Phacoemulsification conditions resulting in thermal wound injury

Phacoemulsification Wound Burn and Its Management

Introduction

The production of ultrasonic energy during phacoemulsification is associated with heat generation that could damage ocular tissues, particularly at the corneoscleral wound site.

Case Presentation

This study presents an 89-year-old patient with senile hypermature cataract and Fuchs endothelial dystrophy developing severe thermal corneoscleral injury during phacoemulsification. At presentation, visual acuity was finger count at 40 cm and there was a 1 × 2-mm area of corneal melting at the corneal tunnel with diffuse corneal oedema. After 1 month, a temporal circular corneal patch graft was applied to the corneal burn. A penetrating keratoplasty was performed 16 months after the first surgery.

Conclusion

Corneal surgery, including lamellar patch grafts and full-thickness penetrating grafts, could be used, when necessary, to restore the cornea's integrity. These procedures could eliminate corneal scarring, decrease astigmatism, and improve vision in patients with phacoemulsification burns.

Effect of low and passive flow on OVD thermal properties during phacoemulsification

OBJECTIVE

To study the thermal properties and response magnitude of a forced-infusion phacoemulsification machine on 4 ophthalmic viscosurgical devices (OVDs).

DESIGN

Experimental study.

METHODS

A phacoemulsification tip, thermocouple, and gauge were placed into an artificial anterior chamber with balanced saline solution (BSS) or approximately 0.1 mL of OVD. Once the thermocouple measured a consistent temperature, the pedal was engaged for 60 seconds; then the tip was removed. The machine was cooled for 5 minutes and flushed with BSS to return to baseline. This was repeated 10 times for each OVD. The research consisted of 2 scenarios: vacuum-blocked flow rate and low aspiration flow rate.

RESULTS

All OVDs showed greater temperature changes than BSS. In the vacuum-blocked scenario, these increases were statistically significant. The medium viscosity dispersive OVD (DiscoVisc) reached temperatures exceeding 60°C. In the low-flow scenario, HEALON5 and DisCoVisc were significantly different at 5 seconds and only HEALON5 at 10 seconds. No temperature increases over BSS were greater than 1.0°C.

CONCLUSIONS

The dispersive, cohesive, and viscoadaptive OVDs demonstrated higher temperature changes than BSS but did not reach the threshold for corneal incision contracture. The study team verified the need for at least a minimal flow rate before ultrasound, which is especially evident in the first 10 seconds, because a flow rate of only 20 mL/minute mitigated OVD-related thermal effects. Understanding thermal responses enables corneal incision contracture risk reduction.

In vitro analysis of clinically relevant aspects of a polymer-coated phacoemulsification tip vs a traditional tip

PURPOSE

To compare the in vitro incisional temperature, acoustic energy, transient cavitation, and turbulence of the polymer-coated hybrid phacoemulsification tip with the balanced tip.

SETTING

Pasteur Ophthalmology Clinic, Vitacura, Santiago, Chile.

DESIGN

Laboratory study.

METHODS

The Centurion Vision System with Active Sentry handpiece was used with tips operated in torsional mode, and stroke was normalized. For thermal measurements, controlled loads were applied over the tip sleeve simulating the pressure applied at the expected level of the corneal incision. Heat generated was recorded on a blackbody filmstrip using infrared imaging. A directional hydrophone provided 360° mapping of acoustic pressure. Cavitation patterns with increasing ultrasound power were imaged with high-speed video recording. Particle image velocimetry was used to evaluate turbulence, streaming, and bubble formation.

RESULTS

The temperature rise for the hybrid and balanced tips was lower than with the control mini-flared Kelman tip ( P ≤ .0001). The hybrid tip generated reduced acoustic output compared with the balanced tip. Ultrasound threshold for cavitation was higher for the hybrid vs balanced tip (55% vs 25%). Fluid turbulence was more evident with the balanced tip compared with the hybrid tip at all flow conditions when normalized for stroke at 60% and 80% power for balanced and hybrid tip, respectively.

CONCLUSIONS

The polymer-coated hybrid tip showed reduced heat generation compared with the control mini-flared Kelman tip and had lower acoustic output, lower cavitation, and lower turbulence compared with the balanced tip, suggesting potential for improved clinical safety.

Effect of Modified Peristaltic Phacoemulsification Device on Efficiency and Post-Occlusion Pressure Surge

Purpose

To evaluate efficiency of grooving, nuclear fragment removal, and changes in pressure control in the Oertli Faros using traditional peristaltic and Speed and Precision (SPEEP) features. The SPEEP mode uses novel peristaltic technology permitting independent control of flow and vacuum.

Methods

A porcine lens model was used with an enclosed chamber simulating the anterior segment. Grooving efficiency is evaluated with flow rates of 10, 30, and 50 mL/min using whole lenses. Lens cubes were emulsified at 20, 40, 60, 80, and 100% power with both SPEEP and non-SPEEP modes. Surge was evaluated with pressure gauges placed on the irrigation tubing and aspiration tubing. Pressure readings were recorded per the following: fluid and vacuum were initiated for 15 seconds, vacuum tubing was occluded for 5 seconds, tubing patency was then re-introduced for 15 seconds. Differences between sensors were recorded.

Results

No significant increase in efficiency was seen with increasing flow rate from 30 to 50 mL/min using SPEEP. No significant differences were shown in lens fragment removal in SPEEP and non-SPEEP modes at any power tested. Pressure difference measurements were not significantly different with SPEEP and non-SPEEP modes.

Conclusion

We showed that lower flow rates show comparable efficiency of grooving when using the SPEEP mode. The SPEEP function did not show increased efficiency in nuclear fragment removal when compared to traditional mode. Surge control was also comparable with both SPEEP and non-SPEEP modes. We suggest that the SPEEP function included in the Oertli Faros may have some advantages.

Effect of surgical microscope and illuminated chopper on anterior chamber temperature

BACKGROUND

To evaluate the effect of the light intensity of the surgical microscope and illuminated chopper on the anterior chamber temperature.

STUDY DESIGN

Experimental study.

METHODS

A model eye (Kitaro WetLab System; FCI Ophthalmics, Pembroke, MA, USA) was used in this experimental study. The illuminance of a surgical microscope (Leica M300; Leica Microsystems, Wetzlar, Germany) and illuminated chopper (iChopper NAM-25 GB; Oculight, Korea) with a light source (iVision; Oculight) was measured using an illuminometer. In addition, the temperature in the anterior chamber of the model eye filled with balanced salt solution when using the surgical microscope with a light intensity from level 1 to level 6 and the illuminated chopper at 99% light intensity was measured for 10 min.

RESULTS

The anterior chamber temperature was increased by 0.2, 0.5, 1.0, and 1.4 ℃ when using the surgical microscope at level 3 (10050 lux), 4 (16490 lux), 5 (24900 lux), and 6 (32500 lux), respectively, for 10 min. The illuminated chopper at 99% light intensity (14893 lux) positioned in the anterior chamber increased the anterior chamber temperature by 0.2° C after 10 min, which was equal to the increase in the temperature caused by the surgical microscope at level 3.

CONCLUSION

The photothermal effect of the illuminated chopper directly positioned in the anterior chamber appeared to be similar to that of a microscope with similar illuminance. Therefore, the illuminated chopper is safe in terms of anterior chamber temperature changes in cataract surgery.

Eyelid and scleral thermal injury following phacoemulsification in silicone oil: a case report

Background

Phacoemulsification has been the mainstay method for extracapsular cataract extraction surgery in the anterior segment; for cases of posterior drop of lens fragments into the vitreous, a posterior segment phacoemulsification instrument (fragmatome; Alcon, Inc., Fort Worth, TX) can be employed to remove the dislocated lens materials. Studies have reported on thermal injury to the cornea during phacmoemulsification of the anterior segment. However, few studies have investigated thermal burn in the simultaneous sclera and eyelid induced by the fragmatome. Currently, there is no reports and lack of optimal strategy for the management of nucleus drop in a vitreous cavity filled with silicon oil.

Case Presentation

We present the case of a 53-year-old male patient with a thermal burn wound on the upper eyelid and sclera following phacoemulsification for a dropped lens in a silicone oil-filled vitreous. We further designed an experiment to verify our hypothesis that thermal injury could be induced by the high temperature of the metal tip during phacoemulsification in silicone oil. In our experiment, during 420 s of continuous ultrasonic wave, the temperature of the fragmatome tip in the balanced salt solution (BSS) increased from 22.0 to 24.0 ºC, while the temperature of the fragmatome tip in the silicone oil group increased from 22.0 to 43.0 ºC.

Conclusions

The temperature of the fragmatome tip increased significantly in silicone oil compared to BSS in the experiment. Thus, physicians should be aware of possible thermal complications when using fragmatome in eyes filled with silicone oil.

Donor Cornea Use in Scleral Surface Reconstruction

Objectives:

To investigate the indications for and results of treating scleral surface problems with donor corneal grafts that are not used in keratoplasty surgery or are left over from keratoplasty.

Materials and Methods:

The records of 16 patients in whom corneal tissue was used to repair a scleral tissue defect or cover an exposed glaucoma drainage implant were evaluated retrospectively. Partial-thickness grafts were prepared using a combined microkeratome system with artificial anterior chamber in 10 eyes and by manual dissection in 3 eyes. Full-thickness grafts were used in 3 eyes.

Results:

There were 8 female and 8 male patients aged 5-79 years (mean: 39.37±24.68). Indications for the use of corneal tissue on the scleral surface were limbal dermoid excision (n=2), pterygium surgery (n=1), intraocular lens removal and scleral fixation intraocular lens (SFIOL) implantation (n=1), exposed SFIOL suture coverage (n=1), trauma (n=2), scleral tissue loss due to repeated glaucoma surgeries (n=5), and exposed glaucoma drainage implant (n=4). The patients were followed for 6-42 months (mean: 14.37±9.14). None of the patients had graft infection, thinning, immunological graft rejection, or vision loss during follow-up. Tectonic lamellar grafts did not adversely affect final visual acuity in any case. At final examination, a good combination of graft and recipient tissue, a smooth ocular surface, and a cosmetic appearance were achieved in all eyes.

Conclusion:

Donor corneas that are not suitable for corneal transplantation or left over from the cornea transplant can be used in patients with scleral tissue loss due to various pathologies and in the treatment of glaucoma drainage implant erosion. In these cases, the use of corneal grafts provides a good ocular surface restoration and cosmetic appearance. The effectiveness and safety of this method should be investigated with large patient series and long follow-up times.

Autologous tenon plug and patch in phacoburn

This 75-year-old woman had phacomorphic angle closure, dense nuclear sclerosis, deep set eye, miotic pupil and tight corneal wound during phacoemulsification. Phacoemulsification wound burn was noted at the end of surgery. Tenon was harvested from the inferior conjunctiva, placed over the gape and anchored by two radial corneoscleral 10-0 nylon. Ten days later, anterior optical coherence tomography showed good wound apposition and sutures were removed with visual recovery to 20/25 (6/7.5) without astigmatism.

Scleral patch grafting for scleral wound thinning after pars plana phacoemulsification and aspiration: A case report

RATIONALE

Here we report the case of a patient who required closure with an autologous scleral patch graft during reoperation after developing marked scleral thinning in the late stage after pars plana phacoemulsification and aspiration (PPPEA). To the best of our knowledge, this is the first reports of the procedure being used for the treatment of a thinned scleral section post PPPEA.

PATIENT CONCERNS

This study involved a 73-year-old woman who had undergone vitreous surgery combined with PPPEA for retinal detachment in her right eye 8 years earlier and subsequently underwent intraocular lens (IOL) ciliary sulcus suture fixation.

DIAGNOSES

She became aware of visual disturbance in her right eye and slit-lamp examination revealed the dislocation of the IOL.

INTERVENTIONS

To remove the dislocated IOL and resuture the nasal loop back onto the ciliary sulcus of the patient's right eye, a 25-guage trocar was placed on the superior temporal side.

OUTCOMES

Subsequent removal of the trocar from the patient's right eye left an approximately 3-mm-wide oval-shaped gap at the trocar insertion site due to extreme thinning of the sclera in that area; that is, the location where the PPPEA was performed. Since suture fixation failed to stop intraocular fluid leakage, an inferior free half-thickness scleral flap was created to patch the scleral wound. Postsurgery, the leakage in that eye stopped and the intraocular pressure was stable. No complications were observed during the 1-year-postoperative follow-up period.

LESSONS

Since thermal injuries during PPPEA may lead to postoperative scleral thinning, surgeons should avoid the site of a prior PPPEA when constructing a scleral wound during reoperation.

Investigation of scleral thermal injuries caused by ultrasonic pars plana phacoemulsification and aspiration using pig eyes

PURPOSE

The purpose of this study was to investigate the thermal injuries caused by ultrasonic pars plana phacoemulsification and aspiration (PPPEA) using pig eyes.

METHOD

Using a 20-gauge (G) vitrectomy system (Accurus^®, Fragmatome; Alcon Laboratories) in both the 'open-tip' and 'closed-tip' techniques, PPPEA was performed in pig eyes and the subsequent thermal injuries generated around the scleral wound were measured by infrared thermal imaging (thermography). Post surgery, the state of the scleral wound was observed under a microscope, and a tissue slice containing the scleral wound was then prepared and observed under an optical microscope.

RESULTS

Thermography measurements revealed a slight temperature rise around the scleral wound in the open-tip case, yet a marked temperature rise in the closed-tip case. The scleral wound incision produced by the open tip was linear, while that produced by the closed tip was expanded. Histological examination revealed mild degeneration of the sclera around the wound in the open-tip case, yet marked tissue degeneration by thermal injuries in the closed-tip case.

CONCLUSION

Our findings showed that in PPPEA, the temperature of the tip of a 20G vitrectomy system rapidly increases due to the closed-tip technique, thus producing obvious thermal damage to the scleral wound. In order to prevent thermal injuries to the scleral wound during PPPEA, it is important to shorten the time of ultrasonic oscillation during surgery as much as possible while the tip is occluded with nuclear fragments.

An evaluation of intraoperative and postoperative outcomes of torsional mode versus longitudinal ultrasound mode phacoemulsification: a Meta-analysis

AIM

To evaluate and compare the intraoperative parameters and postoperative outcomes of torsional mode and longitudinal mode of phacoemulsification.

METHODS

Pertinent studies were identified by a computerized MEDLINE search from January 2002 to September 2013. The Meta-analysis is composed of two parts. In the first part the intraoperative parameters were considered: ultrasound time (UST) and cumulative dissipated energy (CDE). The intraoperative values were also distinctly considered for two categories (moderate and hard cataract group) depending on the nuclear opacity grade. In the second part of the study the postoperative outcomes as the best corrected visual acuity (BCVA) and the endothelial cell loss (ECL) were taken in consideration.

RESULTS

The UST and CDE values proved statistically significant in support of torsional mode for both moderate and hard cataract group. The analysis of BCVA did not present statistically significant difference between the two surgical modalities. The ECL count was statistically significant in support of torsional mode (P<0.001).

CONCLUSION

The Meta-analysis shows the superiority of the torsional mode for intraoperative parameters (UST, CDE) and postoperative ECL outcomes.

Laboratory assessment of thermal characteristics of three phacoemulsification tip designs operated using torsional ultrasound

Purpose

Ultrasound activation of phacoemulsification (phaco) tips can create considerable thermal energy that may increase the risk of tissue damage during cataract surgery. The purpose of this study was to define the thermal profiles of three phaco tip designs in simulated surgical conditions.

Methods

In this laboratory investigation, sleeved phaco tips (mini-flared Kelman^® tip with aspiration bypass port and Intrepid^® Balanced Tip with aspiration bypass port, and MST A1 bent-mini phaco tip (without aspiration bypass) were tested using an ultrasonic phaco device operated in torsional mode at power levels of 50%, 75%, and 100% amplitude. An automated fixture applied a 30 g load to simulate compression against the incision site, leading to friction between the silicone sleeve and the titanium tip. Temperature was recorded by high rate infrared imaging under conditions of free flow and occlusion, which was simulated by clamping the aspiration line. Data were summarized using descriptive statistics.

Results

Baseline temperatures of ~26°C were observed for all tips. During ultrasonic operation at 50%, 75%, and 100% amplitude, temperatures were lower for the mini-flared and balanced tips versus the bent-mini tip, both when load was applied and during occlusion. The bent-mini tip reached temperatures as high as 70°C during occlusion with load when operated at 100% amplitude, whereas the mini-flared tip remained <50°C, and the balanced tip remained <36°C in all test conditions. For the mini-flared and balanced tips, temperature increases during operation were not markedly different from free flow and no-load conditions when occlusion or frictional events were simulated.

Conclusion

In all experiments for each tip design, increasing ultrasound power was associated with greater increases in tip temperature. Tip temperatures increased with applied load, but marked temperature increases during occlusion were observed only with the bent-mini tip. The balanced tip produced minimal thermal peaks in all tests.

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.

Evaluating the different laser fragmentation patterns used in laser cataract surgeries in terms of effective phacoemulsification time and power

PURPOSE

To evaluate the effects of the different fragmentation patterns for the lens nucleus in terms of the effective phacoemulsification time (EPT) and power.

SETTING

Shinagawa LASIK Center, Tokyo, Japan.

DESIGN

Comparison study.

METHODS

Seventy-one eyes of 71 patients had preoperative lens opacity grading based on the Emery-Little Classification (Grade 1 and Grade 2). Eyes underwent femtosecond laser-assisted cataract surgery (Catalys™ Precision Laser System), for capsulotomy and lens fragmentation. For the lens fragmentation, either the quadrants softened (Quadrant) or the quadrants complete (Complete) pattern was used. The mean EPT and phacoemulsification (phaco) power for each cutting pattern of Grades 1 and 2 cataracts were evaluated.

RESULTS

The mean EPT was 28.96 seconds in the Quadrant Group and 16.31 seconds in the Complete Group (P=0.006). The mean phaco power was 8.07% in the Quadrant Group and 4.77% in the Complete Group (P=0.0002). Comparing the Quadrant and Complete Groups of Grade 1 cataract showed no significant difference in EPT (P=0.16), but showed a significant difference in phaco power (P=0.033). Comparing the Quadrant and Complete patterns of Grade 2 cataract showed significant differences in both EPT (P=0.012) and phaco power (P=0.003). Using the Complete pattern showed a 44.7% reduction in EPT and a 40.9% reduction in phaco power when compared to the Quadrant Group.

CONCLUSION

Using the smaller fragmentation pattern in femtosecond laser cataract surgery, the phaco time and power were reduced significantly when compared to the procedure with the larger fragmentation pattern.

Posterior segment nucleotomy for dislocated sclerotic cataractous lens using chandelier endoilluminator and sharp tipped chopper

AIM

To describe a new surgical technique for managing dislocated sclerotic cataractous lens.

METHODS

Six patients with advanced posteriorly dislocated cataracts were operated at a tertiary care centre and analyzed retrospectively. After standard 3 port 23 G pars plana vitrectomy and perfluorocarbon liquid (PFCL) injection, the dislocated white cataract was held with occlusion using phaco fragmatome and then chopped into smaller pieces with a sharp tipped chopper using 25 G chandelier endoilluminator. Each piece was emulsified individually. Following aspiration of PFCL, Fluid Air Exchange was done in all the cases and surgery completed uneventfully.

RESULTS

Best corrected visual acuity (BCVA) in all the patients was better than 6/12 after one month of follow up. No serious complications were noted till minimum 6mo of follow up.

CONCLUSION

Four port posterior segment nucleotomy with a chandelier endoilluminator, fragmatome and a chopper appears to be a safe, easy and effective procedure for managing dislocated sclerotic cataractous nuclei. Ultrasonic energy used and adverse thermal effects of the fragmatome on the sclera may be lesser.

The use of femtosecond lasers in cataract surgery: review of the published results with the LenSx system

PURPOSE

To review the published literature describing the use of the LenSx femtosecond laser technology (Alcon Laboratories, Inc., Fort Worth, TX) in cataract surgery.

METHODS

Literature review.

RESULTS

The LenSx system has been used in more than 200,000 cataract surgery procedures to date. Pre-clinical evaluations have shown that this system produces accurate and reproducible capsulorhexes, and that both the energy required for phacoemulsification and total phacoemulsification time are less than with conventional phacoemulsification. In comparative studies, femtosecond lasers have been shown to produce more precise and reproducible capsulorhexes than manual procedures, and better intraocular lens placement; capsule overlap, circularity of capsulotomy, and centration of the intraocular lens are consistently better with femtosecond lasers than with manual procedures. The improved quality of capsulorhexis and intraocular lens positioning are reflected in favorable visual and refractive outcomes. As with any new technology, there is a significant learning curve: prospective cohort studies have shown that the incidence of intraoperative complications such as suction breaks or anterior capsular tears or tags decreases with experience. In general, the incidence of such complications is within the range (< 2%) considered in recent evidence-based guidelines to be feasible and desirable.

CONCLUSIONS

Although femtosecond laser cataract surgery is in its infancy, the technology is evolving rapidly and offers the potential for more consistent and predictable results after cataract surgery.

Effect of continuous ultrasonic phacoemulsification with anterior chamber maintainer on corneal endothelial damage in hard nuclear cataract

PURPOSE

To study the effects of continuous ultrasonic phacoemulsification performed with and without an anterior chamber maintainer (ACM) on corneal endothelial damage in patients with hard nuclear cataract.

METHODS

Sixty eyes in 60 patients with hard nuclear cataract (grade IV), one lesion per eye, were randomly allocated into 2 groups: continuous ultrasonic phacoemulsification with (group A) or without (group B) ACM. The intraoperative accumulated energy complex parameter (AECP), frequency of shallow anterior chamber, and postoperative corneal incision edema, corneal endothelial cell counts, and visual recovery were compared between the groups.

RESULTS

The intraoperative AECP, postoperative corneal incision edema, and postoperative visual recovery showed no significant differences between the groups (p&gt;0.05). At 1 month postoperatively, the corneal endothelial cell loss rate and hexagonal cell percentage (postoperative compared to preoperative) in groups A and B were 0.117 ± 0.12 and 9.97 ± 9.52% and 0.15 ± 0.73 and 8.5 ± 4.60%, respectively, with no significant difference noted (p&gt;0.05). The endothelial cell mutation rate was significantly lower in group A than in group B at 6.41 ± 6.78% and 28.27 ± 27.95%, respectively (p&lt;0.05). The frequency of intraoperative shallow anterior chamber was significantly lower in group A than in group B (2 vs 17 times, p&lt;0.05).

CONCLUSIONS

Continuous ultrasonic phacoemulsification with ACM is a safe, effective, simple, and easy method to treat hard nuclear cataract and causes minimal damage to corneal endothelial cells. It is an ideal surgical option and is worth popularizing.

Comparison of two different ultrasound methods of phacoemulsification

PURPOSE

To compare the safety and efficacy of microcoaxial phacoemulsification surgeries performed with the OZil Intelligent Phaco torsional mode (Alcon Laboratories, Inc., Fort Worth, USA) and combined torsional/longitudinal ultrasound mode using 45 degree aperture angled tips.

DESIGN

Prospective randomized clinical trial.

METHODS

setting: Maltepe University, Istanbul. patient population: Eighty eyes of 80 cataract patients were randomly assigned to 2.2 mm microcoaxial phacoemulsification using the OZil Intelligent Phaco torsional mode (Group 1) or combined torsional/longitudinal ultrasound mode (Group 2). observation procedure: Intraoperative fluid and energy usage and postoperative examinations were evaluated. main outcome measures: Ultrasound time, cumulative dissipated energy, longitudinal and torsional ultrasound amplitudes, mean operation time, mean volume of fluid used, and surgical complications.

RESULTS

Both groups included 40 eyes. Mean ultrasound time, cumulative dissipated energy, and longitudinal and torsional ultrasound amplitudes in Group 1 were 58.21±33.81 seconds, 7.74±6.23, 0.45±0.30, and 26.30±12.60%, respectively, and these parameters in Group 2 were 64.75±30.23 seconds, 12.61±6.21, 26.32±5.85, and 40.98±8.33%, respectively. Cumulative dissipated energy and longitudinal and torsional amplitudes were found to be significantly lower in Group 1 (P=.001, P<.001, P<.001). Mean volumes of fluid used in Groups 1 and 2 were 73.30±19.87 cc and 107.07±21.82 cc, respectively (P<.001).

CONCLUSION

With the aid of a 45 degree aperture angled tip, the OZil Intelligent Phaco torsional mode provided more effective lens removal than the combined torsional/longitudinal ultrasound mode, with a lower cumulative dissipated energy and volume of fluid used.

Effectiveness and safety of femtosecond laser-assisted lens fragmentation and anterior capsulotomy versus the manual technique in cataract surgery

PURPOSE

To evaluate the effectiveness and safety of cataract surgery using femtosecond laser-assisted lens fragmentation and anterior capsulotomy versus manual cataract surgery.

SETTING

MaxiVision Eye Hospital, Begumpet, Hyderabad, India.

DESIGN

Randomized controlled open-label multisurgeon prospective trial.

METHODS

Patients (at least 18 years old) were randomized to femtosecond laser-assisted lens prefragmentation and capsulotomy or manual capsulorhexis and standard phacoemulsification. Measured outcomes were effective phacoemulsification time (EPT), surgeon-assessed ease of phacoemulsification, mean phaco energy, mean phaco time, balanced salt solution volume, capsulotomy precision, and adverse event rates.

RESULTS

Fifty-six eyes had the femtosecond laser procedure, and 63 had manual cataract surgery. The mean EPT was significantly lower in the laser group (5.2 seconds ± 5.7 [SD]) than in the manual group (7.7 ± 6.0 seconds) (P=.025). There was a significant difference in the mean phaco energy between the 2 groups (13.8% ± 10.3% in laser group; 20.3% ± 8.1% in manual group) (P<.001). There were no significant between-group differences in the ease of phacoemulsification, mean phaco time, or balanced salt solution volume. Laser-assisted capsulotomies were significantly more accurate and precise (intended diameter, circularity, centration) (P<.01). The safety profiles of the procedures were equivalent, with no adverse events at the 1-day follow-up.

CONCLUSION

The femtosecond laser platform was effective and safe in cataract surgery, reducing EPT and the mean phaco energy during lens fragmentation and providing precise and reproducible capsulotomies.

The Ultrachopper tip: a wound temperature study

PURPOSE

To determine the thermal characteristics of the Ultrachopper and its thermal properties in varied viscosurgical substances.

DESIGN

Experimental study.

PARTICIPANTS

Not applicable.

METHODS

The Ultrachopper (Alcon, Inc) tip with the Infiniti (Alcon, Inc) handpiece was attached to a thermistor and placed in a test chamber filled with either an ophthalmic viscosurgical device (OVD) or balanced salt solution (BSS). The thermistor allowed for continuous monitoring of temperature from baseline and the change that occurred over 60 seconds of continuous run time.

RESULTS

Mean maximum temperature in each OVD exceeded 50°C over the first 25 seconds of continuous run time. The mean maximum temperature was statistically significantly higher with all OVDs (p < 0.0001) when compared with BSS. A small but statistically significant difference in mean maximum temperature was shown between Healon 5 (AMO, Inc) and Viscoat (Alcon, Inc) (p < 0.05). The linear increase in temperature was statistically significantly different with all OVDs compared with BSS (p < 0.0001).

CONCLUSIONS

The thermal properties of the Ultrachopper tip demonstrate a heat-generating capacity that achieves published thresholds for risk for wound burn.

Temperature profiles of sleeveless and coaxial phacoemulsification

PURPOSE

To study the temperature profile at the corneal wound during 2 sleeveless techniques versus 2 coaxial phacoemulsification techniques.

SETTING

Department of Ophthalmology, Meir Medical Center, Kfar Saba and Ein-Tal Eye Center, Tel-Aviv, Israel.

DESIGN

Experimental study.

METHODS

Thirty-six porcine eyes were randomized into 4 groups: Group 1: conventional coaxial system (3.0 mm incision); Group 2: coaxial microincision cataract surgery (MICS) system (2.2 mm incision); Group 3: bimanual MICS (1.1 mm incision); Group 4: sleeveless tri-MICS (1.1 mm incision) using a 19-gauge anterior chamber maintainer as the sole fluid source. Temperature measurements were taken using a thermocouple and an infrared thermal imaging system. Measurements were taken in 2 settings; that is, with and without occlusion.

RESULTS

With no occlusion, corneal burns did not occur in any group. However, corneal temperatures were lower with the sleeveless systems (Groups 3 and 4) than with the coaxial systems (Groups 1 and 2) (P=.0003). When occlusion was induced, temperatures were kept constantly low in the sleeveless groups, whereas in the coaxial groups, temperatures increased rapidly, causing corneal burns within seconds. The mean temperature elevations at the incision sites were 39 °C, 48.5 °C, 13.6 °C, and 11.3 °C in Groups 1, 2, 3, and 4, respectively (P<.0001).

CONCLUSIONS

Sleeveless phacoemulsification maintained lower tissue temperatures than sleeved coaxial methods. During occlusion, fluid flow around the naked tip of the sleeveless systems prevented heat accumulation and corneal burns.

Heat profiling of phacoemulsification tip using a thermal scanning camera

An experimental study to measure the heat profile of the phacoemulsification (phaco) tip using standard continuous phaco and hyperpulse phaco with and without waveform power modulation in the Millennium Microsurgical System with Custom Control Software (CCS). The phaco tip was imaged in air using a thermal camera. The highest temperature was measured 15 s after application of phaco power. Continuous, hyperpulse and waveform power modulations of the Millennium Microsurgical System were used with different power settings (20, 50 and 100 %) and duty cycles (40, 60 and 90 %), with the irrigation turned on and off. Using continuous phaco with the irrigation on, the phaco tip temperature remains <28.0 °C. With irrigation off, the temperature is higher compared to irrigation on but still remains <45.0 °C. Comparing the temperatures for all three power modulations when irrigation is on, at each phaco power and duty cycle setting, the temperature of the phaco tip is highest with continuous phaco, followed by hyperpulse with rise time 1, then hyperpulse with rise time 2. When irrigation is off, the highest temperatures are recorded using the hyperpulse with rise time 2, followed by continuous phaco, then hyperpulse with rise time 1. Hyperpulse and waveform modulations reduce heat generation compared to the continuous mode when irrigation is turned on. Lower duty cycles and lower ultrasound power produce less heat at the phaco tip.

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.

Femtosecond laser-assisted cataract surgery with integrated optical coherence tomography

About one-third of people in the developed world will undergo cataract surgery in their lifetime. Although marked improvements in surgical technique have occurred since the development of the current approach to lens replacement in the late 1960s and early 1970s, some critical steps of the procedure can still only be executed with limited precision. Current practice requires manual formation of an opening in the anterior lens capsule, fragmentation and evacuation of the lens tissue with an ultrasound probe, and implantation of a plastic intraocular lens into the remaining capsular bag. The size, shape, and position of the anterior capsular opening (one of the most critical steps in the procedure) are controlled by freehand pulling and tearing of the capsular tissue. Here, we report a technique that improves the precision and reproducibility of cataract surgery by performing anterior capsulotomy, lens segmentation, and corneal incisions with a femtosecond laser. The placement of the cuts was determined by imaging the anterior segment of the eye with integrated optical coherence tomography. Femtosecond laser produced continuous anterior capsular incisions, which were twice as strong and more than five times as precise in size and shape than manual capsulorhexis. Lens segmentation and softening simplified its emulsification and removal, decreasing the perceived cataract hardness by two grades. Three-dimensional cutting of the cornea guided by diagnostic imaging creates multiplanar self-sealing incisions and allows exact placement of the limbal relaxing incisions, potentially increasing the safety and performance of cataract surgery.

Thermal comparison of Infiniti OZil and Signature Ellips phacoemulsification systems

PURPOSE

To determine thermal characteristics of Signature Ellips (Abbott Medical Optics) and Infiniti OZil (Alcon, Inc.) transverse ultrasound and compare both with longitudinal ultrasound in clinically relevant scenarios.

DESIGN

Laboratory investigation.

METHODS

Temperature increase over baseline after 60 seconds was measured in water at positions in 90-degree increments around the sleeve near the proximal needle shaft in an artificial chamber for Ellips and OZil on continuous ultrasound with aspiration blocked and unblocked. This was also done with Signature using longitudinal ultrasound, with and without micropulse (6 ms on, 12 ms off), with aspiration blocked and unblocked, and at the OZil sleeve tip on continuous transverse mode with aspiration unblocked.

RESULTS

OZil (8.1 +/- 0.3 C) had greater temperature increase than Ellips (5.2 +/- 0.3 C; P < .0001) with aspiration unblocked and blocked (29.3 +/- 1.0 C vs 12.2 +/- 0.7 C; P < .0001). OZil had uneven distribution of heat around the shaft (30.1 +/- 0.5 C vs 28.5 +/- 0.6 C; P < .0001), whereas Ellips did not (P = .57). OZil was cooler at the tip (6.6 +/- 0.2 C; P < .0001). Friction in a cadaver eye incision only increased these numbers by 10% (OZil, irrigation blocked).

CONCLUSIONS

Metal stress probably creates heat at the proximal needle junction for both transverse methods. Heat generation differences between OZil and Ellips result from the manner in which they create needle motion. Incision burns may occur, especially for OZil, under nonpulsed settings during fragment removal with occlusion when reaching across the anterior chamber such that the proximal needle shaft came near the wound.

Heat production: Longitudinal versus torsional phacoemulsification

PURPOSE

To compare the heat production of longitudinal versus torsional phacoemulsification under strict laboratory test conditions.

SETTING

Department of Ophthalmology, David Geffen School of Medicine at UCLA, and Jules Stein Eye Institute, Los Angeles, California, USA.

METHODS

Two Infiniti phacoemulsification handpieces were inserted into silicone test chambers filled with a balanced salt solution and imaged serially using a thermal camera. Incision compression was simulated by suspending 25.3 g weights from the silicone chambers. To simulate occlusion of the phacoemulsification tip, the aspiration line was clamped. Peak temperatures were measured 0, 10, 30, 60, and 120 seconds after the commencement of continuous ultrasound power. The 2 handpieces, operating exclusively in longitudinal or torsional modes, were compared 3 ways: (1) using the same power displayed on the instrument console, (2) using identical stroke lengths, and (3) using the same applied energy, a product of stroke length and frequency.

RESULTS

For all 3 comparisons, torsional phacoemulsification resulted in lower temperatures at each time point. At the same displayed power setting, the scenario most familiar to cataract surgeons, longitudinal phacoemulsification elevated temperatures up to 41.5 degrees C more than torsional phacoemulsification.

CONCLUSIONS

Torsional phacoemulsification generated less heat than longitudinal phacoemulsification in all 3 comparison tests. Lower operating temperatures indicate lower heat generation within the same volume of fluid, and this may provide additional thermal protection during cataract surgery.

Cryoirrigation in phacoemulsification facilitates a quicker cornea endothelia recovery

OBJECTIVE

To compare the recovery of cornea endothelia after phacoemulsification (phaco) with anterior chamber irrigation at different temperatures.

STUDY DESIGN

A between-group design was used.

PARTICIPANTS

Thirty-eight patients with cataract.

METHODS

Phaco was done on 40 eyes in these patients with exactly the same procedure except for the temperature of the anterior chamber: cryoirrigation at 12 masculine C for group 1 and at room temperature (25 masculine C) for group 2, 20 eyes in each group, randomly distributed. The cornea edema, keratic precipitate (KP), and anterior chamber flare were observed with micro-slit lamp and graded on a 4-point scale at 1, 3, and 7 days after surgery and compared between groups.

RESULTS

The corneas in group 1 were found to be clearer than those in group 2 at 1 and 3 days after surgery. The difference was statistically significant (p < 0.05) in favour of group 1, suggesting a lighter reaction of cornea endothelia and a quicker recovery in group 1 after the surgery with cryoirrigation. Corresponding recovery in group 2 was found to occur latterly between day 3 and day 7. However, the recovery in both groups was complete, yielding no difference between groups, at day 7 after surgery. In addition, no significant difference was found in Tyndall phenomenon and KP between groups.

CONCLUSIONS

Cryoirrigation during phaco could reduce postoperative cornea edema and promote recovery. The result advocates the use of cryoirrigation in clinic.

Effect of incisional friction and ophthalmic viscosurgical devices on the heat generation of ultrasound during cataract surgery

PURPOSE

To determine the thermal features of the Legacy (Alcon) and Sovereign (Advanced Medical Optics) phacoemulsification machines in a cadaver eye and with 7 ophthalmic viscosurgical devices (OVDs).

SETTING

In situ and in vitro study.

METHODS

Temperature without occlusion was recorded at the sleeve placed in the wound of a cadaver eye, and temperature over baseline was determined after 60 seconds. The result was then compared with the results in a previous study that used balanced salt solution (BSS) in artificial chambers. In the second portion of the experiment, with irrigation and aspiration lines occluded, temperature was recorded at the sleeve placed in an artificial chamber filled with sodium hyaluronate 2.3% (Healon5), sodium hyaluronate 1.4% (Healon GV), sodium hyaluronate 1.0% (Healon), sodium hyaluronate 1.6% (Amvisc Plus), sodium hyaluronate 1.0% (Provisc), sodium hyaluronate 3.0%-chondroitin sulfate 4.0% (Viscoat), or hyaluronate 3.0% (Vitrax). Temperature over baseline was also determined after 60 seconds. These results were compared with each set of OVD data and with the results in the prior BSS study.

RESULTS

In the eye-bank model, the Legacy machine had a 62% temperature increase from incisional friction and the Sovereign machine had a decrease of 8.6% over results in an artificial anterior chamber. The OVD temperature increases were greater for the Sovereign (P<.001) and followed the same general trend for the Legacy. The least temperature increase was with Amvisc Plus, Healon, and Healon GV; the intermediate increases were with Provisc and Vitrax; and the greatest increases were with Viscoat and Healon5. The OVD findings did not correlate with viscosity or pseudoplasticity.

CONCLUSIONS

Incisional friction alone increased heat generation in the Legacy, a stroke-length driven instrument, more than in the Sovereign, a power-driven instrument. Ophthalmic viscosurgical devices are not only a concern due to outflow occlusion but can also add up to 6 times the heat in comparison with BSS. The need to aspirate the OVD before using ultrasound is thus verified.

Thermal study of bare tips with various system parameters and incision sizes

PURPOSE

To identify major and minor surgeon-controlled parameters that affect incision temperature when performing microincision lens removal using the Alcon Infiniti Vision System.

SETTING

In vitro research and development laboratory, Alcon Research, Irvine, California, USA.

METHOD

Phacoemulsification was performed in eye-bank cadaver eyes and the following parameters evaluated: incision, duty cycle, ultrasound (US) power, aspiration flow rate (AFR), vacuum, pulse, bottle height and balanced salt solution temperature, and tip design/size. Each parameter was varied while the others remained constant. The resulting temperature of the incision and US tip was measured using a thermal camera.

RESULTS

Major contributors to elevated incision temperature included incision size, US power, duty cycle, AFR, vacuum setting, tip design, and presence of an ophthalmic viscosurgical device (OVD). Minor contributors included pulse frequency, bottle height, and temperature of the infusate.

CONCLUSION

Microincision lens removal can be performed at safe temperatures with the knowledgeable selection of surgeon-controlled parameters.

Thermography used for analysis and comparison of different cataract surgery procedures based on phacoemulsification

Thermography has been employed to analyze and compare three cataract surgery procedures performed in vivo with phacoemulsification, namely, the Sovereign phacoemulsification system with a traditional technique, the Sovereign WhiteStar phacoemulsification system with a traditional technique and the Sovereign WhiteStar phacoemulsification system with a bimanual technique. During the entire surgical procedure, the temperature of the ocular surface was monitored. The temperature values in the area where the phaco probe was inserted in the eye were measured, and the quantities of heat transmitted to the eye in the different procedures were assessed through suitable indices. In this study the highest temperature measured for each procedure during the surgical operation was 44.9 degrees C for the Sovereign phacoemulsification system with a traditional technique, 41 degrees C for the Sovereign WhiteStar phacoemulsification system with a traditional technique and 39.5 degrees C for the Sovereign WhiteStar phacoemulsification system with a bimanual technique, which is also the surgical procedure having the lowest thermal impact on the eye, i.e., the one in which the temperature peaks are lowest in amplitude and the least amount of heat is transmitted to the eye. Thermography, used in this study as a temperature monitoring instrument, has allowed analysis to be effected through a useful and advantageous methodology, totally non-invasive as regards both surgeon and patient, and has been applied in vivo without requiring any change in the surgical procedure.

Thermal imaging study comparing phacoemulsification with the Sovereign with WhiteStar system to the Legacy with AdvanTec and NeoSoniX system

PURPOSE

To assess intraoperative thermal levels at the wound site during divide-and-conquer phacoemulsification with the Sovereign with WhiteStar (SWS) system or the Legacy with AdvanTec and NeoSoniX (LAD) system.

DESIGN

Prospective, randomized, parallel-group, comparative study.

METHODS

Twenty-six subjects from a private clinical practice underwent divide-and-conquer phacoemulsification with either the SWS system or the LAD system. CB/CF settings (60%/33% duty cycles) were utilized with SWS and 12 pulses per second with the LAD system. Key criteria assessed were peak wound-site temperature, mean temperature change at the wound site, effective phaco time, average phaco power, procedure time, amount of BSS used, and surgical complications.

RESULTS

Mean temperature change at the wound site was greater for the LAD than the SWS group. There was a statistically significant difference (P=.0002) in mean peak wound temperatures, with the LAD group having higher mean peak temperatures (42.47+/-5.33 degrees C) than the SWS group (36.59+/-1.33 degrees C). Highest wound-site temperature was 51 degrees C for the LAD group and 39.3 degrees C for the SWS group. A statistically significant difference (P=.0031) in mean peak temperature was found between the LAD and SWS systems for subjects with a cataract density of 4: higher mean peak temperatures were observed for LAD patients with a cataract density of 4.

CONCLUSIONS

Our findings show that phacoemulsification using the SWS system results in lower peak temperatures and less temperature change at the phaco wound site compared with the LAD system.

Comparison of thermal features associated with 2 phacoemulsification machines

PURPOSE

To determine the thermal characteristics of the Legacy Advantec and Sovereign WhiteStar phacoemulsification machines during different clinically relevant scenarios.

SETTING

In vitro study.

METHODS

In water, temperature was recorded continuously on the sleeve in an artificial chamber, and the increase in temperature over baseline after 60 seconds of ultrasound was determined. This was done for continuous ultrasound, 50 ms on and 50 ms off (pulse), 6 ms on and 12 ms off (WhiteStar; Sovereign only) with aspiration blocked and not blocked, and with 100 g and 200 g weights suspended from the sleeve.

RESULTS

Comparing temperature increase per 20% machine power increments, Sovereign ran hotter than Legacy Advantec for continuous ultrasound (2.31x) and pulse (2.23x). Blocking aspiration increased temperature over the unblocked state. Pulsing decreased temperature by 51% (Legacy Advantec, pulse), 52% (Sovereign, pulse), and 64% (WhiteStar). Weights had much more effect on the Legacy Advantec: 3.5 times more going from baseline to 100 g weights and 3.2 times more going from 100 to 200 g weights. For all these comparisons, the P value was less than 0.0001.

CONCLUSIONS

The machines behaved fundamentally differently, with the Legacy Advantec controlling stroke length and Sovereign controlling a fixed power at any setting. Therefore, workload had a much bigger impact on Legacy Advantec thermal characteristics. Pulsing decreased heat produced directly related to the duty cycle. The most dangerous incision burn scenario is with continuous ultrasound, aspiration blocked, and a heavy workload.

Quantitative thermographic analysis of viscoelastic substances in an experimental study in rabbits

PURPOSE

To measure the temperature parameters on the corneal surface during the delivery of standardized ultrasound energy assisted with ophthalmic viscosurgical devices (OVDs) or different temperatures of irrigating solutions in an experimental animal model.

SETTING

Department of Ophthalmology and Visual Rehabilitation, Medical University of Lodz, and Central Institute for Labor Protection, National Research Institute, Warsaw, Poland.

METHODS

Thirty rabbits (60 eyes) were randomly divided into 6 groups in which different OVD or balanced salt solutions (BSS) were used: group 1: Viscoat (sodium hyaluronate 3%-chondroitin sulfate); group 2: Provisc (sodium hyaluronate 1%); group 3: soft-shell technique; group 4: Celoftal (hydroxypropyl methylcellulose 2%); group 5: BSS 22 degrees C; and group 6: BSS 4 degrees C. After the nucleus and lens cortex were removed, the anterior chamber was filled with OVD or BSS and a phaco tip was introduced into the pupillary plane and switched on. The same phaco tip parameters were used in all groups. For thermographic measurements (ie, maximal temperature [MT], dynamic rise in temperature [DRT], and time when the maximal level of temperature [TMLT] was achieved), a thermocamera was used.

RESULTS

Mean preoperative temperature on the rabbit corneal surface was 22.76 degrees C +/- 1.48 degrees C (SD). Working with a phaco tip increased the temperature in each group. A significantly higher MT was observed in group 5 (27.85 degrees C +/- 0.52 degrees C), followed by group 2 (27.75 degrees C +/- 0.54 degrees C), group 3 (27.74 degrees C +/- 0.46 degrees C), and group 4 (27.25 degrees C +/- 0.60 degrees C), than in group 6 (26.81 degrees C +/- 0.34 degrees C) and group 1 (26.52 degrees C +/- 0.48 degrees C) (P<.05). Significantly higher values of DRT and shorter TMLT values were observed in group 5 (1.16 degrees C/s +/- 0.42 degrees C/s, 4 seconds) and group 6 (0.91 degrees C/s +/- 0.13 degrees C/s, 5 seconds) than in groups 2, 3, 1, and 4 (0.09 degrees C/s +/- 0.07 degrees C/s, 30 seconds; 0.08 degrees C/s +/- 0.04 degrees C/s, 40 seconds; 0.07 degrees C/s +/- 0.03 degrees C/s, 45 seconds; 0.06 degrees C/s +/- 0.02 degrees C/s, 50 seconds, respectively) (P<.0001).

CONCLUSIONS

Currently used OVDs potentially offer different levels of protection against the increase in temperature that occurs during phacoemulsification. Therefore, the surgeon should consider this aspect when choosing an OVD, particularly in difficult cases (ie, hard nucleus, shallow anterior chamber, endothelial abnormalities).

In-air thermal imaging comparison of Legacy AdvanTec, Millennium, and Sovereign WhiteStar phacoemulsification systems

PURPOSE

To compare the temperature profiles of 3 popular phacoemulsification units (Alcon Legacy AdvanTec, Bausch & Lomb Millennium, and AMO Sovereign WhiteStar) under similar operating conditions in air.

SETTING

Jules Stein Eye Institute and the Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.

METHODS

Phacoemulsification probes from the 3 units were placed side by side in air and imaged in the infrared region using model P60 ThermaCAM (Flir Systems). The highest temperature produced by each probe was measured 10 seconds and 30 seconds after power application. Testing was performed under conditions that might produce a corneal burn during cataract surgery. Irrigation flow was set at the low rate of 1 cc/min to simulate a tight incision. Aspiration flow was set at 0 cc/min to simulate occlusion of the needle lumen. Wound compression was simulated in some tests by suspending 22.6 g weights by rubber bands from the silicone sleeves. Manufacturers' specific and identical silicone sleeves were used to evaluate possible variations in thermal conductivity. The AdvanTec Legacy and Millennium were operated in pulse mode at 15 Hertz; 50% duty cycle; and 10%, 30%, and 50% power. The Sovereign WhiteStar was operated in both C/F (56 Hz, 33% duty cycle) and C/L (33 Hz, 20% duty cycle) modes at the same console power settings. Temperature profiles were determined at a variety of power settings with each system operating in continuous and pulse mode.

RESULTS

Under all experimental conditions (at 10%, 30%, and 50% powers; with and without external weights suspended from the phacoemulsification probes; with manufacturers' and identical silicone sleeves; and in continuous and pulse modes), the Millennium and the Sovereign WhiteStar generated higher temperatures than the Legacy AdvanTec.

CONCLUSIONS

Under controlled operating conditions in air and under a variety of power, load, and duty-cycle settings, the Millennium and the Sovereign WhiteStar, operating in both pulse and continuous modes, generated higher peak temperatures than the Legacy AdvanTec.