Intraocular pressure control

A method of controlling intraocular pressure with a microsurgical system, comprising the steps of:

• providing a desired intraocular pressure;
• storing a known volume of a pressurized gas in a receiver;
• providing a pressure transducer for measuring the pressure of said gas in said receiver;
• using said gas to pressurize a surgical fluid stored in an infusion chamber of an ophthalmic surgical cassette, said cassette having a fluid level sensor for measuring the level of said fluid in said infusion chamber;
• calculating an expected pressure decay in said receiver with a computer using said measured level of said fluid;
• calculating a volume flow rate of said fluid with said computer using said expected pressure decay;
• calculating an expected intraocular pressure with said computer using said volume flow rate and said measured pressure of said gas;
• and
• adjusting said amount of said gas in said using step with said computer based on a comparison of said expected intraocular pressure and said desired intraocular pressure.