Outflow enhancement by three different ab interno trabeculectomy procedures in a porcine anterior segment model

  • Yalong Dang
  • Chao Wang
  • Priyal Shah
  • Susannah Waxman
  • Ralitsa T. Loewen
  • Ying Hong
  • Hamed Esfandiari
  • Nils A. LoewenEmail author
Basic Science



To evaluate three different microincisional ab interno trabeculectomy procedures in a porcine eye perfusion model.


In perfused porcine anterior segments, 90° of trabecular meshwork (TM) was ablated using the Trabectome (T; n = 8), Goniotome (G; n = 8), or Kahook device (K; n = 8). After 24 h, additional 90° of TM was removed. Intraocular pressure (IOP) and outflow facility were measured at 5 and 10 μl/min perfusion to simulate an elevated IOP. Structure and function were assessed with canalograms and histology.


At 5 μl/min infusion rate, T resulted in a greater IOP reduction than G or K from baseline (76.12% decrease versus 48.19% and 47.96%, P = 0.013). IOP reduction between G and K was similar (P = 0.420). Removing another 90° of TM caused an additional IOP reduction only in T and G but not in K. Similarly, T resulted in the largest increase in outflow facility at 5 μl/min compared with G and K (first ablation, 3.41 times increase versus 1.95 and 1.87; second ablation, 4.60 versus 2.50 and 1.74) with similar results at 10 μl/min (first ablation, 3.28 versus 2.29 and 1.90 (P = 0.001); second ablation, 4.10 versus 3.01 and 2.01 (P = 0.001)). Canalograms indicated circumferential flow beyond the ablation endpoints.


T, G, and K significantly increased the outflow facility. In this model, T had a larger effect than G and K.


Ab interno trabeculectomy Intraocular pressure Outflow facility Canalogram Trabecular meshwork 



This study was funded by the Wiegand Fellowship of the Eye and Ear Foundation of Pittsburgh (YD), by the Initiative to Cure Glaucoma of the Eye and Ear Foundation of Pittsburgh (NAL), by an NIH CORE Grant P30 EY08098 to the Department of Ophthalmology, and an unrestricted grant from Research to Prevent Blindness, New York, NY.

Compliance with ethical standards

Conflict of interest

Author NAL has received speaker honoraria for lectures and wetlabs from Neomedix Corp.

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors. No animals were sacrificed for the purpose of doing research. An approval by an ethics committee or institutional animal care and use committee was not required.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Yalong Dang
    • 1
  • Chao Wang
    • 1
    • 2
  • Priyal Shah
    • 1
    • 3
  • Susannah Waxman
    • 1
  • Ralitsa T. Loewen
    • 1
  • Ying Hong
    • 1
  • Hamed Esfandiari
    • 1
  • Nils A. Loewen
    • 1
    Email author
  1. 1.Department of OphthalmologyUniversity of Pittsburgh School of MedicinePittsburghUSA
  2. 2.Department of Ophthalmology, Xiangya HospitalCentral South UniversityChangshaPeople’s Republic of China
  3. 3.Institute of Ophthalmology and Visual ScienceRutgers New Jersey Medical SchoolNewarkUSA

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