the first IOP elevation at 48 hours (P>0.05).ConclusionIn this porcine model of pigmentary glaucoma, an IOP elevation occurs much earlier than when phagocytosis fails, suggesting that two separate mechanisms might be at work.

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Training strategies and outcomes of ab interno trabeculectomy with the trabectome

Fallano¹,

Bussel²,

Kagemann³

et al. 2017

F1000Res

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Plasma-mediated ab interno trabeculectomy with the trabectome was first approved by the US Food and Drug Administration in 2004 for use in adult and pediatric glaucomas. Since then, increased clinical experience and updated outcome data have led to its expanded use, including a range of glaucomas and angle presentations, previously deemed to be relatively contraindicated. The main benefits are a high degree of safety, ease, and speed compared to traditional filtering surgery and tube shunts. The increasing burden of glaucoma and expanding life expectancy has resulted in demand for well-trained surgeons. In this article, we discuss the results of trabectome surgery in standard and nonstandard indications. We present training strategies of the surgical technique that include a pig eye model, and visualization exercises that can be performed before and at the conclusion of standard cataract surgery in patients who do not have glaucoma. We detail the mechanism of enhancing the conventional outflow pathway and describe methods of visualization and function testing.

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Rapid learning curve assessment in an ex vivo training system for microincisional glaucoma surgery

Cited by 6 publications

References 1 publication

Angle stability and outflow in dual blade ab interno trabeculectomy with active versus passive chamber management

Angle stability and outflow in dual blade ab interno trabeculectomy with active versus passive chamber management

Intraocular pressure elevation precedes a phagocytosis decline in a model of pigmentary glaucoma

Training strategies and outcomes of ab interno trabeculectomy with the trabectome

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