Phacoemulsification Efficiency Research Articles

A comparison of venturi and peristaltic based phacoemulsification efficiency in routine femtosecond laser cataract surgery

OBJECTIVETo compare the efficiency of venturi and peristaltic pump phacoemulsification systems in patients undergoing routine laser cataract surgery. DESIGNSingle center, non-randomized clinical study. PARTICIPANTSThe study compared consecutive eyes with moderate nuclear sclerosis undergoing routine laser cataract surgery at the Outpatient Eye Center, Mercy Health System, Springfield, MO, USA. METHODSEach surgery utilized the same femtosecond laser settings. Surgeries were performed with either a venturi or peristaltic vacuum system by a single surgeon (WJS). The EFX, percent power, ultrasound time (UST), the total time that the phaco tip was in the eye (phaco tip in/out time, PIOT) and the surgery time (speculum in/out time) were recorded. Exclusions and intraoperative complications were also analyzed. RESULTS995 eyes were included in the study. The EFX in the venturi eyes (1.7±1.3; n=521) compared to peristaltic eyes (2.1±1.4; n=474) was lower (p <0.0001). Similarly, the UST in the eyes performed with the venturi system versus the peristaltic system was reduced (32.4±22.3 sec vs. 40.7± 25.7 sec; p <0.0001). The PIOT in the venturi group compared to the peristaltic group was less (71.1±31.1 sec vs. 79.1±36.1 sec; p = 0.0002). The case time (speculum in/out time) was lower for the venturi eyes (307.2±68.8 sec vs. 311.6±53.6 sec; p=0.268). CONCLUSIONIn eyes undergoing routine laser cataract surgery, use of the venturi pump system was more efficient compared to peristaltic pump system based on energy use and time, and there was no significant difference in complications.

Efficiency and Safety of Binocular Cataract Phacoemulsification

A literature review is presented on the comparative assessment of two options for conducting cataract phacoemulsification — monocular phacoemulsification of cataract, (delayed sequential bilateral cataract surgery, DSBCS) and binocular phacoemulsification of cataract (immediate sequential bilateral cataract surgery, ISBCS). It has been established that to date in the literature there is a sufficient amount of data indicating the positive aspects of ISBCS, associated with faster rehabilitation, better functional results, as well as time, financial, and economic aspects. The safety of ISBCS is determined by the minimum likelihood of postoperative bilateral endophthalmitis with careful selection of patients, the required surgeon qualifications and strict adherence to the surgical protocol. Comparatively, in accordance with the results obtained, postoperative refractive indices, the value of the maximum corrected distance visual acuity, the frequency of complications and the degree of patient satisfaction were the same regardless of whether the bilateral cataract surgery was performed simultaneously or sequentially. The effectiveness of ISBCS is determined by quick rehabilitation, the need for only one pair of glasses, a decrease in visits to the clinic, the absence of anisometropia between operations, as well as only one general anesthesia (if necessary). The experience of clinics where such procedures were carried out shows that after ISBCS, minor refractive errors occur, while they are almost always symmetrical, characterized by a slight deviation from the target refraction and rapid recovery of binocular and stereoscopic vision. In financial terms, in accordance with the calculations carried out, the cost of DSBCS in various countries may be higher than the cost of ISBCS by 10.8–47.9 %. In absolute terms, simultaneous cataract surgery on two eyes (Finland) saved €449 per patient in medical costs and €739 after travel and home care costs were included. Taking into account the cost of lost work time, the savings were €849 per patient. The wider distribution of ISBCS is associated with the approval of the ophthalmological community and insurance companies, as well as the development of standardized teaching materials for practicing ophthalmologists.

Optimizing Tip Diameter in Phacoemulsification of Varying Lens Sizes: An in vitro Study.

PurposeWe assessed the effect of two lens cube sizes, three tip sizes, and two ultrasound (US) approaches on phacoemulsification efficiency and chatter.MethodsAfter porcine lens nuclei were soaked in formalin, we divided them into cubes measuring 2.0 mm or 3.0 mm. We collected efficiency and chatter data for 30-degree bent 19 G, 20 G, and 21 G tips with a continuous torsional US system; and for straight 19 G, 20 G, and 21 G tips with a micropulse longitudinal US system.ResultsThe average time needed for removal was always higher for the 3.0 mm lens cube than for the 2.0 mm lens cube. Statistically significant differences were observed between the 19 G and 21 G tips with micropulse longitudinal US using a 2.0 mm cube and a 3.0 mm cube, and with continuous transversal US using a 2.0 mm lens cube and a 3.0 mm cube. We did not observe significant differences between 19 G and 20 G tips with either cube size in either US system. However, we noted identical trends for both cube sizes with both US approaches; 19 G tips performed better than 20 G and 21 G tips.ConclusionRegardless of the lens size, 19 G needles were the most efficient, and had both the fewest outliers and the smallest standard deviations.

Prevention method of toric intraocular lens rotation after phacoemulsification of cataract using a standard capsule ring

At the same time, phacoemulsification of cataracts remains the most popular surgery. But the problem among phacosurgeons is the correction of existing corneal astigmatism. According to studies, about 30% of the world's population have corneal astigmatism with a strength of 0.75D and above, which leads to a decrease in visual acuity after phacoemulsification of cataracts in the absence of its correction.The most commonly used method to correct corneal astigmatism is the implantation of toric intraocular lenses (TIOL). The main condition for obtaining high visual acuity after TIOL implantation is the location of the astigmatic component of the artificial lens in accordance with the strong meridian of the cornea. The aim of this study was to evaluate the effectiveness of the proposed method of preventing the toric intraocular lens rotation after phacoemulsification of cataracts in the eyes with corneal astigmatism by implantation of a standart capsule ring.Material and methods. The article presents the results of a comprehensive examination of 43 patients (59 eyes) who underwent surgery by phacoemulsification of cataracts with implantation of toric IOL to correct concomitant corneal astigmatism. Corneal astigmatism according to keratometry ranged from 0.5D to 4.25D (average 1.96 ± 0.1 D). Patients were divided into 2 groups. The first group consisted of 26 patients (31 eyes). Patients in this group underwent phacoemulsification with toric IOL implantation according to standard techniques without the use of techniques that prevent rotation of the artificial lens in the postoperative period. The second group included 18 patients (28 eyes) who were operated on according to our proposed prevention method of TIOL rotation. As a result of the study, it was found that rotation of TIOL was detected 6 months after surgery in the I group without the use of developed method in 22 eyes (70.9%), in the II group, where the capsule ring was implanted, rotation occurred in 12 eyes (42.85%). In the II group in all cases, the deviation of the TIOL axis did not exceed 6 degrees. The proposed method of prevention of rotation of TIOL allows to increase the efficiency of phacoemulsification of cataracts.Conclusions. Developed a method of preventing the rotation of the toric intraocular lens using a standard capsule ring, which is implanted and located on top of the haptic support elements of the artificial lens can increase the efficiency of phacoemulsification of cataracts in the eyes with corneal astigmatism, contributes to the rotational stability of the toric lens and provides long-term results of visual functions, reduces the need for repeated surgery due to reposition of the rotated lens and can be recommended for implementation in the practice of ophthalmic surgeons.The use of implantation of a standard capsule ring according to the proposed in this study method prevents the rotation of the toric intraocular lens by more than 6 degrees in all cases, which does not significantly reduce visual acuity and does not require reposition of the artificial lens. This method of preventing rotation of the toric intraocular lens allows to achieve visual acuity of 0.7 and above in 85.6% of cases.

Comparative study of conventional versus torsional phacoemulsification in management of hard nucleus

Background Phacoemulsification acoenergy and shortening the phacotime can decrease this risk. Aim The aim of this work is to compare the safety and the efficiency of phacoemulsification using conventional and torsional ultrasound modalities for hard nucleus cataracts. Settings and design This was a prospective randomized interventional study. Patients and methods A total of 30 eyes of 29 patients having hard nuclear cataract (grades IV and V) were divided into two groups. Group A included 15 eyes whose cataract was operated on by conventional phacoemulsification using the Infiniti machine. Group B included 15 eyes whose cataract was operated on by torsional phacoemulsification using the OZil technology of the Infiniti machine. Intraoperative ultrasound time and cumulative dissipated energy were recorded. Postoperative central corneal thickness (CCT) was measured at days 1, 7, and 30, and specular microscopy was done at 1 month. Statistical analysis The collected data were coded, tabulated, and statistically analyzed. Results The mean ultrasound time and cumulative dissipated energy and the amount of irrigating fluid were significantly higher in group A. There was a highly significant decrease in endothelial cell count (ECC) in both groups. ECC was significantly lower in the conventional group than in the torsional group at 1 month postoperatively. CCT in both groups was significantly increased at day 1 and then decreased at 1 week and 1 month but was still significantly higher than the preoperative level. CCT became higher in the conventional group than in the torsional group at all follow-up times, but this was significant only at day 1 and week 1 and not significant at 1 month. Conclusion Both ultrasound modalities can be used in hard nucleus phacoemulsification. However, the torsional ultrasound proved to be safer. The choice between these technologies is of particular importance when operating eyes with low ECC.

Effects on phacoemulsification efficiency and chatter at variable longitudinal ultrasound settings when combined with constant torsional energy.

To evaluate longitudinal power settings for optimally efficient lens fragment removal, using the Centurion machine. John A. Moran Eye Center, University of Utah, Salt Lake City, USA. Experimental study. Porcine lens nuclei were cut into 2.0 mm cubes. Experiments were conducted at 100% torsional power; vacuum set at 500 mm Hg, aspiration 50 mL/min, and intraocular pressure 110 mm Hg. A 20-degree tip with a 30-degree bevel was used. Longitudinal power was tested between 20% and 100%. Efficiency (time for fragment removal) and chatter (the number of times the fragment bounced from the tip) were measured. A linear increase in efficiency was observed from 20% to 100% longitudinal power (R = 0.9281, slope = -0.0271). An efficiency slope change occurred at 60% power, with the largest incremental change in efficiency between 20% and 60% (R = 0.9756, slope = -0.0394) and a lesser change between 60% and 100% (R = 0.9827, slope = -0.0121). Chatter analysis showed minimal events at 20% to 60%, but a significant increase at >80% (P = .005). This increase appeared to be incremental (R = 0.8929). Increasing longitudinal power, with all other settings constant, increased efficiency. Greatest efficiency gains were observed between 20% and 60%. At 80% and 100%, chatter events increased significantly. With a goal of recommending optimally efficient settings while minimizing excess energy and chatter, adding 60% of longitudinal power to 100% torsional power was shown to be the best setting to increase efficiency and avoid repulsion in these vacuum and aspiration settings.

Clinical Outcomes of Steep-Axis One-Handed Phacoemulsification under the Guidance of a Verion Image-Guided System.

Purpose To compare the efficiency and safety of steep-axis one-handed phacoemulsification with steep-axis two-handed phacoemulsification. Patients and Methods Patients with cataracts underwent steep-axis one-handed (steep-axis one-handed group) or steep-axis two-handed (steep-axis two-handed group) phacoemulsification with a 2.4 mm clear corneal incision (CCI) under the guidance of the Verion Image-Guided System. Intraoperative phacoparameters, such as visual acuity, surgically induced astigmatism (SIA), total corneal astigmatism (TCA), angle of error (AE), corneal volume (CV), and corneal endothelial cells, were compared. Results There were no significant differences in the intraoperative phacoparameters between the two groups. The visual outcomes were significantly better in the steep-axis one-handed group than in the two-handed group at 1 week postoperatively (all p < 0.05) but not at 1 month and 3 months postoperatively. TCAs were significantly decreased in both groups at 1 and 3 months postoperatively (all p < 0.05). There were no significant differences at any follow-up points in both groups (all p < 0.001). At 3 months postoperatively, the SIA was 0.95 ± 0.44 D in the steep-axis one-handed group and 1.01 ± 0.50 D in the steep-axis two-handed group; there was no significant difference between the groups. The AE was 39.45 ± 26.53° in the steep-axis one-handed group and 49.75° ± 26.23° in the steep-axis two-handed group, which were significantly different (p=0.005). Endothelial cell loss was significantly lower in the steep-axis one-handed group than that in the steep-axis two-handed group at all follow-up points (all p < 0.05). Conclusions Both the steep-axis one-handed and the steep-axis two-handed techniques could significantly decrease TCA. Compared with the steep-axis two-handed technique, the steep-axis one-handed technique has the advantage of decreasing the AE and reducing trauma to the cornea in soft-to-moderate nuclei.

Visual Outcomes and Intraoperative Complication Rates of Phacoemulsification Cataract Surgery by Third Year Ophthalmology Residents in the UP-Philippine General Hospital

Background. Phacoemulsification is the most important cataract surgical procedure performed by ophthalmology residents. There is an increasing and consistent trend in international studies on decreased complication rates and more efficient surgical techniques with more surgeries performed. The data collected from this study can be used to quantitatively assess the cataract surgery training of Ophthalmology residents in the country and can help to improve the quality of cataract surgeries taught and performed in the training programs.&#x0D; Objectives. To analyze outcomes of phacoemulsification cataract surgeries and to determine the intraoperative complication rates of third-year residents of the University of the Philippines - Philippine General Hospital (UP-PGH).&#x0D; Methods. Retrospective chart review of phacoemulsification cases done by eight third-year ophthalmology residents at the UP-PGH from January 1 to December 31, 2017. Outcomes measured included postoperative best corrected visual acuity (BCVA), intraoperative complications (posterior capsular rent and vitreous loss), and adjusted phacoemulsification times (total phacoemulsification time multiplied by phacoemulsification power used).&#x0D; Results. Four hundred ninety-two (492) cases were analyzed. Postoperative mean BCVA was 20/25. There were no significant differences in visual acuity outcomes over the course of training. Intraoperative complications occurred in 33 cases, with fewer cases with posterior capsule rent and vitreous loss later in training after the first 50 cases. There was a downward trend of adjusted phacoemulsification time throughout training, with a significant difference between the first 50 and 100 cases.&#x0D; Conclusion. Good visual outcomes are achievable throughout the resident’s phacoemulsification learning curve. Surgical competency in phacoemulsification, as measured by complication rates and phacoemulsification efficiency, still improves significantly with an increasing number of cases and experience beyond the first 100 cases.

Impact of torsional micropulse on phacoemulsification efficiency and chatter

ObjectiveEvaluate the effect of increasing ultrasound (US) power on chatter events and efficiency under both continuous and micropulse torsional US to reduce total cataract extraction times. DesignIn vitro laboratory study. MethodsPorcine lens nuclei were incubated in formalin for 2 hours and then cut into 2-mm cubes. Phacoemulsification was performed using the Centurion Vision System and Infiniti OZil handpiece with the balanced tip. Both US modalities were studied at 60%, 80%, and 100% power. Micropulse rate was 83 pulses per second with 50% on time. Each combination comprised 20 runs. Efficiency was considered as the total time for a cube to be emulsified; chatter was the number of times the lens fragment bounced off the tip. ResultsThere was significant decrease in efficiency when power was increased from 60% to 100% (1.33–1.97 s; p < 0.001) under micropulse US and significant increase in chatter when power was further increased to 100% from 60% (0.15–0.94 s; p < 0.001). There was no significant efficiency change with increased power under continuous US. Comparing the phacoemulsification efficiency between continuous and micropulse US, we found no significant difference at 60% and 80% power; at 100% power, continuous was significantly more efficient than micropulse (1.48 and 1.97 s, respectively; p = 0.001). ConclusionsIncreasing power above 60% decreased efficiency under torsional micropulse US. We believe that this was due to the chatter increase observed with increasing US power. Torsional continuous US was significantly more efficient than micropulse US at 100% power.

Microinterventional endocapsular nucleus disassembly: novel technique and results of first-in-human randomised controlled study

AimTo assess the safety and efficacy of microinterventional endocapsular nuclear fragmentation in moderate to severe cataracts.MethodsThis was a prospective single-masked multisurgeon interventional randomised controlled trial (ClinicalTrials.gov NCT02843594) where 101 eyes...

Effect of high vacuum and aspiration on phacoemulsification efficiency and chatter using a transversal ultrasound machine

To examine the role of high vacuum and aspiration settings on efficiency using a transversal ultrasound (US) machine. John A. Moran Eye Center Laboratory, University of Utah, Salt Lake City, Utah, USA. Experimental study. Porcine lens nuclei were incubated in formalin for 2hours and then cut into 2.0mm cubes. Phacoemulsification was performed using the Whitestar Signature machine. Settings were bottle height 50cm, on-time 6milliseconds, and off-time 6milliseconds. One hundred percent power was used for all 240 runs. Tested parameters were aspiration of 50mL/min and 60mL/min and vacuum of 500, mm Hg, 600mm Hg, and 650mm Hg. With continuous US, increasing aspiration from 50mL/min to 60mL/min significantly increased efficiency (23%). Increasing vacuum from 500mm Hg to 650mm Hg and from 600mm Hg to 650mm Hg significantly increased efficiency (20.2% and 13.6%, respectively). Higher vacuum and aspiration parameters did not influence the incidence of chatter events. In the micropulse US group, there was no significant efficiency increase with increasing vacuum or aspiration levels. There was a significant efficiency increase of continuous over micropulse US at an aspiration setting of 60mL/min and vacuum settings of 600mm Hg and 650mm Hg. As aspiration and vacuum increased, efficiency increased under continuous transverse US. No significant efficiency improvement occurred at high aspiration and vacuum settings under micropulse US. At 60mL/min aspiration and more than 600mm Hg vacuum, continuous power was significantly more efficient than micropulse transverse US.

Optimum on-time duty cycle for a transversal ultrasound machine

To evaluate the optimum on-time setting for the most efficient removal of lens fragments using micropulse ultrasound (US) and Ellips FX transversal US in the Whitestar Signature Pro phacoemulsification machine. John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA. Experimental study. Porcine lens nuclei were soaked in formalin for 2hours and cut into 2.0mm cubes. The US machine was used with a bent 0.9mm phaco tip and a 30-degree bevel. The off time was set to 6milliseconds (ms) and the on time varied from 4 to 10ms in 1ms increments. Efficiency (time for fragment removal) and chatter (number of times the fragment bounced from the tip) were measured. A linear incremental increase in efficiency was observed between 4ms and 6ms. The most statistically significant efficiency was achieved with an on time of 6ms. On times shorter than 6ms were significantly less efficient (P=.05). Greater on times (7 to 10ms) did not result in a significant difference in efficiency (P=.72), but did appear to have more chatter events when comparing on-time settings of 7 to 10ms with 4 to 6ms (P=.02). With micropulse transversal US, 6ms of on time was as efficient as longer on times. To maximize phacoemulsification efficiency and minimize chatter events, an on time of 6ms is recommended.

High vacuum and aspiration on phacoemulsification efficiency and chatter for Centurion

ObjectiveTo compare relative efficiency and chatter of high aspiration and vacuum settings. DesignIn vitro laboratory study. MethodsThe John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, was the study setting. Porcine nuclei were fixed in formalin and cut into 2.0 mm cubes. Lens cubes were phacoemulsified with Balanced tips at 50 and 60 mL/min aspiration with 500, 600, and 700 mm Hg vacuum with monitored forced infusion. Experiments were conducted at constant torsional power, longitudinal power, and intraocular pressure. ResultsNo significant change was observed in average chatter across each tested setting. Increasing aspiration rate did not increase efficiency. Increasing vacuum up to 600 mm Hg from 500 mm Hg did not change efficiency. However, increasing vacuum to 700 mm Hg decreased efficiency (p = 0.008 for 500 mm Hg vs 700 mm Hg and p = 0.05 for 600 mm Hg vs 700 mm Hg). Increasing aspiration and increasing vacuum did not significantly improve chatter. ConclusionsIncreasing aspiration above 50 mL/min did not improve phacoemulsification efficiency. Increasing vacuum settings to 700 mm Hg decreases efficiency. Chatter did not significantly change with increasing aspiration and vacuum settings.

Optimization and comparison of a 0.7 mm tip with the 0.9 mm tip on an active-fluidics phacoemulsification platform

To assess the effect of varying levels of torsional power on phacoemulsification efficiency using an active-fluidics phacoemulsification platform with a 0.7mm Sonata tip. John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA. Experimental study. A 0.7mm tip was used to emulsify 2.0mm porcine lenses that had been hardened in formalin. The torsional power was varied from 10% to 100% at intervals of 10%, and efficiency and chatter were recorded. A comparison of the 0.7mm tip with the 0.9mm Balanced tip was also performed. Using a torsional power setting of 90% and 100%, the 0.7mm tip and the 0.9mm tip efficiency times were recorded. The study showed an increase in efficiency as torsional power increased. The relationship was linear and more efficient up to 90% (R2=.8025, P=.0005). Chatter was only observed at a torsional power setting of 60%. In addition, a head-to-head comparison of the 0.7mm tip with the 0.9mm tip showed that both tips were statistically similar in efficiency times, despite the smaller diameter of the 0.7mm tip. The optimum torsional power setting with the Centurion platform in conjunction with the 0.7mm tip was 90%. The efficiency of the 0.7mm tip and the 0.9mm tip was statistically similar.

Effect of high-vacuum setting on phacoemulsification efficiency

To evaluate the effect of a high-vacuum setting versus a low-vacuum setting on the efficiency of phacoemulsification. Sunderland Eye Infirmary, Sunderland, United Kingdom. Prospective clinical trial. Consecutive patients having cataract surgery in 2014were recruited. Cataract surgery was performed by 2 experiencedsurgeons using a phacoemulsification machine with monitored forced infusion. The cataractous lens was split into 2 heminuclei using the stop-and-chop technique; in 1 heminucleus, phacoemulsification and aspiration used a high-vacuum setting (600mm Hg; treatment group) and in the other heminucleus, a low-vacuum setting (350mm Hg; control group). The high and low settings were alternated by case per the operating list to reduce surgeon bias. The main outcome measures were cumulative dissipated energy (CDE) and active heminucleus removal time. One hundred sixty patients (160 eyes) were enrolled in the study, and 158 were included in the analysis. The CDE per heminucleuswas significantly lower with the high-vacuum setting than with the low-vacuum setting (mean 2.81 percent-seconds; 95% confidence interval (CI), 2.44-3.21 versus 3.81 percent-seconds; 95% CI, 3.38-4.20; P<.001). The active heminucleus removal time was significantly shorter in the high-vacuum group than the low-vacuum group (mean 27.77seconds; 95% CI, 25.26-30.19 versus 33.59seconds; 95% CI, 31.07-35.92; P<.001). The observed differences were independent of the surgeon, patient age and sex, incision size, and nucleus density. No intraoperative complications were observed in either group. A high-vacuum setting improved phacoemulsification efficiency using an active fluidics system and torsional phacoemulsification.

The impact of tip bevel angulation on phacoemulsification efficiency and chatter

The impact of tip bevel angulation on phacoemulsification efficiency and chatter

Comparison of Vacuum and Aspiration on Phacoemulsification Efficiency and Chatter Using a Monitored Forced Infusion System

To evaluate the effect of vacuum and aspiration rates on phacoemulsification efficiency and chatter using a monitored forced infusion system. Invitro animal study. John A. Moran Eye Center, University of Utah, Salt Lake City, Utah. Formalin-soaked porcine lenses were divided into 2mm cubes (tip diameter, 0.9mm). Vacuum levels were tested at 200, 300, 400, and 500mm Hg; aspiration rates at 20, 35, and 50mL/min. Torsional power was set at 60% and intraocular pressure at 50mm Hg. Increasing vacuum increased efficiency regardless of aspiration rates (R(2)= 0.92; P= .0004). Increasing aspiration further increased efficiency when vacuum was at 400 and 500mm Hg (P= .004 for 20 vs 35mL/min, P= .0008 for 35 vs 50mL/min). At 200 and 300mm Hg, efficiency only improved when increasing aspiration to 35mL/min (P < .0001 with 20 vs 35+ 50mL/min). Chatter improved with increasing vacuum, up to 400mm Hg (P= .003 for 200 vs 300mm Hg and P= .045 for 300 vs 500mm Hg). A similar trend of improved chatter was seen with increasing levels of aspiration. Vacuum improved efficiency up to 500mm Hg independent of flow. Flow has an additive effect on efficiency through 50mL/min, when vacuum is at 400mm Hg or higher, and only up to 35mL/min at vacuums less than 400mm Hg. Chatter correlated with both vacuum and flow such that increasing either parameter decreases chatter, up to 400mm Hg with vacuum.

Intraocular pressure study using monitored forced-infusion system phacoemulsification technology

To optimize phacoemulsification efficiency by varying the intraocular pressure (IOP) usingthe Centurion Vision System, a monitored forced-infusion system. John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA. Laboratory investigation. Porcine lenses were soaked in formalin and divided into 2.0mm cubes; 0.9mm balanced tips were used. Intraocular pressure levels were tested from 30 to 110mm Hg at 10mm Hg intervals. Vacuum was set at 500mm Hg, aspiration at 35mL/min, and torsional power at 60%. Efficiency (time to lens removal) and chatter (number of lens fragment repulsions from the tip) were measured. There was a linear relationship between efficiency and IOP. Increasing IOP led to an increase in efficiency (ie, to a decrease in time necessary to remove the lens fragment) (R(2)=.5769, P=.0176). Chatter correlated with IOP in the range of 30 to 50mm Hg (R(2)=.4506, P=.0448) and was minimal at higher IOPs. Increasing IOP in the monitored forced-infusion system improved efficiency. Chatter was also decreased or eliminated with increasing IOP. Additional studies will be required to understand the reasons for these findings. None of the authors has a financial or proprietary interest in any material or method mentioned.

Torsional power study using CENTURION phacoemulsification technology.

To evaluate the effect of varying levels of power on phacoemulsification efficiency using the CENTURION Vision System. Formalin-soaked porcine lenses were divided into 2-mm cubes; 0.9-mm, balanced tips were used. Torsional power levels were tested from 10% to 100% at 10% intervals. Vacuum was set to 550 mmHg, aspiration to 50 ml/min, and intraocular pressure at 50 mmHg. Efficiency (time to lens removal) and chatter (number of lens fragment repulsions from the tip) were determined. Increasing torsional power up to 60% increased efficiency. This effect was linear from 30 to 60% power (R2 = .90; P < 0.05). There were no significant differences in efficiency past 60%. Chatter was highest at 10% power and decreased linearly (R2 = .87; P = 0.007) as power was increased up to 60% power, and chatter did not improve above this power level. Power improved efficiency only up to a 60% power level, and then was negligible. Chatter correlated well with power up to the 60% level, so that as power was increased, chatter decreased. Because there are no additional benefits in efficiency past 60% power, and because chatter is minimal at 60% power, we recommend torsional ultrasound at 60% as the optimal power setting for using the CENTURION System for phacoemulsification.l.

A Comparison of Porcine Lens Storage Methods for Optimal Phacoemulsification

Abstract Objective: The study purpose was to compare effects of two porcine lens storage methods on phacoemulsification efficiency and chatter. Methods: This in vitro laboratory study was conducted at the John A. Moran Eye Center Laboratories, University of Utah. Porcine nuclei were fixed in 10% formaldehyde and cut into 2.0 mm cubes. An equal number of lens cubes either were stored in a 100% humidity chamber or were partially immersed in balanced salt solution (BSS). Using identical parameters on the phacoemulsification machine, 40 lenses that underwent each storage method were phacoemulsified every two hours for a total of ten hours. Results: Lenses stored in the 100% humidity chamber experienced a 2.25% increase in efficiency per hour (r2=0.1922; p=0.3846), while lenses stored partially immersed in BSS experienced a 1.30% increase in efficiency per hour (r2=0.4084; p=0.1719). Although we found no statistically significant difference between the two groups, the partially immersed lenses were consistently softer than the lenses that were kept in the 100% humidity chamber. Chatter was minimal throughout the testing, but showed an increase over time. Conclusion: Either the 100% humidity chamber or the partially submerged method can be used for lens storage. Despite some differences between the two storage methodologies, the differences were not statistically significant. We conclude that using either method results in a natural softening of the lenses over time which must be taken into consideration during future experiments. This necessitates the testing time to be as short as possible.