Outflow Enhancement by Three Different ab Interno Trabeculectomy Procedures in a Porcine Anterior Segment Model

Abstract

Purpose: To evaluate three different microincisional ab interno trabeculectomy procedures in a porcine eye perfusion model. Methods: In perfused porcine anterior segments, 90 degrees of trabecular meshwork (TM) were ablated using the Trabectome (T; n = 8), Goniotome (G; n = 8), or Kahook device (K; n = 8). After 24 hours, additional 90 degrees of TM were removed. Intraocular pressure (IOP) and outflow facility were measured at 5 µL/min and 10 µL/min perfusion to simulate an elevated IOP. Structure and function were assessed with canalograms and histology. Results: 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 degrees 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. Conclusions: T, G and K significantly increased the outflow facility. In this model, T had a larger effect than G and K.

Comparison of a second-generation trabecular bypass (iStent inject) to ab interno trabeculectomy (Trabectome) by exact matching

“…The lowest IOP any TM bypass or ablation surgery could theoretically achieve is limited by the episcleral venous pressure of about 8 mmHg present in the episcleral venous veins [32]. This limit avoids an excessive pressure reduction that might cause hypotony as can happen after traditional glaucoma surgery [33] and after suprachoroidal [34] or subconjunctival MIGS [35].…”

Tissue-Engineered Anterior Segment Eye Cultures Display an Intraocular Pressure Homeostatic Response

“…Both increased age and decreased TM cellularity are major risk factors for the development of glaucoma. However, removal of meshwork tissue (both cells and ECM) is well-known to reduce IOP both ex vivo 27 and clinically [47][48][49] . Here, we show that the presence of decellularized TM ECM is associated with significant, sustained IOP elevation after a homeostatic challenge.…”

“…Unfortunately, human donor anterior segments are a limiting resource in outflow research. On the other hand, TM cells from donor globes, TM-removal surgeries, and TM cell lines, can be more often readily available 27,28 , lending themselves to more scalable studies.…”

Impact of freeze-thaw cytoablation on aqueous outflow patterns in ex vivo anterior chamber perfusion cultures and whole eyes

“…In contrast to human donor eyes, they are also ubiquitously available and remain responsive to stimuli and drugs when freshly harvested. This allows the exploration of anatomical functions 3,8 and the effects of biologicals 9 , drugs 10 , and surgical interventions 11 . Corresponding outflow changes can be studied with high spatial and temporal resolution 5,12,13 .…”