Phaco Needle Design Parameter Effects: Factorial Design Modeling
Narrative Responses:
Purpose
Phaco needles transduce ultrasonic vibrations into mechanical energy as part of a tuned system. The needle design parameters such as hub length, shaft length, and wall thickness all influence needle performance. This study assesses the effect of varying these parameters on the tip displacement, stress and maximum energy input.
Methods
Using the Piezotran modelling software, four needle parameters were evaluated using a factorial design. We assessed the effect on tip excursion (microns), needle stress (milli-Pascals), and power input (Watts).
Results
Tip displacement varied from 34.5 to 67.3, stress from 100.9 to 158.5, power from 1.7 to 5.8. Parameter differences vary the displacement from as little as 3% to 33%, and power from 4% to 71%. Shaft length and wall thickness made the most difference.
Conclusion
Subtle changes in design parameters can almost double the tip excursion and increase the power nearly 3.5 times. Needle design is an important factor in improving phacoemulsification surgical efficiency.