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Vitreous flow rates through dual pneumatic cutters: effects of duty cycle and cut rate

Authors Abulon DJK

Received 19 July 2014

Accepted for publication 9 September 2014

Published 5 February 2015 Volume 2015:9 Pages 253—261

DOI https://doi.org/10.2147/OPTH.S71387

Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 3

Editor who approved publication: Dr Scott Fraser


Dina Joy K Abulon

Medical Affairs, Alcon Research, Ltd, Lake Forest, CA, USA

Purpose: We aimed to investigate effects of instrument settings on porcine vitreous flow rates through dual pneumatic high-speed vitrectomy probes.
Methods: The CONSTELLATION® Vision System was tested with 250, 450, and 650 mmHg of vacuum using six ULTRAVIT® vitrectomy probes of each diameter (25+®, 25, 23, and 20 gauge) operated from 500 cuts per minute (cpm) up to 5,000 cpm. Duty cycle modes tested included biased open, 50/50, and biased closed. Flow rates were calculated by assessing the change in weight of porcine eyes during vitreous aspiration. Volumetric flow rate was measured with a computer-connected electronic scale.
Results: At lower cut rates, the biased open mode produced higher flow than did the 50/50 mode, which produced higher flow than did the biased closed mode. In the biased closed and 50/50 modes, vitreous flow rates tended to increase with increasing cut rate. Vitreous flow rates in the biased open duty cycle mode remained relatively constant across cut rates.
Conclusion: Vitreous flow rates through dual pneumatic vitrectomy probes could be manipulated by changing the duty cycle modes on the vitrectomy system. Differences in duty cycle behavior suggest that high-speed cut rates of 5,000 cpm may optimize vitreous aspiration.

Keywords: enhanced 25-gauge vitrectomy, 25-gauge vitrectomy, 20-gauge vitrectomy, 23-gauge vitrectomy, aspiration, Constellation Vision System


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