We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
Thiel cadaver eye as a training model for sub-Tenon's blocks: a feasibility study.
- Authors
Lersch, Friedrich; Schnidrig, Damian; Boemke, Susanne; Djonov, Valentin; Jaggi, Damian; Heussen, Florian M.
- Abstract
Background: Regional anaesthesia education, especially for ocular procedures, necessitates reliable surgical training models. While cadaveric models offer anatomical fidelity, conventional embalming methods may compromise tissue integrity. We aimed to assess the effectiveness of Thiel cadavers for training in sub-Tenon's blocks by evaluating ocular tissues and measuring insertion forces. Methods: Experimental design, using twenty eyes from ten Thiel cadaver heads. These cadavers were specifically prepared to test the administration of sub-Tenon's blocks. The research was conducted in a controlled laboratory setting appropriate for handling cadaveric materials and conducting precise measurements. Each cadaver eye underwent an initial ultrasound examination, and its axial length was noted. An intravitreal injection of heptastarch solution followed, to re-establish the eye's sphericity. After this volume injection, the axial length and intraocular pressure were measured again. Mock sub-Tenon's blocks were administered in 2 separate quadrants of the eye, with insertion forces measured using a pressure gauge. These were compared to a data set of insertion forces measured in a series of isolated pig's eyes on which STBs had been performed. Main outcome measurements were macroscopic assessment of the ocular tissue layers and the insertion forces required for the sub-Tenon's blocks. In a second set of 10 Thiel cadaver heads, 5 ml of sodium chloride were injected as sub-Tenon's blocks and the emergence of a periocular "T-sign" ascertained and measured by ultrasound. Results: Four of twenty eyes (20%) retained near-natural sphericity, with the remaining requiring volume injection to approximate physiological shape and pressure. The conjunctiva and Tenon's layer were intact, and correct cannula placement was achieved in all cases. In 16 of 20 eyes where T-signs could be measured, the median thickness of the T-sign amounted to 2.72 mm (range 1.34 mm–5.28 mm). The average maximum cannula insertion force was 2.92 Newtons. Insertion forces in intact Thiel cadaver heads were consistently higher than in isolated pig's eyes (3.6 N vs 2.0 N). Conclusion: These findings suggest that Thiel cadavers are a promising model for training in sub-Tenon'sblocks, despite the challenge of often desiccated and involuted eyes. Key points: • Thiel cadaver eyes were evaluated as training model for sub-Tenon's blocks for the first time • The cadaver eyes were often involuted and required fluid injection to reproduce physiological bulbar tonus • The ocular tissues and anatomical layers were well preserved • T-signs as a hallmark of successful sub-Tenon's block can be ascertained in Thiel cadaver eyes • Dynamic insertion forces were measured during cannula placement and can be used as reference for future studies comparing haptics of different models by an objective measure-insertion force.
- Subjects
FLUID injection; INTRAVITREAL injections; HUMAN anatomical models; MATERIALS handling; INTRAOCULAR pressure
- Publication
BMC Ophthalmology, 2024, Vol 24, Issue 1, p1
- ISSN
1471-2415
- Publication type
Article
- DOI
10.1186/s12886-024-03630-3