Purchase this article with an account.
D.S. Minckler, B.A. Francis, R.F. See, N.A. Rao, G. Baerveldt; Histopathology of Trabectome . Invest. Ophthalmol. Vis. Sci. 2006;47(13):31.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To design an instrument capable of removing trabecular meshwork and inner wall of Schlemm's canal via a minimally invasive ab interno approach, without damage to adjacent structures.
A micro–electrocautery (550 KHz) unit shielded by a curved footplate sized to fit into Schlemm's canal has been incorporated in a 19.5 gauge infusion and aspiration handpiece. The footplate is pointed to permit insertion into Schlemm's canal through the meshwork via an ab interno approach and coated with several layers of smooth ceramic material as insulation. Cautery–ablation is performed by moving the tip along the canal with the footplate acting as a guide. Twenty human corneal donor rings stabilized in a holding device were subjected to varying arcs of ablation under microscopic control while immersed in balanced salt utilizing a prototype handpiece and a range of power settings (0.3–5.0 Watts). Tissues were then studied with light and confocal microscopy to ascertain whether or not heat or mechanical injury to structures adjacent to Schlemm's had occurred. Two control specimens were subjected to simulated goniotomy. During clinical use under gonioscopic control, the Trabectome handpiece utilizes continual infusion and aspiration to stabilize the anterior chamber and provide cooling and debris removal.
Histopathology studies of human corneal donor rings subjected to electro–cautery ablation revealed relatively clean removal of a strip of trabecular meshwork and inner wall of the canal with minimal detectable mechanical or heat injury to the back wall of Schlemm's or adjacent cornea or sclera. Injury was defined by a range of 1+ (minimal) to 4+ (maximal) light microscopy features including increased eosinophilic staining, trabecular beam retraction or increased tortuosity of trabecular beams. The mean separation of residual trabecular beams was measured (µm) and generally increased as the power utilized increased. Control goniotomy specimens (n = 2) by contrast with confocal examination demonstrated disruption of the meshwork and incisional injury to adjacent sclera.
The Trabectome system offers an ab interno method of opening an arc of Schlemm's canal to direct aqueous access with minimal histological evidence of damage to adjacent tissues.
This PDF is available to Subscribers Only