Longitudinal Phacoemulsification Research Articles

A PROSPECTIVE COMPARATIVE STUDY ON ENDOTHELIAL CORNEAL CELL AFTER CATARACT SURGERY USING TORSIONAL VS LONGITUDINAL PHACOEMULSIFICATION

Objectives: Our aim was to compare endothelial corneal cell changes after cataract surgery performed with Torsional and Longitudinal phacoemulsification in patient with senile cataract. Methods: In this prospective study, the patients were divided into two groups, 24 eyes underwent cataract surgery using Torsional (OZil Infiniti Vision System, Alcon) and 23 eyes using Longitudinal phacoemulsification (Stelaris, Bausch & Lomb). Preoperative, 1 day, and 1-week post-operative examinations on endothelial corneal cells were performed using specular microscope. Cataracts were subdivided according to the LOCS III grading of nucleus. Intraoperative parameters using phacoemulsification time were evaluated. Results: On the results of CCT at 1 day and 1-week post-operative, there were significant changes in group Torsional and Longitudinal 601±68.67; 562.22±45.48 (p=0.033) and 561,71±36,37; 519.52±79.93 (p = 0.015). However, there were no significant changes of CD, CV, HEX 1 day and 1 week post operatively between two groups. The phacoemulsification time was lower in group Torsional 17.11±15.86 seconds than group Longitudinal 18.53±15.46 seconds (p=0.595) but not significantly different. Conclusions: Torsional phacoemulsification outperforms the Longitudinal with a lower phacoemulsification time on soft and medium cataracts, but the differences were not significant. Torsional caused more corneal edema at 1 day and 1 week postoperative significantly and more endothelial cell losses but insignificantly.

Comparative study between torsional phacoemulsification and longitudinal phacoemulsification in their effect on corneal endothelium using specular microscopy.

Comparative study between torsional phacoemulsification and longitudinal phacoemulsification in their effect on corneal endothelium using specular microscopy.

Qualitative Alterations on Corneal Endothelial Cell Morphometry and Hexagonality After Cataract Surgery.

AimTo deeply analyze quantitative and qualitative changes of corneal endothelium after longitudinal phacoemulsification.MethodsIn this prospective interventional case series study, 50 eyes with age-related cataract have been evaluated preoperatively, intraoperatively and postoperatively. The measured parameters were surgically induced endothelial cell loss (ECL), average endothelial cell area (AVG) and hexagonality (HEX).ResultsThe relationship among the measured parameters and the energy dissipated during the two phases of phacoemulsification, sculpting and quadrant removal, has been analyzed with regard to the 5-score harm scale, a new method suggested to categorize cataracts. Two phases of phacoemulsification are linearly related (r = 1.5, P < 0.001, r2 = 79%). Plus, a quadratic model described the correlation between the percentages of ECL and AVG (P < 0.0001), while there was no specific model for the correlation between ECL and HEX.ConclusionThe 5-score harm scale allows to predict the mean changes in percentages of ECL, AVG and HEX of endothelial cells after longitudinal phacoemulsification. Also, this study confirms that the main damage on corneal endothelium is due to the energy delivered in the second phase of phacoemulsification.

Propensity and quantification of aerosol and droplet creation during phacoemulsification with high-speed shadowgraphy amid COVID-19 pandemic.

To study propensity of aerosol and droplet generation during phacoemulsification using high-speed shadowgraphy and quantify its spread amid COVID-19 pandemic. Aerosol and droplet quantification laboratory. Laboratory study. In an experimental set-up, phacoemulsification was performed on enucleated goat eyes and cadaveric human corneoscleral rims mounted on an artificial anterior chamber. Standard settings for sculpt and quadrant removal mode were used on Visalis 100 (Carl Zeiss Meditec AG). Microincision and standard phacoemulsification were performed using titanium straight tips (2.2 mm and 2.8 mm in diameter). The main wound incisions were titrated equal to and larger than the sleeve size. High-speed shadowgraphy technique was used to detect the possible generation of any droplets and aerosols. The visualization and quantification of size of the aerosols and droplets along with calculation of their spread were the main outcome measures. In longitudinal phacoemulsification using a peristaltic pump device with a straight tip, no aerosol generation was seen in a closed chamber. In larger wounds, there was a slow leak at the main wound. The atomization of balanced salt solution was observed only when the phacoemulsification tip was completely exposed next to the ocular surface. Under this condition, the nominal size of the droplet was approximately 50 µm, and the maximum calculated spread was 1.3 m. There was no visible aerosol generation during microincision or standard phacoemulsification. Phacoemulsification is safe to perform in the COVID-19 era by taking adequate precautions against other modes of transmission.

Corneal Endothelial and Central Corneal Thickness Changes after non Complicated Uneventful Phacoemulsification

Aim of the work: this study aimed to evaluate the central corneal thickness and the corneal endothelium by specular microscopy in torsional phacoemulsification versus longitudinal phacoemulsification. Methods: in our study we did a comparative analysis of the changes in endothelial cells of the cornea (Central cell density and cell loss) and central corneal thickness after cataract extraction surgeries by torsional phacoemulsification versus longitudinal phacoemulsification. In our study thirty eyes of thirty patients were chosen from Ophthalmology clinic at Bab Al-Shaariah University Hospital for uneventful phacoemulsification surgeries (15 eyes of 15 patiens for torsional phaco and 15 eyes of 15 patients for longitudinal phaco). The types and densities of cataract were determined as cortical, posterior supcapsular (PSC), nuclear I, nuclear II and nuclear III. Divide and Conquer technique was used for phacoemulsification using (Infiniti, Ozil technology, Alcon) phaco machine. A noncontact specular microscope Topcon SP-1P (Topcon Corporation, Japan) was used to evaluate the central endothelial cell density (CD) and central corneal thickness (CCT). Results: The mean U/S time was lower in the torsional group than in the longitudinal group (p 0.05) and higher average corneal endothelial cell losses at 2 weeks postoperative (p > 0.05). Conclusions: our study suggested a better efficiency by the torsional mode rather than the longitudinal mode.

Evaluation of the corneal endothelium by specular microscopy in torsional phacoemulsification versus longitudinal phacoemulsification

Objective The objective of this study was to compare the effect of cataract extraction by torsional and longitudinal phacoemulsification on the integrity of the corneal endothelium. Background Endothelial cell loss remains a well-known, undesirable side effect of cataract surgery. Torsional phaco has a lower mean needle time, less chatter, and improved followability compared with longitudinal phaco. Patients and methods This is a prospective randomized study for comparative analysis of corneal endothelial modifications (central cell density and cell loss) following torsional versus longitudinal phaco. A total of 50 eyes included had nuclear cataract grade 3. Divide-and-conquer technique was used for surgeries using Infiniti, Ozil Technology phacomachine. Cases were distributed randomly into two groups: group I included 25 eyes for which torsional phaco surgery was performed, and group II included 25 eyes for which longitudinal phaco surgery was performed. Results In group I, the P value that expresses the change between preoperative and postoperative endothelial counts was 0.001, which is statistically significant (P 0.05) between the two groups. Conclusion There was no significant difference on comparing the two types of phacoemulsification, as regards the postoperative corneal endothelial cell loss and best-corrected visual acuity.

A Pilot Study to Propose a "Harm Scale", a New Method to Predict Risk of Harm to the Corneal Endothelium Caused by Longitudinal Phacoemulsification, and the Subsequent Effect of Endothelial Damage on Post Operative Visual Acuity.

PurposeTo study the effect of longitudinal phacoemulsification energy on corneal endothelium and to evaluate the relationship between changes of endothelial cells and postoperative visual acuity.MethodsThis prospective clinical observational cohort study included 50 patients with cataract who underwent longitudinal phacoemulsification. Sequential quantitative and qualitative morphometric endothelial cell analyses of the cornea were performed 4 weeks preoperatively and 6 weeks postoperatively using noncontact specular microscopy.ResultsThere was a relationship between ECL percentage (ECL%) and the 5-score harm scale, well-described by a linear model (one-way ANOVA, R2 = 73.3%). Analyzing the distribution of ECL% Mean with Tukey post-hoc pairwise comparison test (P < 0.001), the value of ECL = 20% has been regarded as cut-off to discriminate patients who obtained an excellent postoperative best-corrected visual acuity (BCVA > 85 letters) from those who just had a good visual outcome (BCVA ≤ 85 letters). There was a significant correlation among the 5-score harm scale, phaco energy intraoperatively delivered, and average cell area postoperatively.ConclusionsThe 5-score harm scale, a new method that enables to pigeonhole cataracts taking into account nucleus hardness and phaco times, allows to predict the harm on corneal endothelium after longitudinal phacoemulsification. Assessment of ECL% permits to discriminate between patients with excellent BCVA and with just good BCVA, postoperatively.

Bent versus straight tips in micropulsed longitudinal phacoemulsification

ObjectiveThe aim of this study was to evaluate bent and straight phacoemulsification tips to determine which tip is more efficient in removal of lens fragments, using micropulsed longitudinal ultrasound in phacoemulsification. DesignIn vitro laboratory study. MethodsThe John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, was the study setting. Pig lenses hardened in a manner comparable with dense human cataracts were cut into 2-mm cubes and removed with micropulsed longitudinal ultrasound using settings previously shown to be optimally efficient (6 milliseconds on and 6 milliseconds off for a bent tip). To verify this time as most efficient for a straight tip, we also tested times of 5, 6, and 7 milliseconds time on and off. The tips were either straight or with a 20-degree bend. Twenty cubes were used for each comparative run. ResultsFor the straight tip, 6 milliseconds on (1.56 ± 0.815 seconds) was significantly more efficient than 7 milliseconds on (2.45 ± 1.56 seconds, p = 0.001) and not significantly more efficient than 5 milliseconds on (1.69 ± 0.86 seconds, p = 0.43). Five milliseconds off time (1.45 ± 0.76s) was more efficient than 6 milliseconds (2.06 ± 1.37 seconds, p = 0.004) and 7 milliseconds off (2.18 ± 1.24s, p = 0.001). The straight tip was more efficient than the bent tip (1.38 ± 0.83 versus 2.93 ± 2.14 seconds, p = 0.006). ConclusionsResults are contrary to accepted common belief. Micropulsed longitudinal phacoemulsification is more efficient with a straight rather than a bent tip.

Effect of torsional versus longitudinal phacoemulsification on the corneal endothelium

Background/aim The present study aims to compare postoperative endothelial outcome after cataract surgery performed with longitudinal phacoemulsification with that performed with torsional phacoemulsification in patients with senile cataract. Patients and methods In this prospective observational study, 20 eyes with senile cataract of different grades of nuclear hardness underwent phacoemulsification by means of a 2.8-mm clear corneal incision using Ozil IP, 10 of which underwent torsional phacoemulsification and 10 underwent longitudinal phacoemulsification. Central endothelial cell counts were taken in all patients preoperatively, at 1 week, 1 month, and 3 months postoperatively. Results The study included 20 patients with age-related cataract whose ages ranged from 55 to 64 years. There was highly statistically significant endothelial cell loss throughout the study in the two groups and also significant endothelial cell loss between the two groups by the third month ( P = 0.02). Conclusion Both torsional and longitudinal phacoemulsification techniques were efficient in removing noncomplicated cataract; however, statistically significant endothelial cell loss was noted, especially with longitudinal phacoemulsification.

Comparison of Clinical Outcomes between Torsional and Longitudinal Phacoemulsification

Comparison of Clinical Outcomes between Torsional and Longitudinal Phacoemulsification

Phacopower Modulation and the Risk for Postoperative Corneal Decompensation

In compromised corneas, eg, patients with Fuchs endothelial dystrophy (FED), it is of utmost importance to use a phacotechnique that is the least traumatic to the corneal endothelium. Furthermore, preoperative patient selection is crucial, because unexpected corneal decompensation leads to dissatisfied patients. To compare corneal thickness and corneal volume changes using torsional and longitudinal phacoemulsification in patients with Fuchs endothelial dystrophy (FED) and determine risk factors of postoperative corneal decompensation. Prospective randomized clinical trial of all patients diagnosed with FED and planning to undergo cataract surgery for visually significant cataract at a university medical center from November 2008 to May 2010. Fifty-two eyes with FED and visually significant cataract underwent torsional (n = 26) or longitudinal (n = 26) phacoemulsification. Patients were evaluated preoperatively and 1 day, 1 week, 1 month, 3 months, and 6 months postoperatively. Visits included best spectacle-corrected visual acuity, anterior segment optical coherence tomography evaluating central corneal thickness (CCT) and peripheral corneal thickness (PCT), and Scheimpflug imaging calculating corneal volume (CV). Randomization took place according to stage of FED, nucleus density grade, and age. Intraoperatively, ultrasonography time and cumulative dissipated energy were recorded. Central corneal thickness, PCT, and CV. Ultrasonography time and cumulative dissipated energy were significantly lower in the torsional group for harder nucleus density grades compared with the longitudinal group (P = .009 and P = .002, respectively). Peripheral corneal thickness at the 6-o'clock position, CCT, and CV were significantly smaller in the torsional group 1 day postoperatively (P = .002; P = .03; and P = .004, respectively). Changes in PCT at the 12-o'clock position and best spectacle-corrected visual acuity were not significantly different between the 2 groups (P > .05). Preoperative CCT was the only significant predictor of corneal decompensation postoperatively (P < .001). Preoperative CCT of 620 µm corresponded to an odds ratio of 1, meaning no increased risk of developing corneal decompensation. For each 10-µm increase in preoperative CCT, the odds of developing corneal decompensation increased 1.7 times. Torsional phacoemulsification effectively reduces ultrasonography time and cumulative dissipated energy compared with longitudinal phacoemulsification in patients with FED. However, there were only significant differences in corneal thickness and CV changes at 1 day postoperatively in favor of the torsional group. Central corneal thickness more than 620 µm, measured by noncontact pachymetry, leads to an increased risk for corneal decompensation after phacoemulsification in patients with FED. clinicaltrials.gov Identifier: NCT00781027.

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

BackgroundTo 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.MethodsExperiments 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.ResultsUnder 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%.ConclusionsTorsional 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.

Long-Term Comparison of Endothelial Changes Between Torsional and Longitudinal Phacoemulsification.

The objective of this study was to evaluate endothelial changes between torsional and longitudinal phacoemulsification 2 years after cataract surgery. This was a prospective, randomized, controlled clinical trial. We enrolled 200 patients with senile cataract between August 2008 and December 2009 for surgery using either torsional (group A, n = 100) or longitudinal (group B, n = 100) phacoemulsification. Outcomes were central endothelial cell density and corrected distance visual acuity (CDVA) 3 months and in this follow-up 2 years after surgery. Statistical evaluation of endothelial cell loss (ECL) was performed according to statistical guidelines by creating a primary analysis (substitution of missing values by the median) and a secondary analysis (actual data). The mean age was 71 (SD, 7.3) years. We were able to reexamine 46 patients in group A and 54 in group B 2 years after surgery. The median CDVA before surgery was 0.3 logMAR in group A and 0.35 logMAR in group B, improving to 0 logMAR postoperatively in both groups. The median ECL in the primary analysis was 6.9% after 3 months and 10.3% 2 years after surgery in group A. In group B, we found a loss of 6.6% after 3 months and 8.6% 2 years postoperatively. In the secondary analysis, the loss was 10.0% in group A and 8.5% in group B after 2 years. The difference was statistically not significant. There is no difference between the ECL between torsional and longitudinal phacoemulsification up to 2 years after cataract surgery.

Comparison of endothelial changes and power settings between torsional and longitudinal phacoemulsification

To compare the intraoperative and postoperative outcomes of conventional longitudinal phacoemulsification and torsional phacoemulsification. Department of Ophthalmology, University of Leipzig, Germany. Randomized single-center clinical trial. Eyes with senile cataract were randomized to have phacoemulsification using the Infiniti Vision System and the torsional mode (OZil) or conventional longitudinal mode. Primary outcomes were corrected distance visual acuity (CDVA) and central endothelial cell density (ECD), calculated according to the Conference on Harmonisation-E9 Guidelines in which missing values were substituted by the median in each group (primary analysis) and the loss was then calculated using actual data (secondary analysis). Secondary outcomes were ultrasound (US) time, cumulative dissipated energy (CDE), and percentage total equivalent power in position 3. Postoperative follow-up was at 3 months. The mean preoperative CDVA was 0.41 logMAR in the torsional group and 0.38 logMAR in the longitudinal group, improving to 0.07 logMAR postoperatively in both groups. The mean ECD loss was 7.2% ± 4.6% in the torsional group (72 patients) and 7.1% ± 4.4% in the longitudinal group (76 patients), with no statistically significant differences in the primary analysis (P = .342) or secondary analysis (P = .906). The mean US time, CDE, and percentage total equivalent power in position 3 were statistically significantly lower in the torsional group (98 patients) than in the longitudinal group (94 patients) (P<.001). The torsional mode was as safe as the longitudinal mode in phacoemulsification for age-related cataract.

Emulsification action of longitudinal and torsional ultrasound tips and the effect on treatment of the nucleus during phacoemulsification

To compare the results of emulsification of test materials when applying torsional and longitudinal emulsification tips as well as to define emulsification and determine how it occurs by examining the effect of phacoemulsification. Miyoshi Eye Hospital, Fukuyama, Japan. An ultra-high-speed digital video camera was used to record emulsification of chestnuts and human nuclei in a test chamber, simulating real phacoemulsification. The treatment of the nucleus as a result of phacoemulsification was analyzed visually. Visual comparison of video data showed that the test chamber materials were completely desiccated by the torsional phaco device. Longitudinal phacoemulsification resulted in cutting and coring of the test chamber materials, but not total disruption. Visual comparisons showed that complete obliteration and desiccation of the nucleus, or emulsification, occurs only with torsional phacoemulsification. These observations open the way to understanding the best approach to new tip design and surgical strategy development. Neither author has a financial or proprietary interest in any material or method mentioned.

Bead-flow pattern: Quantitation of fluid movement during torsional and longitudinal phacoemulsification

To develop a bead-flow pattern for visualizing and comparatively quantifying fluid movement using a torsional or longitudinal ultrasound (US) phaco handpiece. Magill Laser Center, Medical University of South Carolina, Charleston, South Carolina, USA. Visualization and quantification of intraocular fluid dynamics were evaluated by injecting neutrally buoyant, collagen-coated polystyrene beads (diameter, 125 to 212 microm) into the phacoemulsification irrigation flow. Using the anterior chamber of a cadaver or porcine eye or a laboratory test chamber, the bead-flow pattern was video recorded. Qualitative comparisons between longitudinal and torsional phacoemulsification were made using video-processing software to track the beads frame by frame. The time (quantitative) required to aspirate a bolus of beads from the anterior chamber (clearance time) was measured and compared between the 2 modalities. Aspiration efficiency was calculated to compare operating conditions in a test chamber using high-speed videography; conditions included irrigation/aspiration (I/A) only (0% power) and clinically relevant fluidic parameters and power modulations with torsional, longitudinal, or a combination of powers applied. Qualitative and quantitative analyses of the fluidic patterns of bead flow in the peripheral anterior chamber and near the aspirating tip opening indicated that torsional fluidics behave closer to the I/A-only configuration than longitudinal phacoemulsification, with the latter repelling more bead material in front of the aspiration tip. Bead clearance time was approximately 50% faster with torsional than with longitudinal US, regardless of the power setting. Bead flow-pattern evaluation is a feasible approach to future studies of fluid movement in the anterior chamber.

Comparison of Influences on the Cornea by the Longitudinal Phacoemulsification Between the Sovereign® and Infiniti®

Purpose: To compare the influences on the corneal endothelium and surgically induced astigmatism following cataract surgery performed with Sovereign and Infiniti using the longitudinal phacoemulsification through the clear corneal incision. Methods: Patients were operated on with the Sovereign (n=46) and Infiniti (n=45) programmed with the same parameters. Corneal thickness, endothelial cell count, effective phaco time and average phaco power were measured. Surgically induced astigmatism was calculated by keratometric readings. Results: The change in corneal thickness at 1 day and endothelial cell count at 1 month postoperatively was significantly lower in the Infiniti group. However, there were no significant differences in the change in corneal thickness and endothelial cell count at 2 months postoperatively. Surgically induced astigmatism in the 2 groups was consistently similar. Effective phaco time and average phaco power were lower in the Sovereign group. Conclusions: Using the longitudinal phacoemulsification, early postoperative change of corneal endothelium was lower in the Infiniti group. However, the efficacy of phacoemulsification in the Sovereign group was superior to the Infiniti group.

The Comparison between Torsional and Conventional Mode Phacoemulsification in Moderate and Hard Cataracts

PurposeTo compare the intraoperative performances and postoperative outcomes of cataract surgery performed with longitudinal phacoemulsification and torsional phacoemulsification in moderate and hard cataracts.MethodsOf 85 patients who had senile cataracts, 102 eyes were operated on using the Infiniti Vision System. Preoperative examinations (slit lamp examination, mean central corneal thickness, and central endothelial cell counts) were performed for each patient. Cataracts were subdivided into moderate and hard, according to the Lens Opacities Classification System III grading of nucleus opalescence (NO). Eyes in each cataract group were randomly assigned to conventional and torsional phaco-mode. Intraoperative parameters, including ultrasound time (UST), cumulative dissipated energy (CDE), and the balanced salt solution plus (BSSP) volume utilized were evaluated. Best corrected visual acuity (BCVA) was checked on postoperative day 30; mean central corneal thickness and central endothelial cell counts were investigated on postoperative days 7 and 30.ResultsPreoperative BCVA and mean grading of NO showed no difference in both groups. Preoperative endothelial cell count and central corneal thickness also showed no significant difference in both groups. In the moderate cataract group, the CDE, UST, and BSSP volume were significantly lower in the torsional mode than the longitudinal mode, but they did not show any difference in the hard cataract group. Torsional group showed less endothelial cell loss and central corneal thickening at postoperative day seven in moderate cataracts but showed no significant differences, as compared with the longitudinal group, by postoperative day 30.ConclusionsTorsional phacoemulsification showed superior efficiency for moderate cataracts, as compared with longitudinal phacoemulsification, in the early postoperative stage.

Comparison of Torsional and Microburst Longitudinal Phacoemulsification: A Prospective, Randomized, Masked Clinical Trial

To compare intraoperative performance and postoperative outcome of three phacoemulsification technologies in patients undergoing microcoaxial phacoemulsification through 2.2-mm corneal incisions. The prospective, randomized, single-masked study included 360 eyes randomly assigned to torsional (Infiniti Vision System; Alcon Laboratories, Fort Worth, TX), microburst with longitudinal (Infiniti), or microburst with longitudinal (Legacy Everest, Alcon Laboratories) ultrasound. Assessments included surgical clock time, fluid volume, and intraoperative complications, central corneal thickness on day 1 and months 1 and 3 postoperatively, and endothelial cell density at 3 months postoperatively. Comparisons among groups were conducted. Torsional ultrasound required significantly less surgical clock time and fluid volume than the other groups. There were no intraoperative complications. Change in central corneal thickness and endothelial cell loss was significantly lower in the torsional ultrasound group at all postoperative visits (P < .001, Kruskal-Wallis test) compared to microburst longitudinal ultrasound modalities. Torsional ultrasound demonstrated quantitatively superior intraoperative performance and showed less increase in corneal thickness and less endothelial cell loss compared to microburst longitudinal ultrasound.

Comparison of torsional and longitudinal modes using phacoemulsification parameters

To compare phacoemulsification parameters of torsional and longitudinal ultrasound modes. Ophthalmology Department, Military Health Service Institute, Warsaw, Poland. This prospective study evaluated eyes 1, 7, and 30 days after phacoemulsification with an Infiniti Vision System using the torsional or longitudinal ultrasound (US) mode. Cataract classification was according to the Lens Opacities Classification System II. Nucleus fragmentation was by the phaco-chop and quick-chop methods. Primary outcome measures were phaco time, mean phaco power, mean torsional amplitude, and aspiration time. Total energy, defined as cumulative dissipated energy (CDE) x aspiration time, and the effective coefficient, defined as aspiration time/phaco time, were also calculated. Four hundred eyes were evaluated. The CDE was statistically significantly lower in the torsional mode for nucleus grades I, II, and III (P<.001) but not for grade IV (P>.05). Aspiration time was statistically significantly shorter in the torsional mode than in the longitudinal mode for nucleus grades III and IV (P<.05). Total energy was significantly lower in the torsional mode for all nucleus densities (P<.05). The effective coefficient was significantly lower in the longitudinal mode except for nucleus grade I (P<.05). Torsional phacoemulsification was more effective than longitudinal phacoemulsification in the amount of applied fluid and the quantity of US energy expended. With the torsional method, it was possible to maintain a constant ratio of amount of fluid flow to quantity of US energy used, regardless of nucleus density.