Brian Zaugg

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

Purpose To validate a porcine lens model by comparing density and ultrasound (US) with known human standards using the Infiniti Ozil with Intelligent Phacoemulsification (torsional), Whitestar Signature Micropulse (longitudinal), and Ellips FX (transversal) modalities. Setting Department of Ophthalmology and Visual Sciences, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. Design Experimental study. Methods Lens nuclei were formalin soaked in hour‐based intervals and divided into 2.0 mm cubes. Density was characterized by crushing experiments and compared with known human measures. Efficiency and chatter were examined. Results The mean weight to cut thickness in half ranged from 16.9 g ± 5.5 (SD) in the 0‐hour group to 121.3 ± 47.5 gm in the 4‐hour group. Lenses in the 2‐hour group (mean 70.2 ± 19.1 g) best matched human density (P=.215). The mean efficiency ranged from 0.432 ± 0.178 seconds to 9.111 ± 2.925 seconds; chatter ranged from zero to 1.85 ± 1.927 bounces. No significant difference was detected when comparing the 2‐hour formalin group with human lenses in torsional and transversal US. There was no significant difference between transversal and torsional modalities, consistent with human studies. Although longitudinal (6 milliseconds on, 12 milliseconds off) was significantly more efficient at 50% power than at 25%, there was no significant difference compared with transversal or torsional US. Conclusions Animal lenses soaked for 2 hours in formalin were most comparable to human lenses. Longitudinal US may be an acceptable alternative to torsional and transversal US. Financial Disclosure Dr. Olson has been a consultant to Abbott Medical Optics, Inc., Becton, Dickinson and Co., and Allergan, Inc., and received grant support from Abbott Medical Optics, Inc. and Allergan, Inc. No author has a financial or proprietary interest in any material or method mentioned.

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

PURPOSE: To compare efficiency and chatter of Infiniti Ozil with and without Intelligent Phacoemulsification (IP) and the Signature Ellips with and without FX. SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Brunescent 2.0 mm human lens cubes were created by an instrument devised for this study. Cubes were tested (10 per test) for time of particle removal (efficiency) and for the number of times the lens particle bounced off the tip (chatter) at 300 mm Hg and 550 mm Hg, 50% and 100% power, and 50% and 100% amplitudes (amplitude for Ozil only). RESULTS: Of the ultrasound settings, efficiency varied from a mean of 3.3 seconds ± 1.4 (SD) to 50.4 ± 11.7 seconds and chatter from 0.0 to 52.0 ± 16.7 bounces per run. The Ozil‐IP was generally more efficient than the Ozil and the Ellips FX more efficient than the Ellips. At optimized values, the Ozil‐IP and Ellips‐FX were similar. In general, efficiency and chatter were better at 550 mm Hg and at 50% power. The amplitude effect was complex. Efficiency closely correlated with chatter (Pearson r2 = .31, P<.0001). CONCLUSIONS: Objective comparison of phacoemulsification efficiency and chatter found that optimized Ozil‐IP and Ellips‐FX were similar in both parameters and in general, both performed better than preceding technology. The study parameters can significantly affect efficiency and chatter, which strongly correlate with each other. Financial Disclosure: Dr. Olson has been a consultant to Abbott Medical Optics, Inc., Becton, Dickinson and Co., and Allergan, Inc., and has received grant support from Abbott Medical Optics, Inc., and Allergan, Inc. No author has a financial or proprietary interest in any material or method mentioned.

In-the-Bag Capsular Tension Ring and Intraocular Lens Subluxation or Dislocation: A Series of 23 Cases

OBJECTIVE To describe clinical and pathologic findings from cases of in-the-bag capsular tension ring (CTR) and intraocular lens (IOL) subluxation or dislocation. DESIGN Retrospective case series with clinicopathologic correlation. PARTICIPANTS Twenty-three explanted subluxated/dislocated capsular bags containing a CTR and an IOL explanted in Europe and submitted in fixative to the Berlin Eye Research Institute. METHODS Standard gross and light microscopy of specimens, complete histopathologic analyses of selected specimens done at the University of Utah, as well as questionnaire sent to explanting surgeons, and patient chart review, when available. MAIN OUTCOME MEASURES Lens design, material, and abnormalities, capsular bag anomalies, patient demographic data, surgical dates, and presence or absence of known risk factors. RESULTS Patients were aged 76.31 ± 8.24 years at explantation, which was performed 81.5 ± 32.2 months after implantation. The IOLs in these cases were 3-piece hydrophobic acrylic (N = 11), 1-piece hydrophobic acrylic (n = 6), 3-piece silicone (n = 4), or 1-piece hydrophilic acrylic (n = 2) designs; all CTRs were made of poly(methyl methacrylate). Available information on associated ocular conditions included pseudoexfoliation (n = 17), glaucoma (n = 4), vitrectomy/retina surgery (n = 3), and trauma (n = 1). Complete histopathologic assessment in 3 specimens showed signs consistent with pseudoexfoliation, without available history related to this condition in one of the cases. Moderate/severe degrees of Soemmerings ring formation and capsulorhexis phimosis were observed or reported in 13 and 11 specimens, respectively. Fourteen eyes were implanted and explanted by the same surgeon, with an interval of 92.7 ± 23.4 months between the procedures. His rate of explantation because of subluxation/dislocation was 0.76% of the CTRs implanted during the time considered. CONCLUSIONS Explantation because of postoperative subluxation or dislocation of CTR-IOL-capsular bag complexes occurred approximately 6.8 years after implantation in this series, providing further evidence that a fine line exists between zonular insufficiency that can be stabilized with the CTR alone and that requiring further support. Analyses of large series may help to define common factors associated with this complication, as well as surgical planning and employment of various endocapsular support devices to enhance postoperative zonular stabilization.

Optimum on-time duty cycle for micropulse technology

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

Pathology of 219 human cadaver eyes with 1-piece or 3-piece hydrophobic acrylic intraocular lenses: Capsular bag opacification and sites of square-edged barrier breach

PURPOSE: To assess capsular bag opacification and sites of initial posterior capsule opacification (PCO) in human cadaver eyes with square‐edged 1‐piece or 3‐piece hydrophobic acrylic intraocular lenses (IOLs). SETTING: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Eyes were immersed in 10% formalin after enucleation and had anterior segment scanning with very‐high‐frequency ultrasound (Artemis). After the eyes were sectioned at the equator, gross examination of the anterior segment was performed from the posterior aspect to assess capsular bag opacification, anterior capsule coverage of the IOL edge, and IOL fixation. Selected eyes had histopathologic examination. RESULTS: One hundred nineteen eyes with 1‐piece IOLs and 100 with 3‐piece IOLs were included in the analyses of capsular bag opacification. There was no difference in central (P=.29) or peripheral (P=.76) PCO. In 63 of 84 eyes with a 1‐piece IOL and peripheral PCO, the optic–haptic junction was the site of initiation. In eyes with a 3‐piece IOL, initial peripheral PCO was observed at nearly the same rate whether there was full 360‐degree anterior capsulorhexis overlap of the optic or no overlap (P=.13). In the latter, the site of PCO initiation was in areas lacking capsulorhexis coverage in 46% of eyes. CONCLUSIONS: There was no difference in central or peripheral PCO between 1‐piece and 3‐piece hydrophobic acrylic IOLs. With 1‐piece IOLs, PCO tended to start at the optic–haptic junctions. With 3‐piece IOLs, full anterior capsule coverage did not produce a statistically significant benefit with respect to PCO prevention. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Phacoemulsification efficiency with a radiused phaco tip

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

Determining Optimal Torsional Ultrasound Power for Cataract Surgery With Automatic Longitudinal Pulses at Maximum Vacuum Ex Vivo

PURPOSE To determine the optimal longitudinal power settings for Infiniti OZil Intelligent Phaco (IP) at varying torsional amplitude settings; and to test the hypothesis that increasing longitudinal power is more important at lower torsional amplitudes to achieve efficient phacoemulsification. DESIGN Laboratory investigation. METHODS setting: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah. procedure: Individual porcine nuclei were fixed in formalin, then cut into 2.0 mm cubes. Lens cube phacoemulsification was done using OZil IP at 60%, 80%, and 100% torsional amplitude with 0%, 10%, 20%, 30%, 50%, 75%, or 100% longitudinal power. All experiments were done using a 20 gauge 0.9 mm bent reverse bevel phaco tip at constant vacuum (550 mm Hg), aspiration rate (40 mL/min), and bottle height (50 cm). main outcome measure: Complete lens particle phacoemulsification (efficiency). RESULTS Linear regression analysis showed a significant increase in efficiency with increasing longitudinal power at 60% torsional amplitude (R(2) = 0.7269, P = .01) and 80% torsional amplitude (R(2) = 0.6995, P = .02) but not at 100% amplitude (R(2) = 0.3053, P = .2). Baseline comparison of 60% or 80% vs 100% torsional amplitude without longitudinal power showed increased efficiency at 100% (P = .0004). Increasing longitudinal power to 20% abolished the efficiency difference between 80% vs 100% amplitudes. In contrast, 75% longitudinal power abolished the efficiency difference between 60% vs 100% torsional amplitudes. CONCLUSIONS Results suggest that longitudinal power becomes more critical at increasing phacoemulsification efficiencies at torsional amplitudes less than 100%. Increasing longitudinal power does not further increase efficiency at maximal torsional amplitudes.

Clinicopathologic correlation of capsulorhexis phimosis with anterior flexing of single-piece hydrophilic acrylic intraocular lens haptics.

UNLABELLED We describe 2 cases in which patients with 4-looped single-piece hydrophilic acrylic intraocular lenses (IOLs) exhibited postoperative complications including capsulorhexis phimosis, decentration, tilt, hyperopic shift, and luxation leading to explantation of the IOL-capsular bag complex. The excessive capsule fibrosis led to anterior flexing of the IOL haptics in both cases, even in the presence of a capsular tension ring (CTR). Histopathological analyses revealed a thick fibrocellular tissue attached to the inner surface of the anterior capsules, corresponding to the anterior capsule opacification and folds. An amorphous substance was observed on the outer surface of the anterior capsule in the case with a CTR, suggesting pseudoexfoliation material. These and similar cases raise concerns about the postoperative behavior of highly flexible IOLs in the presence of excessive capsular bag fibrosis. FINANCIAL DISCLOSURE No author has a financial or proprietary interest in any material or method mentioned.

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

Purpose To determine the optimum power settings in micropulsed ultrasound (US). Setting John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA. Design Experimental study. Methods Pig lenses hardened to be comparable to dense human cataracts were cut into 2.0 mm cubes and removed using micropulsed longitudinal US with previously optimized settings (6 milliseconds on and 6 milliseconds off and using a 0.9 mm 30‐degree beveled bent phaco tip). The aspiration was set at 40 mL/min and the vacuum level at 550 mm Hg. Twenty lens cubes were tested with the power set from 10% to 100% in increments of 10%. Primary outcome measures were efficiency time (time to lens removal) and chatter (number of times the lens fragment visibly bounced off the tip). Results Efficiency time decreased with increasing power. There was a correlation between power and efficiency time (R2 = 0.41, P = .046), which was more substantial between 30% and 100% power (R2 = 0.71, P = .004). The mean number of chatter events did not differ significantly between power settings (R2 = 0.012, P = .1195). Conclusions There was a 5‐fold increase in efficiency between 10% power and 20% power, which likely indicates that there is a minimum power threshold for efficient breakup of the lens. Between 20% and 100% power, there was a linear, strong, and statistically significant improvement in efficiency in these lens fragments. In addition, with micropulsed US there was little chatter or microchatter throughout the power range. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Pathology of 157 human cadaver eyes with round-edged or modern square-edged silicone intraocular lenses: Analyses of capsule bag opacification

PURPOSE: To assess the degree of capsular bag opacification in human cadaver eyes with silicone intraocular lenses (IOLs), specifically comparing the differences between round‐edged IOLs and modern square‐edged IOLs. SETTING: John A. Moran Eye Center, University of Utah, USA. DESIGN: Experimental study. METHODS: The eyes were immersed in 10% formalin on enucleation. They had anterior segment scanning with a very‐high‐frequency ultrasound (Artemis). After the eyes were sectioned at the equator, gross examination of the anterior segment was performed from the posterior aspect to assess the degree of capsular bag opacification, coverage of the IOL edge by the anterior capsule, and IOL fixation. Selected eyes also had histopathologic examination. RESULTS: Eighty‐seven eyes with a 3‐piece round‐edged IOL, 43 with a 3‐piece square‐edged IOL, 26 with a 1‐piece plate IOL, and 1 with an accommodating IOL design were included in the analyses of capsular bag opacification. Comparison between 3‐piece round‐edged IOLs and square‐edged IOLs showed statistically significant differences in central posterior capsule opacification (PCO) (P=.0001687) and peripheral PCO (P<.0001). In eyes with square‐edged IOLs, PCO had a tendency to start in areas without capsulorhexis coverage of the optic. Twenty‐one of 26 eyes with a silicone plate IOL had a neodymium:YAG posterior capsulotomy for dense PCO. CONCLUSIONS: This first study using pseudophakic human cadaver eyes that includes a significant number of modern 3‐piece silicone IOLs with square optic edges confirmed the role of this design in the prevention of PCO. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.