Control of Intraocular Pressure During Phacoemulsification

A method of operating a phacoemulsification device, comprising:

• providing a surgical system comprising a pump and a handpiece, wherein the handpiece comprises an irrigation channel, a needle and a sleeve coaxially surrounding at least a portion of the needle, wherein the irrigation channel is fluidly coupled with the sleeve, and wherein the sleeve comprises a cross-sectional flow area between an outer surface of the needle and the inner surface of the sleeve that is smaller than a cross-sectional area of the irrigation channel;
• receiving a first pressure measurement signal indicative of pressure at a first location in said irrigation channel and a second pressure measurement signal indicative of pressure at a second location in said irrigation channel;
• identifying pressure fluctuations occurring at one or both said first pressure measurement signal and said second pressure measurement signal;
• comparing said first pressure measurement signal and said second pressure measurement signal, for said pressure fluctuations, to provide one or more frequency dispersion indicators indicative of frequency dispersion between said first pressure measurement signal and said second pressure measurement signal;
• characterizing said pressure fluctuations as associated with intraocular pressure (IOP) or as associated with system pressure, based on said one or more frequency dispersion indicators;
• and
• for a pressure fluctuation associated with IOP:
• determining an estimate of IOP from said first pressure measurement signal;
• and
• controlling said pump based on said estimate of IOP.