Electronically detecting phacoemulsification tip engagement with a lens

Abstract

A system and method include vibrating a needle of a phacoemulsification handpiece by driving one or more piezoelectric crystals in the handpiece with one or more electrical signals having different respective frequencies using one or more respective drive modules. The needle is inserted into an eye of a patient. The frequencies of the electrical signals are tuned to respective one or more target frequencies, and respective electrical impedances seen by the drive modules are registered. In response to an electrical impedance seen by at least one of the drive modules undergoing a change exceeding a preset impedance change, an indication is provided that material in the eye surrounding the needle has changed, a level of vibration of the needle is changed, and/or the frequency of at least one of the drive modules is adjusted to an electrical resonant frequency thereof.

1 . A method, comprising:
 vibrating a needle of a phacoemulsification handpiece by driving one or more piezoelectric crystals in the handpiece with one or more electrical signals having different respective frequencies using one or more respective drive modules;   inserting the needle into an eye of a patient;   tuning the frequencies of the electrical signals to respective one or more target frequencies, and registering respective electrical impedances seen by the drive modules; and   in response to an electrical impedance seen by at least one of the drive modules undergoing a change exceeding a preset impedance change, providing an indication that material in the eye surrounding the needle has changed.   
     
     
         2 . The method according to  claim 1 , further comprising, in response to an electrical impedance seen by at least one of the drive modules undergoing a change, changing a level of vibration of the needle. 
     
     
         3 . The method according to  claim 1 , wherein tuning the one or more frequencies comprises setting the target frequencies to be respective resonance frequencies of the one or more piezoelectric crystals as measured by the drive modules. 
     
     
         4 . The method according to  claim 3 , wherein tuning the frequencies comprises setting the target frequencies to be respective resonance frequencies of the one or more piezoelectric crystals as measured by the drive modules, so as to differentiate between the needle engaging with the lens, and the needle disengaging from the lens. 
     
     
         5 . The method according to  claim 1 , wherein the change in the impedance is in response to one of the needle engaging with a lens of the eye, and the needle disengaging from the lens of the eye. 
     
     
         6 . The method according to  claim 1 , further comprising, in response to the change in the electrical impedance exceeding the preset impedance change, adjusting a frequency of at least one of the drive modules to comprise an electrical resonant frequency thereof. 
     
     
         7 . The method according to  claim 1 , wherein tuning the frequencies of the electrical signals to respective one or more target frequencies comprises detuning one or more of the frequencies off-resonance, in order to have an inverse change in electrical impedance magnitude with a decreased versus an increased mechanical load on the needle. 
     
     
         8 . The method according to  claim 1 , wherein providing an indication comprises providing one of an audio and visual indication. 
     
     
         9 . The method according to  claim 1 , wherein providing an indication comprises providing vibratory indication. 
     
     
         10 . A system, comprising:
 a phacoemulsification handpiece comprising a needle configured to be inserted into an eye of a patient and be vibrated by driving one or more piezoelectric crystals in the handpiece with one or more electrical signals having different respective frequencies using one or more respective drive modules; and   a processor, which is configured to: 
 tune the frequencies of the electrical signals to respective one or more target frequencies, and register respective electrical impedances seen by the drive modules; and 
 in response to an electrical impedance seen by at least one of the drive modules undergoing a change exceeding a preset impedance change, provide an indication that material in the eye surrounding the needle has changed. 
   
     
     
         11 . The system according to  claim 10 , wherein the processor is further configured to, in response to an electrical impedance seen by at least one of the drive modules undergoing a change, change a level of vibration of the needle. 
     
     
         12 . The system according to  claim 10 , wherein the processor is configured to tune the one or more frequencies by setting the target frequencies to be respective resonance frequencies of the one or more piezoelectric crystals as measured by the drive modules. 
     
     
         13 . The system according to  claim 12 , wherein tuning the frequencies comprises setting the target frequencies to be respective resonance frequencies of the one or more piezoelectric crystals as measured by the drive modules, so as to differentiate between the needle engaging with the material, and the needle disengaging from the material. 
     
     
         14 . The system according to  claim 13 , wherein the material is lens material. 
     
     
         15 . The system according to  claim 10 , wherein the change in the impedance is in response to one of the needle engaging with the material of the eye, and the needle disengaging from the material of the eye. 
     
     
         16 . The system according to  claim 10 , wherein the processor is further configured to, in response to the change in the electrical impedance exceeding the preset impedance change, adjust the frequency of at least one of the drive modules to comprise an electrical resonant frequency thereof. 
     
     
         17 . The system according to  claim 10 , wherein the processor is configured to tune the frequencies of the electrical signals to respective one or more target frequencies by detuning one or more of the frequencies off-resonance, in order to have an inverse change in electrical impedance magnitude with a decreased versus an increased mechanical load on the needle. 
     
     
         18 . The system according to  claim 10 , wherein the processor is configured to provide an indication by providing one of an audio and visual indication. 
     
     
         19 . The system according to  claim 10 , wherein the processor is configured to provide an indication by providing vibratory indication. 
     
     
         20 . The system according to  claim 10 , wherein the material is lens material. 
     
     
         21 . A method, comprising:
 vibrating a needle of a phacoemulsification handpiece by driving one or more piezoelectric crystals in the handpiece with one or more electrical signals having different respective frequencies using one or more respective drive modules;   inserting the needle into an eye of a patient;   tuning the frequencies of the electrical signals to respective one or more target frequencies, and registering respective electrical impedances seen by the drive modules; and   in response to an electrical impedance seen by at least one of the drive modules undergoing a change exceeding a preset impedance change, changing a level of vibration of the needle or adjusting the frequency of at least one of the drive modules to comprise an electrical resonant frequency thereof.   
     
     
         22 . A system, comprising:
 a phacoemulsification handpiece comprising a needle configured to be inserted into an eye of a patient and be vibrated by driving one or more piezoelectric crystals in the handpiece with one or more electrical signals having different respective frequencies using one or more respective drive modules; and   a processor, which is configured to: 
 tune the frequencies of the electrical signals to respective one or more target frequencies, and register respective electrical impedances seen by the drive modules; and 
 in response to an electrical impedance seen by at least one of the drive modules undergoing a change exceeding a preset impedance change, change a level of vibration of the needle or adjust the frequency of at least one of the drive modules to comprise an electrical resonant frequency thereof.