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C. Lewis, W. Dupps, J. Perry, G. Kosmorsky; Flow Resistance of Pyrex Jones Tube and Novel Silicone Jones Tube. Invest. Ophthalmol. Vis. Sci. 2008;49(13):2296. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
A novel silicone Jones tube was designed by one of us (GK) to address the shortcomings of the traditional pyrex Jones tube, including difficult placement due to varying patient anatomy and occasional extrusion requiring surgical repositioning. The silicone Jones tube is a one-size-fits-all design that is easily cut to an appropriate length at the time of surgery, and it has cut-back ridges that are designed to reduce extrusion. The ability of the Jones tube to conduct tears is directly related to the flow resistance of the device. The purpose of this study is to compare the flow resistance of a traditional pyrex Jones tubes to the silicone Jones tube cut to various lengths.
A syringe pump delivered a constant flow rate of saline through the Jones tubes. We measured the steady state irrigation pressure using an in-line transducer and digital pressure monitor. We obtained five measurements under each of six conditions: a 17 mm pyrex Jones tube, a silicone Jones tube cut to four different lengths (37 mm, 25 mm, 17 mm, and 13 mm), and a control condition with no tube attached. Resistance was calculated from the flow rate and pressure measurements.
The syringe pump delivered saline at 1 cc/s. The average pressure using the 17 mm pyrex Jones tube was 7 +/- 0 mmHg. The calculated resistance was 7 mmHg x sec/ml. For the silicone Jones tube, the average pressure/resistance for the various tube lengths was: 37 mm tube, 4 +/- 0 mmHg/4 mmHg x sec/mL; 25 mm tube, 3.8 +/- 0.4 mmHg/3.8 mmHg x sec/ml; 17 mm tube, 4 +/- 0 mmHg/4 mmHg x sec/ml; 13 mm tube, 2.6 +/- 0.5 mmHg/2.6 mmHg x sec/ml. The average pressure with no tube attached was 1 +/- 0 mmHg and the calculated resistance was 1 mmHg x sec/ml.
For each of the four lengths of the novel silicone Jones tube (37 mm, 25 mm, 17 mm, and 13 mm), the flow resistance was lower than that of the 17 mm pyrex Jones tube. The lower flow resistance of the silicone Jones tube may better facilitate tear drainage. The silicone tube, however, may be more susceptible to compressive forces in situ compared with the rigid pyrex tube. Further studies, including human clinical trials, are needed to assess the clinical efficacy of the silicone Jones tube.
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