Optimization and comparison of a 0.7 mm tip with the 0.9 mm tip on an active-fluidics phacoemulsification platform.

PURPOSE: To assess the effect of varying levels of torsional power on phacoemulsification efficiency using an active-fluidics phacoemulsification platform with a 0.7 mm Sonata tip. SETTING: John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: A 0.7 mm tip was used to emulsify 2.0 mm porcine lenses that had been hardened in formalin. The torsional power was varied from 10% to 100% at intervals of 10%, and efficiency and chatter were recorded. A comparison of the 0.7 mm tip with the 0.9 mm Balanced tip was also performed. Using a torsional power setting of 90% and 100%, the 0.7 mm tip and the 0.9 mm tip efficiency times were recorded. RESULTS: The study showed an increase in efficiency as torsional power increased. The relationship was linear and more efficient up to 90% (R2 = .8025, P = .0005). Chatter was only observed at a torsional power setting of 60%. In addition, a head-to-head comparison of the 0.7 mm tip with the 0.9 mm tip showed that both tips were statistically similar in efficiency times, despite the smaller diameter of the 0.7 mm tip. CONCLUSIONS: The optimum torsional power setting with the Centurion platform in conjunction with the 0.7 mm tip was 90%. The efficiency of the 0.7 mm tip and the 0.9 mm tip was statistically similar.

Intraocular pressure study using monitored forced-infusion system phacoemulsification technology.

PURPOSE: To optimize phacoemulsification efficiency by varying the intraocular pressure (IOP) using the Centurion Vision System, a monitored forced-infusion system. SETTING: John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA. DESIGN: Laboratory investigation. METHODS: Porcine lenses were soaked in formalin and divided into 2.0 mm cubes; 0.9 mm balanced tips were used. Intraocular pressure levels were tested from 30 to 110 mm Hg at 10 mm Hg intervals. Vacuum was set at 500 mm Hg, aspiration at 35 mL/min, and torsional power at 60%. Efficiency (time to lens removal) and chatter (number of lens fragment repulsions from the tip) were measured. RESULTS: There was a linear relationship between efficiency and IOP. Increasing IOP led to an increase in efficiency (ie, to a decrease in time necessary to remove the lens fragment) (R(2) = .5769, P = .0176). Chatter correlated with IOP in the range of 30 to 50 mm Hg (R(2) = .4506, P = .0448) and was minimal at higher IOPs. CONCLUSIONS: Increasing IOP in the monitored forced-infusion system improved efficiency. Chatter was also decreased or eliminated with increasing IOP. Additional studies will be required to understand the reasons for these findings. FINANCIAL DISCLOSURE: None of the authors has a financial or proprietary interest in any material or method mentioned.

Comparison of Vacuum and Aspiration on Phacoemulsification Efficiency and Chatter Using a Monitored Forced Infusion System.

PURPOSE: To evaluate the effect of vacuum and aspiration rates on phacoemulsification efficiency and chatter using a monitored forced infusion system. DESIGN: In vitro animal study. SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah. PROCEDURES: Formalin-soaked porcine lenses were divided into 2 mm cubes (tip diameter, 0.9 mm). Vacuum levels were tested at 200, 300, 400, and 500 mm Hg; aspiration rates at 20, 35, and 50 mL/min. Torsional power was set at 60% and intraocular pressure at 50 mm Hg. RESULTS: Increasing vacuum increased efficiency regardless of aspiration rates (R(2) = 0.92; P = .0004). Increasing aspiration further increased efficiency when vacuum was at 400 and 500 mm Hg (P = .004 for 20 vs 35 mL/min, P = .0008 for 35 vs 50 mL/min). At 200 and 300 mm Hg, efficiency only improved when increasing aspiration to 35 mL/min (P < .0001 with 20 vs 35 + 50 mL/min). Chatter improved with increasing vacuum, up to 400 mm Hg (P = .003 for 200 vs 300 mm Hg and P = .045 for 300 vs 500 mm Hg). A similar trend of improved chatter was seen with increasing levels of aspiration. CONCLUSIONS: Vacuum improved efficiency up to 500 mm Hg independent of flow. Flow has an additive effect on efficiency through 50 mL/min, when vacuum is at 400 mm Hg or higher, and only up to 35 mL/min at vacuums less than 400 mm Hg. Chatter correlated with both vacuum and flow such that increasing either parameter decreases chatter, up to 400 mm Hg with vacuum.

Comparison of a torsional and a standard tip with a monitored forced infusion phacoemulsification system.

PURPOSE: To compare the relative efficiency and chatter of the 30-degree 0.9 mm Kelman tip (standard tip) and Ozil Intrepid Balanced tip (torsional tip) with identical optimum settings. SETTING: John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Porcine nuclei were fixed in formalin and cut into 2.0 mm cubes. Lens cubes were phacoemulsified with standard and torsional tips at 60% and 100% torsional amplitude with 0%, 25%, 50%, 75%, and 100% longitudinal power with monitored forced infusion. Experiments were performed at a constant vacuum, aspiration rate, and intraocular pressure. RESULTS: Linear regression showed increased efficiency with up to 75% longitudinal power at 60% torsional amplitude for both tips (P = .046 standard; P = .0093 torsional). Longitudinal did not significantly increase efficiency at 100% torsional power for either tip. Torsional tips were on average 29% more efficient than standard tips throughout the range tested (P < .0001), and 100% torsional power was on average 45% more efficient than 60% torsional power (P = .0028). Chatter was minimal except at 100% longitudinal power, which was greater than at 75% longitudinal power (P < .0001). At 100% longitudinal power, torsional tips had more chatter than standard tips (at 60% torsional, P < .0001; at 100% torsional, P = .0022). CONCLUSIONS: Increasing up to 75% longitudinal power increased the efficiency at 60% torsional for standard and torsional tips. Torsional tips were more efficient than standard tips. Chatter was generally minimal. Torsional tips showed more chatter than standard tips at 100% longitudinal power. FINANCIAL DISCLOSURE: None of the authors has a financial or proprietary interest in any material or method mentioned.

Torsional power study using CENTURION phacoemulsification technology.

BACKGROUND: To evaluate the effect of varying levels of power on phacoemulsification efficiency using the CENTURION Vision System. METHODS: Formalin-soaked porcine lenses were divided into 2-mm cubes; 0.9-mm, balanced tips were used. Torsional power levels were tested from 10% to 100% at 10% intervals. Vacuum was set to 550 mmHg, aspiration to 50 ml/min, and intraocular pressure at 50 mmHg. Efficiency (time to lens removal) and chatter (number of lens fragment repulsions from the tip) were determined. RESULTS: Increasing torsional power up to 60% increased efficiency. This effect was linear from 30 to 60% power (R2 = .90; P < 0.05). There were no significant differences in efficiency past 60%. Chatter was highest at 10% power and decreased linearly (R2 = .87; P = 0.007) as power was increased up to 60% power, and chatter did not improve above this power level. CONCLUSIONS: Power improved efficiency only up to a 60% power level, and then was negligible. Chatter correlated well with power up to the 60% level, so that as power was increased, chatter decreased. Because there are no additional benefits in efficiency past 60% power, and because chatter is minimal at 60% power, we recommend torsional ultrasound at 60% as the optimal power setting for using the CENTURION System for phacoemulsification.l.

Impact of micropulsed ultrasound power settings on the efficiency and chatter associated with lens-fragment removal.

PURPOSE: To determine the optimum power settings in micropulsed ultrasound (US). SETTING: John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Pig lenses hardened to be comparable to dense human cataracts were cut into 2.0 mm cubes and removed using micropulsed longitudinal US with previously optimized settings (6 milliseconds on and 6 milliseconds off and using a 0.9 mm 30-degree beveled bent phaco tip). The aspiration was set at 40 mL/min and the vacuum level at 550 mm Hg. Twenty lens cubes were tested with the power set from 10% to 100% in increments of 10%. Primary outcome measures were efficiency time (time to lens removal) and chatter (number of times the lens fragment visibly bounced off the tip). RESULTS: Efficiency time decreased with increasing power. There was a correlation between power and efficiency time (R(2) = 0.41, P = .046), which was more substantial between 30% and 100% power (R(2) = 0.71, P = .004). The mean number of chatter events did not differ significantly between power settings (R(2) = 0.012, P = .1195). CONCLUSIONS: There was a 5-fold increase in efficiency between 10% power and 20% power, which likely indicates that there is a minimum power threshold for efficient breakup of the lens. Between 20% and 100% power, there was a linear, strong, and statistically significant improvement in efficiency in these lens fragments. In addition, with micropulsed US there was little chatter or microchatter throughout the power range. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Determining optimal ultrasound off time with micropulse longitudinal phacoemulsification.

PURPOSE: To evaluate the optimum off time for the most efficient removal of lens fragments using micropulse ultrasound (US). SETTING: John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Porcine lens nuclei were soaked in formalin for 2 hours and then cut into 2.0 mm cubes using the Signature US machine with a bent 0.9 mm phaco tip with a 30-degree bevel. The on time was 7 milliseconds (ms), and the off time was varied from 2 to 20 ms in 2 ms steps. Phacoemulsification efficiency (time for fragment removal) and chatter (number of times the fragment bounced from the tip) were measured. RESULTS: A nonsignificant linear increase in efficiency was observed with 2 to 6 ms of off time (R(2) = .87, P = .24). A significant linear decrease in efficiency was observed with 6 to 20 ms (R(2) = .74, P = .006). CONCLUSIONS: With micropulse longitudinal US, 6 to 7 ms of off time was as efficient as shorter off times; longer off times (8 to 20 ms) showed decreased efficiency. Chatter was minimal and statistically similar throughout. To maximize phacoemulsification US efficiency, an off-time setting of 6 ms is recommended. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Optimum on-time duty cycle for micropulse technology.

PURPOSE: To evaluate the optimum on time for the most efficient removal of lens fragments using micropulsed ultrasound (US). SETTING: John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Twenty porcine lens nuclei were soaked in formalin for 2 hours and then divided into 2.0 mm cubes. Using an US machine with a 0.9 mm bent and a 30-degree bevel tip, the on time was varied every millisecond (ms) from 2 ms to 10 ms with the off time kept constant at 10 ms. Efficiency (time to lens removal) and chatter (number of lens fragment repulsions from the tip) were determined. RESULTS: The most efficient phacoemulsification was achieved with an on time of 6 ms. On times shorter than 6 ms were significantly less efficient (R2=.82, P=.04). Greater on times did not result in a significant difference in efficiency (R2=.03, P=.78) but did appear to have more chatter events when comparing 9 to 10 ms with 2 to 8 ms (P<.0001). CONCLUSIONS: With micropulsed longitudinal US, a 6 ms on time was equally as efficient as longer on times, while shorter on times (2 to 5 ms) had decreased efficiency. At 9 ms and 10 ms on time, significantly more chatter was noted. Therefore, to maximize phacoemulsification, an on-time setting of 6 ms is recommended. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Effect of phaco tip diameter on efficiency and chatter.

PURPOSE: To evaluate 3 phacoemulsification tips of different sizes and determine which size is most efficient in lens fragment removal using 3 ultrasound (US) approaches. SETTING: John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Porcine lens nuclei were formalin-soaked for 2 hours then divided into 2.0 mm cubes; 1.1 mm, 0.9 mm, and 0.7 mm phaco tips were used with torsional and micropulsed US. The 1.1 mm tips were unavailable for torsional US, so 0.9 mm and 0.7 mm tips were used. Efficiency (amount of time for lens removal) and chatter (number of lens-fragment repulsions from the tip) were determined. RESULTS: The mean phacoemulsification efficiency was highest with the 0.9 mm tip for all US variations. There were statistically significant differences between the 0.9 mm and 0.7 mm tips with micropulsed US (0.8 seconds ± 0.29 [SD] versus 1.4 ± 0.93 seconds; P=.0112) and transversal US (0.8 ± 0.17 seconds versus 1.4 ± 0.89 seconds; P=.0065). There was no significant difference between 0.9 mm and 0.7 mm tips with torsional US or between the 1.1 mm and 0.9 mm tips with micropulsed or transversal US; however, trends were identical, with 0.9 mm tips performing better than 0.7 mm and 1.1 mm tips. CONCLUSION: With all 3 systems, the 0.9 mm tip was most efficient, with the fewest outliers and smallest standard deviation. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Phacoemulsification efficiency with a radiused phaco tip.

PURPOSE: To evaluate radiused and nonradiused phacoemulsification tips to determine which tip is more efficient in removal of lens fragments using 3 ultrasound (US) modalities. SETTING: John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Porcine lens nuclei were formalin-soaked for 2 hours or 3 hours and then divided into 2.0 mm cubes. Thirty-degree, 0.9 mm beveled radiused tips and nonradiused tips were used with torsional, transverse, and micropulsed US modalities. Bent tips were used with torsional and transversal US, and straight tips were used with micropulsed US. Efficiency (time to lens removal) and chatter (number of lens fragment repulsions from the tip) were determined. RESULTS: The mean phacoemulsification efficiency was statistically significantly decreased (increased time for removal) with the radiused tip compared with the nonradiused tip for torsional US only (2-hour soaked lenses: 2.14 seconds ± 1.94 [SD] versus 1.18 ± 0.69 seconds [P < .05]; 3-hour soaked lenses: 5.07 ± 4.2 seconds versus 2.52 ± 1.99 seconds [P < .05]). There was no difference in chatter results. CONCLUSION: The radiused tip showed decreased efficiency with torsional US only. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Porcine lens nuclei as a model for comparison of 3 ultrasound modalities regarding efficiency and chatter.

PURPOSE: To validate a porcine lens model by comparing density and ultrasound (US) with known human standards using the Infiniti Ozil with Intelligent Phacoemulsification (torsional), Whitestar Signature Micropulse (longitudinal), and Ellips FX (transversal) modalities. SETTING: Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Lens nuclei were formalin soaked in hour-based intervals and divided into 2.0 mm cubes. Density was characterized by crushing experiments and compared with known human measures. Efficiency and chatter were examined. RESULTS: The mean weight to cut thickness in half ranged from 16.9 g ± 5.5 (SD) in the 0-hour group to 121.3 ± 47.5 gm in the 4-hour group. Lenses in the 2-hour group (mean 70.2 ± 19.1 g) best matched human density (P=.215). The mean efficiency ranged from 0.432 ± 0.178 seconds to 9.111 ± 2.925 seconds; chatter ranged from zero to 1.85 ± 1.927 bounces. No significant difference was detected when comparing the 2-hour formalin group with human lenses in torsional and transversal US. There was no significant difference between transversal and torsional modalities, consistent with human studies. Although longitudinal (6 milliseconds on, 12 milliseconds off) was significantly more efficient at 50% power than at 25%, there was no significant difference compared with transversal or torsional US. CONCLUSIONS: Animal lenses soaked for 2 hours in formalin were most comparable to human lenses. Longitudinal US may be an acceptable alternative to torsional and transversal US.

Objective comparison of 4 nonlongitudinal ultrasound modalities regarding efficiency and chatter.

PURPOSE: To compare efficiency and chatter of Infiniti Ozil with and without Intelligent Phacoemulsification (IP) and the Signature Ellips with and without FX. SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Brunescent 2.0 mm human lens cubes were created by an instrument devised for this study. Cubes were tested (10 per test) for time of particle removal (efficiency) and for the number of times the lens particle bounced off the tip (chatter) at 300 mm Hg and 550 mm Hg, 50% and 100% power, and 50% and 100% amplitudes (amplitude for Ozil only). RESULTS: Of the ultrasound settings, efficiency varied from a mean of 3.3 seconds ± 1.4 (SD) to 50.4 ± 11.7 seconds and chatter from 0.0 to 52.0 ± 16.7 bounces per run. The Ozil-IP was generally more efficient than the Ozil and the Ellips FX more efficient than the Ellips. At optimized values, the Ozil-IP and Ellips-FX were similar. In general, efficiency and chatter were better at 550 mm Hg and at 50% power. The amplitude effect was complex. Efficiency closely correlated with chatter (Pearson r(2) = .31, P<.0001). CONCLUSIONS: Objective comparison of phacoemulsification efficiency and chatter found that optimized Ozil-IP and Ellips-FX were similar in both parameters and in general, both performed better than preceding technology. The study parameters can significantly affect efficiency and chatter, which strongly correlate with each other.