May 2004
Volume 45, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2004
Intraocular Pressure Changes During Extrusion in a Vitrectomized Cadaveric Eye
Author Affiliations & Notes
  • T.O. Thomas
    Ophthalmology, University of Texas at San Antonio Health Sciences Center, San Antonio, TX
  • A.S. Alurkar
    Ophthalmology, University of Texas at San Antonio Health Sciences Center, San Antonio, TX
  • J.C. Macdonald
    Ophthalmology, University of Texas at San Antonio Health Sciences Center, San Antonio, TX
  • Footnotes
    Commercial Relationships  T.O. Thomas, None; A.S. Alurkar, None; J.C. Macdonald, None.
  • Footnotes
    Support  Research to prevent blindness
Investigative Ophthalmology & Visual Science May 2004, Vol.45, 2008. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      T.O. Thomas, A.S. Alurkar, J.C. Macdonald; Intraocular Pressure Changes During Extrusion in a Vitrectomized Cadaveric Eye . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2008.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract

Abstract: : Purpose: During vitrectomy, the eye wall occasionally collapses into the midvitreous cavity while in aspiration mode. Resistance measurements and pressure curves were generated to determine why this occurs. Methods: A human cadaver eye was obtained from the eye bank. The intraocular pressure and pressures in the lines were measured with pressure transducers (BLPR, World Precision Instruments). All measured pressures were recorded with a MacLab data acquisition system connected to an Apple Macintosh computer. The Alcon Series Ten Thousand vitrectomy machine was used to perform a standard three port vitrectomy. Flows through the infusion line and extrusion line were measured by collecting and measuring the volumes of saline that flowed through them over two minutes. Using a simplification of Poiseuille's law, the resistances in the infusion and extrusion lines were then calculated by dividing the pressures across the lines by the flows through the lines. With the infusion pressure set to 30mmHg and the extrusion vacuum set to 250mmHg, intraocular pressure (IOP) was measured and graphed during active extrusion. Further trials were done with infusion pressure set at 50mmHg and 100mmHg with similar results as below. Results:. When no extrusion was used, there was good correlation between the programmed infusion pressure, the pressure in the infusion line exiting the machine, and the pressure measured in the eye. Resistance in the infusion line was 105 sec x mmHg/ml. Resistance in the extrusion line was found to be 1133 sec x mmHg/ml with the vitrectomy cutter on and 667 sec x mmHg/ml with the vitrectomy cutter off. During active extrusion, when the vitrectomy cutter was on, the steady state IOP was 15mmHg. With the vitrector in aspiration only mode, the IOP dropped to zero and the eye began collapsing after approximately three seconds Conclusions: We noted that the eye wall collapsed in aspiration only mode because of much lower outflow resistance compared with aspiration and vitrectomy together. When performing active extrusion, a surgeon should pay close attention to the eye wall and the infusion pressure to avoid having the eye wall collapse into the midvitreous cavity.

Keywords: intraocular pressure • vitreoretinal surgery • clinical (human) or epidemiologic studies: systems/equipment/techniques 
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×