Thermal comparison of Infiniti OZil and Signature Ellips phacoemulsification systems

Optimum on-time and off-time combinations for micropulse phacoemulsification in venturi vacuum mode

PURPOSE

To measure the time to fragment removal and number of chatter events using various combinations of micropulse on times and off times (measured in milliseconds) of longitudinal ultrasound (US) using a venturi-based phacoemulsification system.

SETTING

John A. Moran Eye Center, University of Utah, Salt Lake City, USA.

DESIGN

Experimental study.

METHODS

Pig lenses were hardened with formalin and cut into 2.0 mm cubes. The time to fragment removal (efficiency) and frequency of fragments bouncing off the tip (chatter) were measured with the venturi-based system. Micropulse longitudinal US was tested. Parameters were combinations of 5, 6, and 7 milliseconds on, with 5, 6, and 7 milliseconds off. Twenty runs each of 9 combinations were completed.

RESULTS

There was a statistically significant difference between on/off duty cycle combinations. The 6 on/7 off group had higher efficiency than the 5 on/6 off and 7 on/7 off groups. Six on/5 off was more efficient than 5 on/6 off. When data were pooled and on times alone were used, 6 milliseconds on time was more efficient than 5 or 7 milliseconds. No efficiency differences in off times were found. No significant chatter differences were observed.

CONCLUSIONS

Using micropulse longitudinal US in venturi vacuum mode, 6 milliseconds on was the most efficient on time. Five, 6, and 7 milliseconds off times had similar efficiency. These data suggest that the most efficient setting with lowest US energy use is 6 milliseconds on and 7 milliseconds off.

Wound and surface temperatures in vivo in torsional and longitudinal modalities of ultrasound in coaxial microincisional cataract surgery

BACKGROUND

To study phacoemulsification probe shaft/wound and corneal surface/tip temperatures in vivo during longitudinal, torsional and combined phacoemulsification modes and their relationship to machine parameters.

DESIGN

This was a prospective study at Chaithanya Eye Hospital and Research Institute, Trivandrum, India (tertiary).

PARTICIPANTS

Twenty-two eyes of 22 patients were randomized into six groups depending on the grade of nuclear sclerosis (NS) and the type of ultrasound used: Group 1, torsional in NS2; Group 2, torsional in NS3; Group 3, torsional with intermittent longitudinal in NS2; Group 4, torsional with intermittent longitudinal in NS3; Group 5, longitudinal in NS2; Group 6, longitudinal in NS3.

METHODS

Patients underwent phacoemulsification by torsional, longitudinal or combined modalities. A thermal camera was used to measure phaco probe temperatures.

MAIN OUTCOME MEASURES

The mean probe shaft and tip temperatures were documented for different ultrasound modalities.

RESULTS

The mean shaft and tip temperatures were: Group 1, 29.22°C±0.71°C and 28.4°C±0.88°C; Group 2, 32.12°C±0.62°C and 31.88°C±0.84°C; Group 3, 30.25°C±0.71°C and 29.35°C±0.62°C; Group 4, 31.95°C±0.65°C and 32.01°C±1.31°C; Group 5, 23°C and 27.6°C and Group 6, 23°C and 29.68°C, respectively. In all groups using longitudinal ultrasound, the phaco tip surface temperatures were higher than the shaft temperatures, except in Group 3. Shaft temperatures were higher than tip temperatures in cases using torsional phaco, except in Group 4. The mean temperature difference between groups was significant only for shaft temperatures (P=0.001). On thermal imaging, for torsional phaco, the rise in temperature of the probe from shaft to tip was dependent on the amplitude of ultrasound applied (P=0.009).

CONCLUSION

The shaft temperatures were higher than over the phaco tip during torsional phacoemulsification.

Thermal evaluation of two phacoemulsification systems

OBJECTIVE

To compare thermal profiles of new transversal ultrasound power modulation to torsional ultrasound in an artificial chamber and cadaver eye.

DESIGN

Laboratory investigation.

METHODS

John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, was the study setting. Temperature increase after 30 seconds was measured at the needle midshaft in an artificial chamber and at maximal friction point in a cadaver eye. Ellips FX (transverse) was tested at 100% power, as was Signature with micropulse settings (6 milliseconds on and off). OZil (torsional only) was tested at 100% power in the artificial chamber and cadaver eye. Runs were completed with aspiration blocked. Temperature was continuously measured on the phacoemulsification sleeve using a microthermistor probe connected to the BAT-10 multipurpose thermometer, with an accuracy of ±0.1°C.

RESULTS

Transversal FX had a greater temperature increase than micropulse (p < 0.001) and torsional (p < 0.001). Micropulse had a greater temperature increase than torsional (p < 0.001). The cadaver eye had a greater temperature increase than the artificial chamber for torsional (p < 0.001).

CONCLUSIONS

Higher heat accumulation and potential for incisional burn occurred with the cadaver model than with the artificial chamber, suggesting the need for caution when using 100% torsional ultrasound with aspiration blocked. Transversal FX generated more heat than was reported originally. Further study is needed to determine the incidence of incisional burn with varied power settings for this new model. Micropulse generated more heat than previous reports, but the increased efficiency is likely to negate potentially increased incisional burn risk.

Transverse vs torsional ultrasound: prospective randomized contralaterally controlled study comparing two phacoemulsification-system handpieces

PURPOSE

To compare surgical efficiency and multiple early clinical outcome variables in eyes undergoing phacoemulsification using either transversal or torsional ultrasound systems.

SETTING

Assil Eye Institute, Beverly Hills, CA, USA.

DESIGN

Prospective, randomized, clinician-masked, contralaterally controlled single-center evaluation.

PATIENTS AND METHODS

Patients seeking cataract removal in both eyes with implantation of multifocal intraocular lenses were randomly assigned to one of two treatment rooms for phacoemulsification with either a transverse ultrasound system or torsional handpiece system. The contralateral eye was treated at a later date with the alternate device. A total of 54 eyes of 27 patients having similar degrees of cataract, astigmatism, and visual potential were included. All operative data were collected for analysis, and patients were followed for 3 months after surgery.

RESULTS

Similar visual acuity was reported at all postoperative visits between the two groups. Mean phacoemulsification time and total power required were both significantly lower with the transverse system than with the torsional technique (P<0.05 for both). Similarly, mean total balanced salt solution used was significantly less with the transverse system vs torsional (P<0.05). Postoperative safety demonstrated significantly lower endothelial cell loss at 1 day and 1 month (P<0.05) with transverse vs torsional. Macular swelling was less at 1 week, 1 month, and 3 months with transverse vs torsional, although the difference did not achieve significance (P=0.1) at any single time point. Clinically detectable corneal edema was reported less frequently at all postoperative time points with the transverse system.

CONCLUSION

The transverse ultrasound system was found to be possibly associated with less balanced salt-solution use, less phacoemulsification time, and less power required than the torsional phaco system. Postoperative data suggested that improved phaco efficiency may translate to a better overall safety profile for the patient.

The Impact of Reused Phaco Tip on Outcomes of Phacoemulsification Surgery

PURPOSE

To evaluate the impact of reused phaco tip on intraoperative performance and postoperative outcomes after 2.2 mm micro-coaxial torsional and transversal phacoemulsification.

MATERIAL AND METHODS

This prospective randomized study enrolled 136 eyes of 136 cataract patients; 68 eyes in torsional group (34 eyes with single use tip, 34 eyes with reused tip) and 68 eyes in transversal group (34 eyes with single use tip, 34 eyes with reused tip). Intraoperative measurements were total ultrasound (U/S) time, torsional U/S time, cumulative dissipated energy (CDE), estimated fluid use (EFU) in the torsional group and total phacoemulsification time (TPT), and effective phacoemulsification time (EPT) in transversal phacoemulsification. The central endothelial cell density (ECD) and the central corneal thickness (CCT) were evaluated preoperatively and postoperatively at 1 and 30 days using noncontact specular microscopy.

RESULTS

Intraoperative measurements in torsional phacoemulsification showed significant increase in total U/S time (p = 0.01), torsional U/S time (p = 0.01), and CDE (p = 0.01) with the reused tip. The EFU was similar in both tip groups (p = 0.36). The total U/S time, torsional U/S time, and CDE in torsional group were significantly increased with the reused tip for grade III (p = 0.03 for all parameters) and grade IV cataracts (p = 0.005 for torsional U/S time and CDE; p = 0.006 for total U/S time). Intraoperative measurements in transversal phacoemulsification showed no differences in TPT and EPT between tip groups (p > 0.05). The change in ECD and CCT in torsional and transversal phacoemulsification groups were similar in both tip groups (p > 0.05).

CONCLUSIONS

This study showed that sharpness of phaco tip edge increases the efficiency of torsional phacoemulsification for hard cataracts. This result does not mean that reused phaco tip may be used in soft and medium cataracts. As the timing of tip's change is a user-dependent procedure, a new single phaco tip should be used in each case if possible.

Comparison of corneal endothelial changes following phacoemulsification with transversal and torsional phacoemulsification machines

AIM

To compare and evaluate the phacoemulsification parameters and postoperative endothelial cell changes of two different phacoemulsification machines, each with different modes, but also to assess the relationship between postoperative endothelial cell loss and the phacoemulsification parameters, as well as the other factors in both groups.

METHODS

This prospective observational study was comprised of consecutive eligible cataract patients operated with phacoemulsification technique performed by the same surgeon using either a WHITESTAR Signature Ellips FX (transversal, group 1) or Infiniti OZil IP (torsional, group 2) machine.

RESULTS

The study included 86 patients. Baseline characteristics in the groups were similar. The median nuclear sclerosis grade was 3 (2-4) in the first group and 2 (2-4) in the second group (P=0.265). Both groups had similar phacoemulsification needle times (group 1: 60.63±36 s; group 2: 55.98±30 s; P=0.789). The percentage of endothelial cell loss 30d after surgery ranged from 3% to 15% with a median of 7% in group 1, and from 2% to 13% with a median of 6% in group 2; however, there was no statistically significant difference between the groups (P=0.407). Hexagonality (P=0.794) and the coefficient of variation (CV; P=0.142) did not differ significantly between the groups before and 30d after surgery. A significant positive correlation was found between the endothelial cell loss and nuclear sclerosis grade (group 1: P<0.001; group 2: P<0.001) and between the endothelial cell loss and average phacoemulsification power (group 1: P=0.007; group 2: P=0.008).

CONCLUSION

Both of these machines were efficient, with similar endothelial cell loss. This endothelial cell loss was related to the increased nuclear sclerosis grade and increased phacoemulsification power.

Computation of the temperature rise at the corneal endothelium during cataract surgery by modeling of heat generation inside the anterior chamber

The corneal endothelium sustaining the transparency of the cornea is a vulnerable cell layer. Thermal exposure during phacoemulsification is considered to be a potential cause of post-operative cell loss. Knowledge of the temperature rise and particularly of its dependence on region and system settings could deliver useful information about a potential correlation with cell damage. However, there exists a lack of understanding of the process and location of heat generation. Analytical calculations and experiments enabled the quantification of different mechanisms acting as heat sources during phacoemulsification. Heat generation caused by viscous friction was estimated using both an analytical approach and a numerical simulation. In contrast to absorption of sound and self-heating of the probe, this effect was ascertained to be the main heat source. Calorimetric measurement of the power input verified this modeling. On the basis of these results, the local temperature distribution inside a porcine eye was computed time dependently using the finite-element method. Two different amplitude settings were compared with respect to the temperature increase at the corneal endothelium. Various conclusions on the mitigation of thermal exposure during treatment can be drawn from this finite-element simulation.

Thermal imaging comparison of Signature, Infiniti, and Stellaris phacoemulsification systems

Background

To compare the heat production of 3 different phacoemulsification machines under strict laboratory test conditions. More specifically, the thermal behavior was analyzed between the torsional modality of the Infiniti system and longitudinal modalities of the Abbot WhiteStar Signature Phacoemulsification system and Bausch and Lomb Stellaris system.

Methods

Experiments were performed under in-vitro conditions in this study.

Three phacoemulsification handpieces (Infiniti, Signature, and Stellaris) were inserted into balanced salt solution-filled silicone test chambers and were imaged side-by-side by using a thermal camera. Incision compression was simulated by suspending 30.66-gram weights from the silicone chambers. The irrigation flow rate was set at 0, 1, 2, 3, 4, and 5 cc/min and the phacoemulsification power on the instrument consoles was set at 40, 60, 80, and 100%. The highest temperatures generated from each handpiece around the point of compression were measured at 0, 10, 30, and 60 seconds.

Results

Under the same displayed phacoemulsification power settings, the peak temperatures measured when using the Infiniti were lower than when using the other two machines, and the Signature was cooler than the Stellaris. At 10 seconds, torsional phacoemulsification with Infiniti at 100% power showed data comparable to that of the Signature at 80% and the Stellaris at 60%. At 30 seconds, the temperature from the Infiniti at 100% power was lower than the Signature at 60% and the Stellaris at 40%.

Conclusions

Torsional phacoemulsification with the Infiniti generates less heat than longitudinal phacoemulsification with the Signature and the Stellaris. Lower operating temperatures indicate lower heat generation within the same fluid volume, which may provide additional thermal protection during cataract surgery.

Comparative analysis of corneal morphological changes after transversal and torsional phacoemulsification through 2.2 mm corneal incision

Purpose

This paper compares and evaluates the corneal morphological changes occurring after cataract surgery through a 2.2 mm corneal incision. We use two platforms for comparison and evaluation, transversal and torsional phacoemulsification.

Patients and methods

This study includes 139 consecutive cataractous eyes (nuclear color 2–4, according to the Lens Opacities Classification System III [LOCSIII]) of 82 patients undergoing cataract surgery through a 2.2 mm corneal incision. Two different phacoemulsification platforms were used and assigned randomly: we used the WhiteStar Signature^® system with the Ellips™ FX transversal continuous ultrasound (US) mode for group I (mean age: 65.33 ± 6.97 years), and we used the Infiniti^® system with the OZil^® Intelligent Phaco (IP) torsional US mode for group II (mean age: 64.02 ± 7.55 years). The corneal endothelium and pachymetry were evaluated preoperatively and at 1 month postoperatively. Incision size changes were also evaluated.

Results

All surgeries were uneventful. Before intraocular lens implantation, the mean incision size was 2.24 ± 0.06 mm in both groups (P = 0.75). In terms of corneal endothelial cell density, neither preoperative (I vs II: 2304.1 ± 122.5 cell/mm² vs 2315.6 ± 83.1 cell/mm², P = 0.80) nor postoperative (I vs II: 2264.1 ± 124.3 cell/mm² vs 2270.3 ± 89.9 cell/mm², P = 0.98) differences between the groups were statistically significant. The mean endothelial cell density loss was 1.7% ± 1.6% and 2.0% ± 1.4% in groups I and II, respectively. Furthermore, no significant differences between groups I and II were found preoperatively (P = 0.40) and postoperatively (P = 0.68) in central pachymetry. With surgery, the mean increase in central pachymetry was 28.1 ± 23.6 μm and 24.0 ± 24.0 μm in groups I and II, respectively (P = 0.1).

Conclusion

Ellips™ FX transversal and OZil^® IP torsional phacoemulsification modes are safe for performing cataract surgery, inducing minimal corneal thickness and endothelial changes.

Ozil IP torsional mode versus combined torsional/longitudinal microcoaxial phacoemulsification

Purpose.

To compare the safety and efficacy of microcoaxial phacoemulsification surgeries performed with the Ozil Intelligent Phaco (IP) torsional mode and combined torsional/longitudinal ultrasound (US) mode using the Infiniti Vision System (Alcon Laboratories).

Methods.

In this prospective randomized comparative study, 60 eyes were assigned to 2.2-mm microcoaxial phacoemulsification using the Ozil IP torsional mode (group 1) or combined torsional/longitudinal US mode (group 2). The primary outcome measures were US time (UST), cumulative dissipated energy (CDE), longitudinal and torsional ultrasound amplitudes, mean operation time, mean volume of balanced salt solution (BSS) used, and surgical complications.

Results

Both groups included 30 eyes. Mean UST, CDE, and longitudinal and torsional ultrasound amplitudes in group 1 were 1 minute 15±34.33 seconds, 8.74±5.64, 0.43±0.74, and 25.56±8.56, respectively, and these parameters in group 2 were 1 minute 40±51.44 seconds, 9.28±5.99, 3.64±1.55, and 3.71±1.34, respectively. UST and longitudinal amplitudes were found to be significantly low in group 1 (p<0.001, p<0.001), whereas torsional amplitude was found to be significantly high in this group (p=0.001). Mean volumes of BSS used in groups 1 and 2 were 63.30±18.00 cc and 84.50±28.65 cc, respectively (p=0.001).

Conclusions.

The Ozil IP torsional mode may provide more effective lens removal than the combined torsional/longitudinal US mode with a lower UST and volume of BSS used.