Second-generation Trabecular Meshwork Bypass Stent (iStent inject ) Increases Outflow Facility in Cultured Human Anterior Segments

• Published in: American journal of ophthalmology 2012-06, Vol.153 (6), p.1206-1213
• Main Authors: Bahler, Cindy K, Hann, Cheryl R, Fjield, Todd, Haffner, David, Heitzmann, Hal, Fautsch, Michael P
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Anterior Eye Segment - metabolism; Aqueous Humor - secretion; Biological and medical sciences; Clinical trials; Diffusion Chambers, Culture; Female; Glaucoma; Humans; Imaging, Three-Dimensional; Male; Medical sciences; Microscopy, Electron, Scanning; Middle Aged; Miscellaneous; Ophthalmology; Organ Culture Techniques; Prospective Studies; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Stents; Therapy; Tissue Donors; Trabecular Meshwork - surgery; Trabecular Meshwork - ultrastructure
• ISSN: 0002-9394; 1879-1891
• DOI: 10.1016/j.ajo.2011.12.017

Purpose To determine whether a second-generation trabecular meshwork (TM) bypass stent (iStent inject ) influences outflow facility in cultured human anterior segments. Design Prospective laboratory investigation using normal human donor eyes. Methods Human anterior segments (n = 7) were placed in perfusion organ culture. One or 2 iStent inject stents were inserted into the TM within the nasal and/or superior quadrants using a specially designed injector. Anterior segments were returned to culture and perfused for an additional 24 hours. Morphology of the TM and Schlemm canal (SC) was assessed by scanning electron microscopy (SEM) and 3-dimensional micro-computed tomography (3D micro-CT). Results Insertion of 1 iStent inject into the nasal or superior quadrant of the TM increased outflow facility from 0.16 ± 0.05 μL/min/mm Hg to 0.38 ± 0.23 μL/min/mm Hg ( P < .03, n = 7), with concurrent pressure reduction from 16.7 ± 5.4 mm Hg to 8.6 ± 4.4 mm Hg. Addition of a second iStent inject further increased outflow facility to 0.78 ± 0.66 μL/min/mm Hg (n = 2). SEM showed the iStent inject flange compressed against the uveal region of the TM, the thorax securely inserted within the TM, and the head located in the lumen of SC. Dilation of SC was noted around the iStent inject head and SC cell disruption was observed at the iStent inject insertion site. 3D micro-CT confirmed iStent inject placement. Conclusion iStent inject , a second-generation bypass stent, increased outflow facility in human anterior segment culture. The iStent inject is a promising new device to lower intraocular pressure via TM bypass.