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Geometry, penetration forces and cutting profile different of 23-gauge trocars systems

Session Details

Session Title: Vitreoretinal Surgery III

Session Date/Time: Friday 27/09/2013 | 11:00-12:30

Paper Time: 11:56

Venue: Hall 3 (Level 0)

First Author: C.Meyer SWITZERLAND

Co Author(s):    E. Rodrigues   Z. Liu   H. Kaymak        

Abstract Details


To investigate the geometry, penetration forces and cutting profile of 23-gauge trocars systems.


experimental study


11 commercially available 23-gauge trocar systems were analyzed according to the nomenclature ISO 7864 (DIN 13097) and ISO 9626: The outside diameters of the trocar (Da) and catheter {Da(cath)} were measured by Mitutoyo micrometer (S/N 8225 258). The point length (A), bevel length (C) primary bevel angle (α) and secondary bevel angle (γ)were measured under Olympus stereo-microscope SZH (S/N 509 130). Penetration force measurement with a fixed needle speed of 100 mm/min was performed on a Polyurethane Foil (PU 0.4mm) using the Penetrometer DEKA 9 (DKA 0108) and divided and separated into phases: 0 the maximum piercing force. F1 the maximum cutting resistance, F2 the maximum force from dilating the foil. FR the friction force which was hardly readable in these experiments. Fcath was the maximum force of the needle catheter/cannula.


The trocar needles were divided into 4 different designs: back bevel, spear bevel, lancet bevel and spatula bevel. The form of the catheter tip but also the length and form of the cut affect predominantly the penetration characteristics of the ‘catheter tip’ depended. The piercing forces (F0) of ‘back bevel’ and ‘spear’ pointed trocars were at the same level below 1N, while spatula systems and single bevel tips forming a round cutting required the highest penetration piercing force with 4.5 N. The Oertli lancet pointed needle had remarkable low piercing and cutting forces.


Our experimental model allowed us to compare the penetration forces of various trocars commercially available for vitrectomy in regard to incisional mechanical resistance. The earliest two-step 23-gauge system from Dutch Ophthalmic USA system promotes a linear incision with excellent wound architecture. All these improvements have been accomplished with better designed trocars, while the excellent wound closure and healing characteristics maintained.

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