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Feedback control device controlling phaco tip elongation

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First Author: T.Rossi ITALY

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Abstract Details


To assess whether the use of a novel feedback device intended to control phacoemulsification tip elongation is effective under varying machine settings and material resistance.


In vitreo study on agar gel of increasing density.


Phacoemulsification was simulted by using typical surgical settings on increasingly dense agar gel. Sculpt mode phaco (550 mmHg Venturi pump; elongation 35 and 70 µm) and quadrant settings (550 mmHg Venturi pump; elongation 15, 30 and 60 µm) were used in agar gel of incremental density (1%, 2%, 3% and 6% in demineralised water). Dispersed lens fragments were also simulated with 6% agar gel spherules (2-5 mm in diameter; 550 mmHg vacuum and 60 µm elongation). Actual phaco tip elongation measured on voltage readings from the piezoelectric crystals and compared to nominal elongation with feedback control off and on.


Mismatch between nominal and actual elongation with control off varied between -13.51 µm and –23.07 µm of nominal elongation in sculpt and between -2.79 µm and -20.41 µm in quadrant mode. With control on, mismatch varied between -0.02 µm and +0.43 µm (p<0.001 for all). With system off the elongation mismatch between 1%, 3% and 6% agar was also statistically significant (p<0.001). Elongation was 44.72±4.16 µm with control off and 60.02±1.63 µm on (nominal elongation 60 µm; p<0.001), when emulsifying agar 6% gel fragments. Dispersion of elongation data was also significantly wider with control off.


Tested feedback control system effectively controls elongation accuracy regardless to resistance offered by incremental agar gel concentrations.

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