Pathologic comparison of asymmetric or sulcus fixation of 3-piece intraocular lenses with square versus round anterior optic edges.

OBJECTIVE: To evaluate the pathologic findings of 3-piece intraocular lenses (IOLs) with asymmetric or sulcus fixation in pseudophakic cadaver eyes, comparing IOLs with square or round edges on the anterior optic surface. DESIGN: Comparative case series with pathology. PARTICIPANTS: A total of 661 pseudophakic cadaver eyes, obtained from eye banks within the United States, implanted with different IOLs. METHODS: Anterior segment scanning of whole eyes with a high-frequency ultrasound system or high-resolution anterior segment magnetic resonance imaging followed by gross examination. Selected eyes were processed for complete histopathologic analysis. MAIN OUTCOME MEASURES: Findings from imaging, gross, and histopathologic evaluation that could be related to out-of-the-bag fixation of the lenses. RESULTS: Of 661 pseudophakic cadaver eyes obtained, 13 had 3-piece hydrophobic acrylic IOLs with anterior and posterior square optic edges, and 14 had 3-piece lenses with anterior round edges (13 silicone lenses and 1 hydrophobic acrylic lens) without symmetric in-the-bag fixation. These 27 selected eyes were processed for complete histopathologic analysis. Gross findings in both groups were composed of IOL decentration and tilt, pigmentary dispersion within the anterior segment and on the IOL surface, and iris transillumination defects. Histopathology of the 14 eyes with 3-piece IOLs with round anterior optic edges showed mild focal disruption of the iris pigmented layer and loop protrusion/erosion in the ciliary sulcus. Additional changes observed in the 13 eyes with square anterior optic edge IOLs included iris changes, such as vacuolization, disruption and loss of the pigmented epithelial layers, iris thinning and atrophy, synechiae, and pigmentary dispersion within the trabecular meshwork. One eye also exhibited initial signs of optic nerve disc cupping. CONCLUSIONS: In this series, pathologic findings were more severe in eyes implanted with 3-piece IOLs with square anterior optic edges, suggesting that IOLs with round anterior edges are more suitable for sulcus fixation. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references.

Pathologic assessment of complications with asymmetric or sulcus fixation of square-edged hydrophobic acrylic intraocular lenses.

OBJECTIVE: One-piece hydrophobic acrylic intraocular lenses (IOLs) are not indicated for sulcus fixation because of complications, such as uveitis-glaucoma-hyphema syndrome. Similar complications may also be observed with 3-piece lenses that have a square optic edge on the anterior surface. The objective of this study was to provide pathologic evidence of complications related to out-of-the-bag fixation of 1- or 3-piece hydrophobic acrylic IOLs with anterior and posterior square optic edges. DESIGN: Comparative case series with pathology. PARTICIPANTS: A total of 661 pseudophakic cadaver eyes obtained from eye banks within the United States, implanted with different IOLs. METHODS: Anterior segment scanning of whole eyes with a high-frequency ultrasound system or high-resolution anterior segment magnetic resonance imaging, followed by gross examination. Selected eyes were processed for complete histopathologic analysis; some of them were explanted before histopathology to allow for direct light microscopic evaluation of the lenses. MAIN OUTCOME MEASURES: Findings from imaging, gross, and histopathologic evaluation that could be related to out-of-the-bag fixation of the lenses. RESULTS: A total of 256 eyes were implanted with hydrophobic acrylic IOLs with anterior and posterior square optic edges; 18 of them exhibiting asymmetric or sulcus IOL fixation (six 1-piece and twelve 3-piece IOLs) underwent complete histopathologic evaluation and were compared with the contralateral eyes with symmetric in-the-bag IOL implantation. Pathologic findings were composed of IOL decentration and tilt, pigmentary dispersion within the anterior segment and on the IOL surface, iris transillumination defects, iris changes including vacuolization/disruption/loss of the pigmented layer, iris thinning, and iris atrophy, as well as synechiae and loop erosion in the case of 3-piece lenses. Findings were more significant in comparison with the control contralateral eyes and were particularly evident in relation to the sulcus-fixated haptic in the case of 1-piece lenses. The majority of the eyes with 3-piece lenses showed signs of complicated surgery. CONCLUSIONS: This study provides pathologic correlation of complications that were clinically reported in the peer-reviewed literature in relation to sulcus fixation of 1-piece hydrophobic acrylic IOLs. The eyes with 3-piece lenses generally exhibited evidence of complicated surgery; therefore, all pathologic findings in those cases may not be strictly attributed to the out-of-the-bag fixation.

Determining optimal ultrasound off time with micropulse longitudinal phacoemulsification.

PURPOSE: To evaluate the optimum off time for the most efficient removal of lens fragments using micropulse ultrasound (US). SETTING: John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA. DESIGN: Experimental study. METHODS: Porcine lens nuclei were soaked in formalin for 2 hours and then cut into 2.0 mm cubes using the Signature US machine with a bent 0.9 mm phaco tip with a 30-degree bevel. The on time was 7 milliseconds (ms), and the off time was varied from 2 to 20 ms in 2 ms steps. Phacoemulsification efficiency (time for fragment removal) and chatter (number of times the fragment bounced from the tip) were measured. RESULTS: A nonsignificant linear increase in efficiency was observed with 2 to 6 ms of off time (R(2) = .87, P = .24). A significant linear decrease in efficiency was observed with 6 to 20 ms (R(2) = .74, P = .006). CONCLUSIONS: With micropulse longitudinal US, 6 to 7 ms of off time was as efficient as shorter off times; longer off times (8 to 20 ms) showed decreased efficiency. Chatter was minimal and statistically similar throughout. To maximize phacoemulsification US efficiency, an off-time setting of 6 ms is recommended. 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.

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.