April 1997
Volume 38, Issue 5
Free
Articles  |   April 1997
The mechanism of intraocular pressure rise during cyclocryotherapy.
Author Affiliations
  • O Geyer
    Department of Ophthalmology, Sourasky Medical Center, Tel-Aviv University, Israel.
  • A Michaeli-Cohen
    Department of Ophthalmology, Sourasky Medical Center, Tel-Aviv University, Israel.
  • D M Silver
    Department of Ophthalmology, Sourasky Medical Center, Tel-Aviv University, Israel.
  • M Neudorfer
    Department of Ophthalmology, Sourasky Medical Center, Tel-Aviv University, Israel.
  • M Lazar
    Department of Ophthalmology, Sourasky Medical Center, Tel-Aviv University, Israel.
Investigative Ophthalmology & Visual Science April 1997, Vol.38, 1012-1017. doi:
  • Views
  • PDF
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      O Geyer, A Michaeli-Cohen, D M Silver, M Neudorfer, M Lazar; The mechanism of intraocular pressure rise during cyclocryotherapy.. Invest. Ophthalmol. Vis. Sci. 1997;38(5):1012-1017.

      Download citation file:


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

      ×
  • Supplements
Abstract

PURPOSE: Intraocular pressure (IOP) spikes that occur during cyclocryotherapy for advanced glaucoma may further injure the already damaged glaucomatous optic nerve and be responsible for visual impairment that may occur after this treatment. The authors investigated the mechanism of pressure rise to see whether it can be avoided and thus prevent further optic nerve injury. The authors postulated that intraocular ice forms during the cryo procedure and causes the pressure changes. METHODS: Intraocular pressure was monitored using a pneumatonometer during 15 cryocycles of four patients with advanced glaucoma and 21 cryocycles of five normal rabbits. A simple thermal model was developed to analyze the relation between volume expansion and pressure rise in the eye. The physical effect of freezing rabbit eye structures was investigated in vitro. RESULTS: The largest pressure spikes observed during the cryocycles in this work were increases of 32 mm Hg for humans and 25 mm Hg for rabbits. The mean value of the IOP immediately before and after the cryo freezing stage was 53 +/- 1 and 68 +/- 2 mm Hg, respectively, for humans and 22 +/- 1 and 32 +/- 1 mm Hg for rabbits. The parameters of the thermal model were determined from the observed IOP spikes. Calculated thaw times were consistent with measured times for return to precryo IOPs. In vitro cryoapplication (rabbit eye) showed the formation of an ice ball internal to the eye. CONCLUSIONS: Volumetric increase of the intraocular content related to the formation of an ice ball in the eye, is the mechanism of pressure spikes during cyclocryotherapy. Because this complication is unavoidable, other cyclodestuctive methods may be more prudent, particularly in patients with advanced glaucoma.

×
×

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.

×