Hydrodynamic analysis of intraocular pressure changes during anterior chamber procedures.

Variations in intraocular pressure (IOP), observed by us and other authors in closed-system anterior chamber procedures, are explained using a simple hydrodynamic analysis based on the Bernoulli equation. Calculations show that the sudden increases in IOP (pressure spikes) measured during anterior segment surgery are due primarily to the small size of the infusion cannulas and are exacerbated by high infusion rates. Accurate measurement of these IOP variations requires placement of the pressure sensors in situ and is not possible by remote pressure sensing at the infusion line or the console. This work indicates that closed-system procedures could benefit from accurate monitoring of intraoperative IOP and could use these measurements for automatic IOP control during surgery.