Torsional ultrasound mode versus combined torsional and conventional ultrasound mode phacoemulsification for eyes with hard cataract

Active-fluidics versus gravity-fluidics in lens extraction: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

To investigate differences in outcomes between active-fluidics and gravity-fluidics phacoemulsification systems.

METHODS

We searched PubMed, Embase, and Cochrane Library databases for randomized controlled trials (RCTs) published no later than December 1, 2021. The Cochrane Collaboration risk of bias tool was used for quality assessment. We presented the outcomes as standardized mean differences (SMDs) with 95% confidence intervals (CI). Sensitivity analysis was performed by removing studies that included ≥2 types of phacoemulsification tips.

RESULTS

We analyzed six RCTs that totally enrolled 884 patients. Patients undergoing lens extraction with active-fluidics systems exhibited lower cumulative dissipated energy (CDE), total aspiration time (TAT), and estimated fluid usage (EFU) compared with patients who did not (SMD [95% CI]: CDE, - 0.818 [ - 1.054 to - 0.582]; TAT, - 0.664 [ - 0.850 to - 0.479]; EFU, - 0.655 [ - 0.932 to - 0.378]). A sensitivity analysis revealed similar results for CDE, TAT, and EFU. For endothelial cell density (ECD) 1 week after surgery, ECD 1 month after surgery, and central corneal thickness (CCT) 1 week after surgery, outcomes of both systems were comparable (ECD at 1 week, 0.074 [ - 0.177 to 0.325]; ECD at 1 month, 0.069 [ - 0.167 to 0.305]; CCT 1 week after surgery, 0.077 [ - 0.173 to 0.328]). No severe adverse events in patients treated with either system were reported in the studies.

CONCLUSION

Active-fluidics systems are superior to gravity-fluidics systems with respect to CDE, TAT, and EFU; no differences in postoperative ECD and CCT were observed. Future studies are required to determine the reasons for heterogeneity and to detect rare adverse events.

A longitudinal-torsional mode ultrasonic needle for deep penetration into bone

This work presents a longitudinal-torsional (L-T) composite mode ultrasonic needle device for deep bone penetration. The L-T needle is a geometrically modified version of an L-mode needle whose efficacy as a prototype ultrasonic bone biopsy device has been previously demonstrated by the authors. Finite element analysis (FEA) aided in the design of the L-T needle, with the aim of maximising the achievable torsional displacement while matching the longitudinal displacement achieved by the L-mode needle. Experimental modal analysis (EMA) of the fabricated ultrasonic device was used to identify the modal parameters and validate the FEA model. Harmonic analysis then provided an insight into how the inherent nonlinearities of the high-power transducer are affected by incorporating the geometrical features that degenerate the L mode into an L-T mode. High power characterisation shows that the longitudinal displacement amplitude of the L-T mode needle is larger than that of the L-mode needle. Comparative penetration tests in fresh Wistar rat skull were evaluated by investigating cell death and cell survival. The region of statistically significant cell death was small for both devices, with the combined axial and shear motion of the L-T device causing increased osteocyte necrosis within this region. Nevertheless, the results suggest a promising environment for post-operative healing. It is shown how this technology offers a potential technique for a surgical approach to the petrous apex, an application that requires a deep penetration into bone.

Ophthalmic Viscosurgical Devices (OVDs) in Challenging Cases: a Review

Ophthalmic viscoelastic devices (OVDs) are currently used in cataract surgery and have significantly improved the safety and effectiveness of this surgical procedure. OVDs are classified according to the zero-shear viscosity and the cohesion-dispersion index in cohesive, dispersive, and viscoadaptives. OVDs create and maintain anterior chamber depth and visibility, protecting the corneal endothelium and other intraocular tissues during surgery. The selection of the most adequate OVD is especially relevant when performing cataract surgery in challenging cases, such as in hard, mature cataracts, flat anterior chamber, pseudoexfoliation syndrome, intraoperative floppy iris syndrome, or glaucoma surgery. In such cases, OVD is crucial for facilitating the surgical procedure and the associated minimal complication rate. The use of a combination of OVDs (soft-shell technique and modifications), the use of blue-colored OVDs, and the combination of sodium hyaluronate with lidocaine have also been described as useful tools in some of these challenging cases.

Supervised walking exercise therapy improves gait biomechanics in patients with peripheral artery disease

OBJECTIVE

In patients with peripheral artery disease (PAD), supervised exercise therapy is a first line of treatment because it increases maximum walking distances comparable with surgical revascularization therapy. Little is known regarding gait biomechanics after supervised exercise therapy. This study characterized the effects of supervised exercise therapy on gait biomechanics and walking distances in claudicating patients with PAD.

METHODS

Forty-seven claudicating patients with PAD underwent gait analysis before and immediately after 6 months of supervised exercise therapy. Exercise sessions consisted of a 5-minute warmup of mild walking and stretching of upper and lower leg muscles, 50 minutes of intermittent treadmill walking, and 5 minutes of cooldown (similar to warmup) three times per week. Measurements included self-perceived ambulatory limitations measured by questionnaire, the ankle-brachial index (ABI), walking distance measures, maximal plantar flexor strength measured by isometric dynamometry, and overground gait biomechanics trials performed before and after the onset of claudication pain. Paired t-tests were used to test for differences in quality of life, walking distances, ABI, and maximal strength. A two-factor repeated measures analysis of variance determined differences for intervention and condition for gait biomechanics dependent variables.

RESULTS

After supervised exercise therapy, quality of life, walking distances, and maximal plantar flexor strength improved, although the ABI did not significantly change. Several gait biomechanics parameters improved after the intervention, including torque and power generation at the ankle and hip. Similar to previous studies, the onset of claudication pain led to a worsening gait or a gait that was less like healthy individuals with a pain-free gait.

CONCLUSIONS

Six months of supervised exercise therapy produced increases in walking distances and quality of life that are consistent with concurrent improvements in muscle strength and gait biomechanics. These improvements occurred even though the ABI did not improve. Future work should examine the benefits of supervised exercise therapy used in combination with other available treatments for PAD.

Torsional and burst mode phacoemulsification for patients with hard nuclear cataract: A randomized control study

This article aims to evaluate the outcomes of torsional and burst mode phacoemulsification in hard nuclear cataracts.Eighty eyes with grade IV or V nuclear opalescence were treated with phacoemulsification and intraocular lens implantation using conventional mode (Group A, n = 40) or torsional and burst mode phacoemulsification (Group B, n = 40). For good visualization of anterior capsule, trypan blue was injected to the anterior chamber before continuous circular capsulorhexis. The mean cumulative dissipated energy and ultrasound time were recorded. The best-corrected visual acuity, endothelial cell density, and central corneal thickness were measured before and at 1 month after surgery.The cumulative dissipated energy and ultrasound time of Group B were significantly less than that of Group A. The postoperative best-corrected visual acuities of the 2 groups were comparable. At 1 month after surgery, the changes in the endothelial cell density were significantly greater in Group A than in Group B, and the changes in the central corneal thickness were not significantly different between the 2 groups.Torsional and burst mode is a safe and effective surgical method for treating hard cataracts.

Combined 30-degree bevel up and down technique against 0-degree phaco tip for phacoemulsification surgery of hard cataracts

Purpose

To evaluate the effective phaco time (EPT), cumulative dissipated energy (CDE) and nucleus emulsification time (NET) as phaco parameters with 0- and 30-degree phaco tip.

Patients and methods

This prospective, interventional and observational case series included 294 patients scheduled for cataract removal by phacoemulsification technique. Patients with nuclear cataracts of grade 4 and 5 nuclear opalescence of Lens Opacities Classification System III were included in the study. Patients were consecutively allocated to phaco chop technique with 0-degree (0-degree group, n=147) and combined bevel up and down position using 30-degree phaco tip (combined bevel up/down group, n=147). The 0-degree group had phacoemulsification with 0-degree phaco tip, while the 30-degree group had chopping of the nucleus with bevel down phaco tip and emulsification of nuclear fragments was accomplished with bevel up tip. EPT, CDE, NET and intraoperative complications were noted and compared between the groups using analysis of variance.

Results

Average EPT, CDE and NET were lower in the 30-degree group than in the 0-degree group. However, no statistically significant difference was found in EPT (P=0.0733), CDE (P=0.0663) and NET (P=0.0633) between the two groups. No serious intraoperative complications were noted. The anterior chamber was maintained throughout the procedure in both groups. No patients had wound burn and miosis during the procedure. None of the patients developed bullous keratopathy, uveitis and cystoid macular edema during the follow-up period.

Conclusion

Combined bevel up and down 30-degree tip can yield effective hard nucleus phacoemulsification. Bevel down tip of 30-degree helps in effective chopping and bevel up tip assists in emulsification of the nuclear fragments. Although combined bevel up and down 30-degree tip can yield effective hard nucleus phacoemulsification, no statistically significant difference was found in EPT, CDE and NET between the two groups.

A Rabbit Model Study to Determine the Efficacy of a Prototype Corneal Endothelium Protector during Cataract Surgery

Purpose. We evaluated the efficacy and safety of a mechanical device, the P-chute, in corneal endothelium preservation during phacoemulsification in a rabbit model. Methods. Twenty-four rabbits were randomly assigned into 2 groups. One eye of each rabbit underwent phacoemulsification that simulated the removal of a dense nucleus, with or without the P-chute. Serial slit-lamp examinations, anterior segment optical coherence tomography (ASOCT) scans, and specular microscopy were performed. Three rabbits from each group were sacrificed on postoperative days (PODs) 1, 5, 7, and 14. Histological analysis of the corneas was performed. Results. There was a trend towards lesser endothelial cell loss for the P-chute group at POD1 (4.9% versus 12.5%, p = 0.53), POD5 (10.4% versus 12.2%, p = 0.77), and POD7 (10.5% versus 17.2%, p = 0.52). There was no significant difference in the corneal thickness (p = >0.05) between the 2 groups. The insertion of the device was challenging. The use of the P-chute only added an extra 15% to the surgical time. Conclusions. There was a trend towards better endothelium preservation with the P-chute even though the results were not statistically significant. We believe that the device could be useful in certain surgical situations. Further work is needed to improve the device insertion.

Torsional power study using CENTURION phacoemulsification technology

BACKGROUND

To evaluate the effect of varying levels of power on phacoemulsification efficiency using the CENTURION Vision System.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Customized Clinical Practice Guidelines for Management of Adult Cataract in Iran

Purpose:

To customize clinical practice guidelines (CPGs) for cataract management in the Iranian population.

Methods:

First, four CPGs (American Academy of Ophthalmology 2006 and 2011, Royal College of Ophthalmologists 2010, and Canadian Ophthalmological Society 2008) were selected from a number of available CPGs in the literature for cataract management. All recommendations of these guidelines, together with their references, were studied. Each recommendation was summarized in 4 tables. The first table showed the recommendation itself in clinical question components format along with its level of evidence. The second table contained structured abstracts of supporting articles related to the clinical question with their levels of evidence. The third table included the customized recommendation of the internal group respecting its clinical advantage, cost, and complications. In the fourth table, the internal group their recommendations from 1 to 9 based on the customizing capability of the recommendation (applicability, acceptability, external validity). Finally, customized recommendations were sent one month prior to a consensus session to faculty members of all universities across the country asking for their comments on recommendations.

Results:

The agreed recommendations were accepted as conclusive while those with no agreement were discussed at the consensus session. Finally, all customized recommendations were codified as 80 recommendations along with their sources and levels of evidence for the Iranian population.

Conclusion:

Customization of CPGs for management of adult cataract for the Iranian population seems to be useful for standardization of referral, diagnosis and treatment of patients.

Effect of torsional mode phacoemulsification on cornea in eyes with/without pseudoexfoliation

AIM

To evaluate the effect of torsional mode phacoemulsification on central corneal thickness, corneal endothelial cell density, and morphology in eyes with/without pseudoexfoliation (PEX) syndrome.

METHODS

Fourty-two consecutive patients with and 42 patients without PEX as a control group scheduled for cataract surgery was studied. Phacoemulsification, using OZiL IP system, was performed with quick chop technique. Using noncontact specular microscopy, the central endothelial cell density (ECD), coefficient of variation, percentage of hexagonal cells, and the central corneal thickness (CCT) were evaluated preoperatively and postoperatively at 1, 7 and 30d.

RESULTS

The ECD in PEX syndrome was statistically significantly lower than that in the control group preoperatively and postoperatively (P≤0.001). Percentage change in ECD was statistically significantly higher in PEX than that in control group after surgery follow up (P≤0.04). There was no statistically significant difference between both groups comparing percentage of hexagonal cells and coefficient of variation in the cell size before and after the surgery. At 1 and 7d after surgery, percentage change in CCT was statistically significantly higher in PEX group than that in the control group (P≤0.041).

CONCLUSION

Although torsional mode phacoemulsification and intraocular lens (IOL) implantation provided a safe and favorable surgical outcome in patients with/without PEX, torsional phacoemulsification led to significantly higher ECD loss in the PEX group than that in the control group during the whole follow up period. In addition, more corneal swelling in the PEX group than that in the control group during the early postoperative period has indicated that the corneal endothelium, in presence of PEX endotheliopathy, seems to be more susceptible to the effects of phacoemulsification surgery in eyes with PEX. The increased risk of anterior chamber manipulations in patients with PEX should be taken into account for an increased risk of bullous keratopathy.

Evaluation of early results of quick-chop phacoemulsification in the patients with high myopic cataract

AIM

To assess the early surgical outcomes of quick-chop phacoemulsification technique in patients with high myopia.

METHODS

The data of patients with high myopia who underwent quick-chop phacoemulsification were reviewed retrospectively. There were 42 eyes of 31 patients. The axial length was more than 26 mm in all eyes. All eyes underwent quick-chop phacoemulsification surgery with the placement of an intraocular lens (IOL) in the capsular bag. Postoperative visits were performed at 1, 3d; 2wk, 1mo. Early postoperative best corrected visual acuity (BCVA), preoperative and postoperative corneal endothelial cell density (ECD), central corneal thickness (CCT) and postoperative complications were assessed. Paired sample t-test or Wilcoxon tests were used to compare data between preoperative and postoperative data.

RESULTS

There was no statistically significant difference between preoperative and postoperative ECD and CCT. Retinal detachment was developed in one eye at postoperative first day. There was an iris prolapsus from side port insicion.

CONCLUSION

Quick-chop phacoemulsification technique is a safe surgical technique. However we can encounter some complications in high myopic eyes due to histopathological differences. Both side port and clear corneal tunnel insicion size is crucial for preventing postoperative complications. If any persistent leakage is noticed, suture should be placed.

Phacoemulsification induced transient swelling of corneal Descemet's Endothelium Complex imaged with ultra-high resolution optical coherence tomography

Purpose

Thickness changes of corneal sub-layers after phacoemulsification were investigated by spectral domain ultra-high resolution optical coherence tomography (UHR-OCT).

Methods

The corneas (n = 26) of 26 age-related cataract surgery patients were studied. UHR-OCT was used to evaluate the thickness of Descemet’s Endothelium Complex (DEC), stroma, Bowman’s layer, epithelium, and full cornea at the center (CCT) before, one day after, and one week after surgery. Non-contact specular microscopy measured CCT, endothelial cell density, and morphology.

Results

The DEC, stroma, Bowman’s layer, and epithelium were visualized by UHR-OCT. Before surgery, the DEC in all cases appeared as a translucent space between two smooth opaque lines. One day after surgery, the posterior corneal surfaces in half of the eyes were wavy and irregular. Compared to the baseline, one day after surgery the thickness increases of the DEC, stroma, and CCT were 4.3 ± 2.6 µm, 25.5 ± 24.9 µm, and 32.1 ± 26.6 µm, respectively (P < 0.001). The morphology of the DEC and the CCT recovered to baseline one week after surgery (P > 0.05), but endothelial cell density was 8.7% less than at baseline. There were no significant changes in Bowman’s layer and epithelium after the operation. The pre-operative DEC thickness was positively correlated with the decreased endothelial cell density at 1 day after surgery (r = 0.55, P = 0.003).

Conclusions

The DEC showed edematous thickening and different degrees of morphological changes after phacoemulsification. The DEC deformation and corneal edema recovered by one week after surgery, which indicated recovery of endothelial function. UHR-OCT is a useful tool to evaluate function of the DEC after phacoemulsification. Pre-operative DEC thickness may indicate the integrity of the endothelium and could be used for predicting endothelial cell loss after phacoemulsification.

Small-gauge transconjunctival vitrectomy with phacoemulsification in the pupillary plane of dense retained lens matter on perfluorocarbon liquids after complicated cataract surgery

BACKGROUND

To evaluate the visual outcomes, efficacy, and complications of 23-gauge pars plana vitrectomy followed by phacoemulsification using torsional ultrasound of dense retained lens matter on perfluorocarbon liquids (PFCLs) after complicated cataract surgery.

METHODS

The case notes of 34 consecutive patients operated upon with retained lens matter after complicated cataract surgery by one surgeon were reviewed. Twenty-one of the 32 cases were able to be managed using the vitrectomy cutter alone, but 13 cases with dense lens matter were managed using 23-G vitrectomy followed by torsional ultrasound of the retained lens via the original corneal incision after floating it up to the pupillary plane on PFCLs. Case notes of these 13 patients were reviewed to ascertain clinical features, results, and any complications.

RESULTS

The mean age of the 13 patients was 79 years. The procedure was completed in all cases without using an intravitreal fragmatome. All cases were aphakic prior to vitrectomy surgery. Ten patients had a sulcus fixated IOL inserted at the time of vitrectomy and three had an angle-supported anterior chamber IOL inserted. Mean post-operative visual acuity at 3 months was 0.24 (median 6/9). Eleven of the 13 patients (85 %) had a best postoperative corrected visual acuity of ≥6/12. One patient developed cystoid macular oedema that was successfully treated. There were no cases of retinal detachment.

CONCLUSION

The outcome of 13 patients operated on with transconjunctival vitrectomy with phacoemulsification of dense retained lens matter on top of PFCLs is described. The technique was used successfully, with good visual acuity outcomes and a low complication rate.

Comparative analysis of corneal morphological changes after transversal and torsional phacoemulsification through 2.2 mm corneal incision

Purpose

This paper compares and evaluates the corneal morphological changes occurring after cataract surgery through a 2.2 mm corneal incision. We use two platforms for comparison and evaluation, transversal and torsional phacoemulsification.

Patients and methods

This study includes 139 consecutive cataractous eyes (nuclear color 2–4, according to the Lens Opacities Classification System III [LOCSIII]) of 82 patients undergoing cataract surgery through a 2.2 mm corneal incision. Two different phacoemulsification platforms were used and assigned randomly: we used the WhiteStar Signature^® system with the Ellips™ FX transversal continuous ultrasound (US) mode for group I (mean age: 65.33 ± 6.97 years), and we used the Infiniti^® system with the OZil^® Intelligent Phaco (IP) torsional US mode for group II (mean age: 64.02 ± 7.55 years). The corneal endothelium and pachymetry were evaluated preoperatively and at 1 month postoperatively. Incision size changes were also evaluated.

Results

All surgeries were uneventful. Before intraocular lens implantation, the mean incision size was 2.24 ± 0.06 mm in both groups (P = 0.75). In terms of corneal endothelial cell density, neither preoperative (I vs II: 2304.1 ± 122.5 cell/mm² vs 2315.6 ± 83.1 cell/mm², P = 0.80) nor postoperative (I vs II: 2264.1 ± 124.3 cell/mm² vs 2270.3 ± 89.9 cell/mm², P = 0.98) differences between the groups were statistically significant. The mean endothelial cell density loss was 1.7% ± 1.6% and 2.0% ± 1.4% in groups I and II, respectively. Furthermore, no significant differences between groups I and II were found preoperatively (P = 0.40) and postoperatively (P = 0.68) in central pachymetry. With surgery, the mean increase in central pachymetry was 28.1 ± 23.6 μm and 24.0 ± 24.0 μm in groups I and II, respectively (P = 0.1).

Conclusion

Ellips™ FX transversal and OZil^® IP torsional phacoemulsification modes are safe for performing cataract surgery, inducing minimal corneal thickness and endothelial changes.

The changing fate of the corneal endothelium in cataract surgery

PURPOSE OF REVIEW

Corneal endothelial cell loss remains a well known, undesirable side-effect of cataract surgery that may, in severe cases, negatively impact patients' postoperative visual outcomes. This article reviews the current literature and describes in detail how the degree of corneal endothelial cell loss is influenced by specific patient risk factors, as well as the arrival of newer surgical techniques and technologies.

RECENT FINDINGS

Recent studies have demonstrated a reduction in corneal endothelial cell loss after phacoemulsification with the use of viscoelastic materials and modifications in phacoemulsification technology. Some patient characteristics may predispose patients to increased endothelial cell loss during cataract surgery.

SUMMARY

Advances in surgical technique, the implementation of newer surgical technologies such as torsional ultrasound and viscoelastic devices, and aspects of patients' preexisting medical history may lead to varying degrees of endothelial cell loss after cataract surgery. Appropriately addressing these issues during the perioperative period may improve the rate of endothelial cell loss, and thus further enhance the visual outcome of patients undergoing cataract surgery.