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Reiker G Ricks,1,2 Ivan A Cardenas,1,2 Jenna L Jensen,1,2 Tanner K Nelson,1,2 Randall J Olson,1 Jeff H Pettey1 1Department of Ophthalmology and Visual Sciences, John A Moran Eye Center, University of Utah, Salt Lake City, UT, 84132, USA; 2University of Utah School of Medicine, Salt Lake City, UT, 84132, USACorrespondence: Jeff H Pettey, John A Moran Eye Center, University of Utah, 65 Mario Capecchi Drive, Salt Lake City, UT, 84132, USA, Tel +1 801-581-2352, Fax +1 801-581-3357, Email jeff.pettey@hsc.utah.eduPurpose: This study aims to investigate the differences between the heat energy produced during cataract surgery and Cumulative dissipated energy (CDE). CDE is often used as a medium for understanding the energy delivered to the eye during cataract surgery. However, the actual energy produced at the tip level of the tip is not well understood. We propose that a discrepancy may exist between the CDE reported by the surgical machine and the actual energy delivered to the eye.Methods: About 50 mL of distilled water were degassed and placed in an isobaric calorimeter. Using the Alcon Centurion and Ozil handpiece fitted with the balanced tip, an investigator immersed the phaco tip into the water and pressed the foot pedal to position 3. The device was set to 100% continuous power, vacuum to 0 mmHg, with aspiration 12 mL/min aspiration. To prevent system changes in the system within the calorimeter, the aspiration tubing was occluded. Temperature change recorded by another investigator was observed from 0 to 60 seconds. After 60 seconds the first researcher immediately released the pedal and removed the phaco tip from the water. Trials were performed 10 times using solely torsional or longitudinal settings and averaged. CDE also was recorded and averaged.Results: No significant difference was seen in the temperature change or energy calculated in Joules between ultrasound modalities, with torsional producing a magnitude of 163 J and longitudinal producing 172 J (P = 0.2). However, the CDE generated in the 60 seconds period was significantly different, with a magnitude of 61 for longitudinal compared to 24 for torsional (P < 0.001).&#x00A0Conclusion: Significantly more energy was generated using torsional ultrasound than longitudinal at the tip level of the tip. CDE did not appear to accurately reflect these differences. This suggests that other factors should be considered when evaluating CDE and surgical outcomes.Plain Language Summary: This study looked at possible differences between the energy generated during cataract surgery that is reported by the surgical device and the actual energy measured as thermal heat using different machine settings, namely longitudinal and torsional ultrasound. A common metric used for energy delivery to the eye is cumulative dissipated energy. The problem is that this measure accounts for the energy delivered to the eye where the surgical instrument passes through the cornea. Energy that is produced by the rest of the instrument that is inside the eye is less understood, although others have studied postoperative outcomes. We used a method called calorimetry to measure the thermal heat produced by the entire tip and compared this to what the machine reported as cumulative dissipated energy. Calorimetry calculates energy by measuring the change in temperature of liquids. The surgical instrument generated heat in a chamber containing water, and we used the change in temperature to calculate the energy produced by the surgical instrument. We found that longitudinal and torsional ultrasound produced similar heat energy, but the machine reported very different energy. Our results suggest that the machine may not be reporting all of the energy which the surgical instrument produces, and that surgeons may not be able to rely on cumulative dissipated energy to predict operative outcomes.Keywords: Cumulative dissipated energy, phacoemulsification, calorimetry, torsional ultrasound, longitudinal ultrasound

Swapna Nair,1 Ramachandran Unnikrishnan Nair2 1Department of Cataract and Refractive Surgery, 2Department of Vitreoretinal Services, Chaithanya Eye Hospital and Research Institute, Trivandrum, Kerala, India 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. Keywords: thermal imaging, cataract, phacoemulsification, microincision, torsional ultrasound

Torsion mechanical waves have the capability to characterize shear stiffness moduli of soft tissue. Under this hypothesis, a computational methodology is proposed to design and optimize a piezoelectrics-based transmitter and receiver to generate and measure the response of torsional ultrasonic waves. The procedure employed is divided into two steps: (i) a finite element method (FEM) is developed to obtain a transmitted and received waveform as well as a resonance frequency of a previous geometry validated with a semi-analytical simplified model and (ii) a probabilistic optimality criteria of the design based on inverse problem from the estimation of robust probability of detection (RPOD) to maximize the detection of the pathology defined in terms of changes of shear stiffness. This study collects different options of design in two separated models, in transmission and contact, respectively. The main contribution of this work describes a framework to establish such as forward, inverse and optimization procedures to choose a set of appropriate parameters of a transducer. This methodological framework may be generalizable for other different applications. [ABSTRACT FROM AUTHOR]

Background: Comparison of different phacoemulsification parameters remains a frequently debated and methodologically challenging area. The focus of this study was twofold: (1) To suggest an accurate and simple in vivo model for comparison of phaco parameters with the use of femtosecond laser technology. (2) To compare parameters of intelligent phaco (IP) torsional and combination ultrasound modes using the proposed model. Methods: Forty-three eyes underwent femtosecond laser-assisted cataract surgery (FLACS) with the precise division of each nucleus into two equal hemispheres. This approach was applied to compare two variants of phacoemulsification settings. In each case, one hemisphere was removed with the torsional ultrasound (US) with IP, while another hemisphere was evacuated with combination US. Aspiration time, cumulative dissipated energy (CDE), and fluid consumption were measured in all cases. Results: Our approach allows for direct comparison of different phacoemulsification parameters on each half of the same nucleus under identical surgical conditions. When comparison between torsional US with IP and combination US was made, without regard to nucleus density, no statistically significant difference in CDE, aspiration time, and fluid consumption was found. However, in soft cataracts, CDE was lower with the use of torsional US with IP, while aspiration time and fluid consumption demonstrated no proven differences. In hard cataracts, CDE and aspiration time were significantly lower with the use of the combination US mode. Conclusions: The suggested approach of testing different types of phaco settings on equal halves of the same nucleus can be easily applied for quantitative comparisons under identical surgical conditions. The data obtained suggest that IP technology is preferable when compared to a combination US mode for soft lenses while the combined US is more suitable for hard nuclei. [ABSTRACT FROM AUTHOR]

A torsional piezoelectric ultrasonic sensor design is proposed in this paper and computationally tested and optimized to measure shear stiffness properties of soft tissue. These are correlated with a number of pathologies like tumors, hepatic lesions and others. The reason is that, whereas compressibility is predominantly governed by the fluid phase of the tissue, the shear stiffness is dependent on the stroma micro-architecture, which is directly affected by those pathologies. However, diagnostic tools to quantify them are currently not well developed. The first contribution is a new typology of design adapted to quasifluids. A second contribution is the procedure for design optimization, for which an analytical estimate of the Robust Probability Of Detection, called RPOD, is presented for use as optimality criteria. The RPOD is formulated probabilistically to maximize the probability of detecting the least possible pathology while minimizing the effect of noise. The resulting optimal transducer has a resonance frequency of 28[kHz]. [ABSTRACT FROM AUTHOR]

Background: To evaluate the visual outcomes, efficacy, and complications of 23-gauge pars plana vitrectomy followed by phacoemulsification using torsional ultrasound of dense retained lens matter on perfluorocarbon liquids (PFCLs) after complicated cataract surgery. Methods: The case notes of 34 consecutive patients operated upon with retained lens matter after complicated cataract surgery by one surgeon were reviewed. Twenty-one of the 32 cases were able to be managed using the vitrectomy cutter alone, but 13 cases with dense lens matter were managed using 23-G vitrectomy followed by torsional ultrasound of the retained lens via the original corneal incision after floating it up to the pupillary plane on PFCLs. Case notes of these 13 patients were reviewed to ascertain clinical features, results, and any complications. Results: The mean age of the 13 patients was 79 years. The procedure was completed in all cases without using an intravitreal fragmatome. All cases were aphakic prior to vitrectomy surgery. Ten patients had a sulcus fixated IOL inserted at the time of vitrectomy and three had an angle-supported anterior chamber IOL inserted. Mean post-operative visual acuity at 3 months was 0.24 (median 6/9). Eleven of the 13 patients (85 %) had a best postoperative corrected visual acuity of ≥6/12. One patient developed cystoid macular oedema that was successfully treated. There were no cases of retinal detachment. Conclusion: The outcome of 13 patients operated on with transconjunctival vitrectomy with phacoemulsification of dense retained lens matter on top of PFCLs is described. The technique was used successfully, with good visual acuity outcomes and a low complication rate. [ABSTRACT FROM AUTHOR]

A prospective quasiexperimental single blind study was conducted to test the hypothesis that the LOTUS (laparoscopic operation by torsional ultrasound) shears have significant advantage over conventional cutting bipolar forceps when used to divide and coagulate pedicles in gynaecological surgery. Ten university teaching hospital patients between 35 and 51 years of age were recruited. They all underwent elective abdominal hysterectomy and bilateral salpingo-oophorectomy for nonmalignant indications such as fibroids and menorrhagia. The round and infundibulopelvic ligaments were divided with the LOTUS shears or the Power Blade cutting bipolar forceps at open hysterectomy, and the time taken to complete the division was recorded. Two hundred histological samples were examined for thermal damage by the blinded histopathologist. The main outcome measures were the degree of thermal damage on histology, the time taken to divide each structure, and the need for additional haemostasis. Thermal damage was present in 99/200 slides. The LOTUS shears caused thermal damage in 47 sections. The cutting bipolar forceps caused thermal damage in 52 sections. The degree of thermal damage was less with the LOTUS shears. The mean times taken by the LOTUS shears to divide the round ligaments and infundibulopelvic ligaments were 9.24 s and 20.02 s, respectively. The corresponding times for the bipolar forceps were 9.69 s and 27.53 s, respectively. The LOTUS shears were associated with shorter bisection times and less thermal damage in this pilot study. These results were not statistically significant. [ABSTRACT FROM AUTHOR]