Flow Dynamics of Extrusion Needle Vacuuming in a Closed Vitrectomy System

Ronald P. Danis, John T. Thompson

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


The dynamics of pressure, flow, and ocular volume relationships were examined with respect to extrusion needle use in simulated vitrectomy. Glass-stoppered bottles used with infusion lines with drip chambers lowered the intraocular pressure 4 to 7 inches below the fluid level in the bottle, varying with the amount of fluid in the bottle. Compared with flow rates using the regular tip needle with the steel infusion cannula, the disposable infusion cannula lowered the flow rate by about 25% and the tapered tip extrusion needle decreased outflow by 40% to 50%. Tracer dilution rates were decreased by the use of the disposable infusion port or the aphakic model eye; however, 2 minutes of infusion at a 30-inch bottle height dilution was still sufficient to wash out the tracer to less than 5% of the original concentration.

Original languageEnglish (US)
Pages (from-to)267-270
Number of pages4
JournalArchives of ophthalmology
Issue number2
StatePublished - Feb 1990

ASJC Scopus subject areas

  • Ophthalmology


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