Endothelial cell integrity after phacoemulsification with 2 different handpieces

Surgical Efficiency Comparison Between Two Phacoemulsification Systems

Purpose

To assess the surgical efficiency in cataract surgery comparing two phacoemulsification systems.

Methods

Prospective, consecutive-comparative study in a two-site private practice. Three hundred and one eyes undergoing standard or femtosecond laser-assisted (FLACS) cataract surgery with either the R-Evo Smart (BVI, Waltham, USA) and/or the Centurion Vision System (Alcon, Fort Worth, USA). Preoperative eye characteristics (degree of cataract using the lens opacities classification system LOCS III grading) and intraoperative outcomes (total ultrasound time and total estimated fluid aspirated/drainage bag weighting) were registered in all cases.

Results

One hundred and fifty-five eyes undergone cataract surgery with the R-Evo Smart and 146 eyes with the Centurion Vision System phacoemulsification systems. Mean cataract grade was 3.07 ± 0.78 and 2.96 ± 0.85 for the R-Evo Smart and Centurion Vision System groups, respectively (p = 0.12). Mean total ultrasound time was 18.99 ± 12.85 and 40.24 ± 21.91 seconds for the R-Evo Smart and Centurion Vision System groups, respectively (p < 0.01). Mean total estimated fluid aspirated/drainage bag weighting was 53.00 ± 14.56 g and 54.33 ± 14.88 cc for the R-Evo Smart and Centurion Vision System groups, respectively (p = 0.21). Considering non-FLACS surgery (98 eyes with the R-Evo Smart and 63 eyes with the Centurion Vision System), mean cataract grade was 2.95 ± 0.74 and 2.97 ± 0.91 for the R-Evo Smart and Centurion Vision System groups, respectively (p = 0.44). Mean total ultrasound time was 19.96 ± 11.20 and 42.84 ± 28.35 seconds for the R-Evo Smart and Centurion Vision System groups, respectively (p < 0.01). Mean total estimated fluid aspirated/drainage bag weighting was 55.95 ± 14.76 g and 55.97 ± 13.62 cc for the R-Evo Smart and Centurion Vision System groups, respectively (p = 0.49). No adverse events were found in the two groups of eyes.

Conclusion

The objective measurement of surgical efficiency through total ultrasound time during lens removal and fluid consumption during both lens removal and irrigation/aspiration proved R-Evo Smart to be an efficient phacoemulsification platform, in comparison with the current standard of care Centurion Vision System.

Mechanical protective effect of lens anterior capsule disc on corneal endothelial cells during femtosecond laser-assisted cataract surgery in a rabbit model

PURPOSE

To evaluate the effects of a novel technique using an isolated lens anterior capsule disc (LACD) to protect corneal endothelial cells in rabbit eyes during femtosecond laser-assisted cataract surgery.

METHODS

Experimental study. 40 rabbits were divided into endothelium-protected (experimental) and control groups, with 20 rabbits in each group. In the experimental group, after femtosecond laser capsulotomy, the isolated capsule disc was lifted to the corneal endothelium by an ophthalmic viscosurgical device. The endothelium was damaged for 1 min with an ultrasonic probe. The control group underwent the same surgery, except that the disc was removed immediately after capsulorhexis. Corneal endothelioscopy was performed preoperatively and on postoperative days (PODs) 3 and 7 to observe endothelial cell counts (ECC) and endothelial cell loss rate. Central corneal thickness (CCT) was measured before and at PODs 1, 3 and 7.

RESULTS

There were 3.59%±1.88% (p < 0.001) and 2.92%±2.14% (p < 0.001) loss of ECC in experimental group at POD3 and POD7, respectively, while those in the control group were 11.62%±7.43% and 10.34%±5.77%, respectively. On POD 1, the difference in central corneal thickness was significant(P = 0.019) between the two groups. At POD 3 and POD 7, CCT was not significantly different (P = 0.597;0.913) between the two groups.

CONCLUSIONS

The isolated LACD technique significantly reduced damage to the endothelium caused by ultrasonic energy and protects corneal endothelial cells during phacoemulsification.

Comparison of effective phacoemulsification time and corneal endothelial cell loss using three different ultrasound frequencies: A randomized controlled trial

Purpose

Comparison of three ultrasound (US) frequencies for phacoemulsification of hard cataracts to determine a frequency that makes phacoemulsification more efficacious and safer.

Methods

A randomized controlled trial was undertaken at a medical college and hospital. In total, 207 patients with grade 5.6-6.9 (LOCS III) senile cataract were randomized into three groups. Group I underwent phacoemulsification with 28-kHz frequency, group II with 42-kHz frequency, and group III with 53-kHz frequency. The effective phacoemulsification time (EPT) and estimated fluid usage (EFU) were compared intraoperatively. The endothelial cell parameters were analyzed for 6 months.

Results

The groups were matched for age (P = 0.467), gender (P = 0.497), nuclear grade (P = 0.321), and anterior chamber depth (P = 0.635). The EPT and EFU were significantly lower in group III, compared to group II and group I, with P < 0.0001 and P < 0.0001, respectively. Postoperatively, the endothelial cell density (ECD) was significantly higher in group III at 1 month (P < 0.0001), 3 months (P < 0.0001), and 6 months (P < 0.0001). The percentages of ECD loss were also significantly lower in group III; the difference was statistically significant (P < 0.0001) up to 6 months postoperatively.

Conclusion

Higher frequency ultrasound was associated with a lower EPT and EFU as well as better endothelial preservation than lower frequencies in hard cataracts.

Randomized Controlled Trial Comparing Femtosecond Laser-Assisted with Conventional Phacoemulsification on Dense Cataracts

PURPOSE

To compare the benefit of femtosecond laser-assisted cataract surgery (FLACS) versus phacoemulsification (PE) and 2 fragmentation patterns in managing dense cataracts.

DESIGN

Randomized controlled trial.

METHODS

Patients with nuclear opacity (NO) grade >5 (Lens Opacities Classification System III) were enrolled at the Singapore National Eye Centre. Patients who were unsuitable for FLACS, whose corneal endothelial cell count (ECC) was <1,500 cells/mm², or had cataracts with additional complexities were excluded from the study. Eyes were randomized to PE, 600 μm grid (FLACSg), or 16-segment fragmentation (FLACS16) in 2:1:1 ratio. The Victus (Bausch & Lomb) laser platform and in situ phacoemulsification chop technique was used. Data for patient demographics, preoperative, and 1 month postoperative best-corrected visual acuity (BCVA), ECC, effective phacoemulsification time (EPT), and perioperative complications were collected. Outcome measurements were the loss of ECC at 1 month and EPT.

RESULTS

Ninety-three patients were randomized to PE (48), FLACSg (22), and FLACS16 (23). Majority were Chinese (87; 93.5%). Mean age was 74.3 ± 8.8 years of age. Cataracts were mostly graded as NO 5-6 (49; 61.3%). EPT among treatment arms was not different (P = .097, one-way ANOVA) but was significantly higher for NO >6 than NO <6 (P < .001, general linear model). ECC loss was significantly less in FLACSg than in PE (P = .018, Bonferroni correction). Mean 1-month postoperative LogMAR BCVA (0.23 ± 0.20) was significantly better than preoperative BCVA (1.02 ± 0.85; P < .001, paired t test) but not different between PE and FLACS.

CONCLUSIONS

FLACSg but not FLACS16 significantly lowered the mean ECC loss during phacoemulsification in dense cataracts.

Comparison of effective phacoemulsification time and corneal endothelial cell loss using 2 ultrasound frequencies

PURPOSE

To compare 2 ultrasound (US) frequencies for phacoemulsification for moderate to hard cataract to determine a frequency that makes phacoemulsification safer and more efficacious.

SETTING

Post Graduate Institute of Medical Education and Research, New Delhi, India.

DESIGN

Randomized controlled trial.

METHODS

Patients with grade 4.0 to 6.9 senile cataract were randomized to 2 groups. Group A had lower frequency (28 kHz) phacoemulsification, and Group B had higher frequency (42 kHz) phacoemulsification. The effective phacoemulsification time (EPT) and estimated fluid usage (EFU) were compared intraoperatively. The endothelial parameters were assessed over 1 year.

RESULTS

Both groups comprised 80 patients. The groups were matched for age (P = .533), sex (P = .263), and nuclear grade (nuclear color, P = .496; nuclear opalescence, P = .622). Group B had significant reductions in EPT (P = .008) and EFU (P = .004) compared with Group A. Postoperatively, the endothelial cell density (ECD) was significantly higher in Group B at 1 month (P = .004), 3 months (P = .003), 6 months (P = .004), 9 months (P = .002), and 1 year (P = .003). The percentages of ECD loss were also significantly lower in Group B; the difference was statistically significant up to 1 year postoperatively even after adjustments for age, grade of cataract, EPT, and EFU.

CONCLUSION

Higher frequency phacoemulsification was associated with a lower EPT and EFU as well as better endothelial preservation than a lower frequency.

New ex vivo model of corneal endothelial phacoemulsification injury and rescue therapy with mesenchymal stromal cell secretome

PURPOSE

To develop a reproducible ex vivo model of corneal endothelial cell injury using phacoemulsification in porcine eyes and to evaluate the effects of mesenchymal stromal cell secretome in this injury model.

SETTING

Department of Ophthalmology, University of Illinois at Chicago, Illinois, USA.

DESIGN

Experimental study.

METHODS

A corneal endothelial injury model was optimized using different powers and durations of ultrasound energy inside ex vivo porcine eyes. Conditioned media from corneal mesenchymal stem cells was collected under serum-free conditions from passages 4 to 6. Immediately after the phacoemulsification injury, the anterior chamber fluid was replaced with unconditioned media or conditioned media and incubated at 37°C for 4 hours. At the end, endothelial cell viability was evaluated using trypan blue staining and analyzed with ImageJ software.

RESULTS

Using specific parameters (50% power for 30 seconds), phacoemulsification inside fresh porcine eyes led to a consistent level of endothelial cell injury. Incubation with corneal mesenchymal stromal cell-conditioned media after the injury significantly reduced endothelial cells loss compared with unconditioned media (mean 1.29% ± 0.91% [SD] and 5.33% ± 3.24%, respectively, P < .05).

CONCLUSIONS

Phacoemulsification inside fresh porcine eyes provided a reproducible model to study endothelial cell injury. Treatment with corneal mesenchymal stromal cell secretome after injury appeared to significantly enhance the survival of corneal endothelial cells. This might provide a new strategy for preventing corneal endothelial cell loss after phacoemulsification or other endothelial injuries. Further in vivo studies are necessary to determine the therapeutic potential.

Comparison of Divide and Conquer and Phaco-Chop Techniques during Fluid-Based Phacoemulsification

PURPOSE

To determine whether, similar to ultrasound phaco-emulsification, applied energy and surgery time decrease using phaco-chop nucleus fragmentation method compared to divide and conquer technique using the fluid-based system.

METHODS

This prospective, comparative, randomized clinical study included patients with cataract who were randomly assigned to use either standard divide and conquer technique (25 eyes of 25 patients, Group 1) or Nagahara phaco-chop maneuver (25 eyes of 25 patients, Group 2) during fluid-based phaco-emulsification. Surgical parameters were recorded and patients were examined 1 day, 10 days, and 1 month after surgery. Statistical analyses were performed using the paired test of Wilcoxon.

RESULTS

Fluid-based time, mean fluid-based magnitude, effective fluid-based time, and the number of pulses were significantly less using phaco-chop technique compared to divide and conquer method (p<0.001). Surgery time was similar using the two nucleofractis techniques (p=0.97). Visual acuities showed no statistical differences between the two groups (p>0.05).

CONCLUSIONS

Nuclear fragmentation can be performed with Nagahara phaco-chop technique using the fluid-based system as well. The applied fluid-based energy decreases compared to divide and conquer method. However, surgery time is not reduced due to the difficulties reaching the full occlusion necessary to hold the nucleus during the chop maneuver.

Biofouling of surgical power tools during routine use

Surgical power tools (SPTs) are frequently used in many surgical specialties such as dentistry, orthopaedics, ophthalmology, neurology, and podiatry. They have complex designs that may restrict access to cleaning and sterilization agents and frequently become contaminated with microbial and tissue residues following use. Due to these challenges, surgical power tools can be considered the weak link in the decontamination cycle and present a potential for iatrogenic transmission of infection. We aimed to review the existing literature on the decontamination of surgical power tools and associated iatrogenic transmission of infection. A search of the medical literature was performed using Ovid online using the following databases: Ovid Medline 1950-2014, Embase 1980-2014, and EBM Reviews Full Text--Cochrane DSR, ACP Journal Club, and Dare. Despite challenges to decontamination processes, reported episodes of iatrogenic infection directly linked to SPTs appear rare. This may reflect a true picture but more likely represents incomplete reporting, failure to investigate power tools, or lack of surveillance linking surgical site infections (SSIs) to power tools. Healthcare professionals should be aware of the complexities associated with the decontamination of different SPTs, and should review manufacturers' reprocessing instructions prior to purchase. More clarity is required in the manufacturers' validation of these reprocessing instructions. This particularly applies to the emerging surgical robot systems that present extreme challenges to decontamination between uses. Investigation of cross-infection incidents or SSI surveillance should include an element of assessment of SPT decontamination to further elucidate the contribution of SPTs to skin and soft tissue infections.

Ozil® versus conventional ultrasound phacoemulsification: a randomized comparative study

The purpose of this study is to compare and assess the performance and the postoperative outcomes of torsional mode and ultrasound (US) mode performed in the phacoemulsification of cataract with different nuclear densities. This is a randomized comparative clinical study. Two groups of 75 eyes (the first operated by Ozil(®) and the second by US) were comparable in age, gender, cataract density, corneal incision size, and intraocular lens type. We assessed peroperative parameters: US time (UST) and cumulative dissipated energy (CDE). Postoperative outcome measures were corneal edema and final best-corrected visual acuity. The UST was significantly lower in the ozil(®) group for all nucleus grades (73.43 s ± 8.3 with US vs. 46.02 s ± 23 with Ozil(®)) (p = 0.0003). The CDE was lower in the Ozil(®) group for grade III and IV cataract (p = 0.005). However, no significant difference was noted for grade II cataract (p = 0.07). Immediate postoperative corneal edema was significantly harder in the US group (p = 0.00002). The mean one month postoperative visual acuity was 0.2 ± 0.03 logMAR and 0.15 ± 0.07 logMAR, respectively, in the US group and the Ozil(®) group (p = 0.06). Ozil(®) mode seems to dissipate less energy in the eye than US mode. The visual outcome at one month is comparable in the two groups.

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.

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

PURPOSE

The objective of this study was to evaluate endothelial changes between torsional and longitudinal phacoemulsification 2 years after cataract surgery.

DESIGN

This was a prospective, randomized, controlled clinical trial.

METHODS

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).

RESULTS

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.

CONCLUSIONS

There is no difference between the ECL between torsional and longitudinal phacoemulsification up to 2 years after cataract surgery.

Comparison of microcoaxial with standard clear corneal incisions in torsional handpiece cataract surgery

AIM

To evaluate the effect of torsional handpiece incision size on phacodynamics and endothelial cell loss (ECL) in cataract surgery.

DESIGN

Prospective, observer-masked study at the Department of Ophthalmology and Visual Science, Catholic University of Korea, Seoul St. Mary's Hospital, Seoul, Korea.

PARTICIPANTS

This study was conducted on 60 eyes of 60 patients who underwent phacoemulsification.

METHODS

Cataract surgery was performed on 28 eyes using a 0.9-mm micro 45-degree Kelman ABS (aspiration bypass system) tip through a 2.8-mm standard incision, and on 32 eyes using a 0.9-mm mini-flared 45-degree Kelman ABS tip through a 2.2-mm microcoaxial incision. As main outcome measures, intraoperative phacodynamics (cumulative dissipated energy, CDE, and balanced salt solution, BSS, use), central corneal thickness (CCT) and endothelial cell count (ECC) were investigated.

RESULTS

The CDE was lower in the microcoaxial incision (2.2-mm) group than in the standard incision (2.8-mm) group (p = 0.038). The ECC loss at 6 months was significantly lower in the microcoaxial incision group than in the standard incision group (p = 0.048). There were no differences in BSS use or CCT between the two groups.

CONCLUSIONS

Torsional ultrasound phacoemulsification using microcoaxial incision with a mini-flared tip resulted in less energy use and less ECL compared with standard incision with a micro tip.

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

PURPOSE

To compare the intraoperative and postoperative outcomes of conventional longitudinal phacoemulsification and torsional phacoemulsification.

SETTING

Department of Ophthalmology, University of Leipzig, Germany.

DESIGN

Randomized single-center clinical trial.

METHODS

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.

RESULTS

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).

CONCLUSION

The torsional mode was as safe as the longitudinal mode in phacoemulsification for age-related cataract.

Hydroxyl free radical production during torsional phacoemulsification

PURPOSE

To quantitate free radical generation during phacoemulsification using an ultrasonic phacoemulsification device that includes a torsional mode and evaluate tip designs specific to the torsional mode.

SETTING

Chemistry and Biochemistry Department, Utah State University, Logan, Utah, USA.

DESIGN

Experimental study.

METHODS

Experiments were performed using the Infiniti Vision System and OZil handpiece. Hydroxyl radical concentrations in the aspirated irrigation solution during torsional phacoemulsification were quantitated as nanomolar malondialdehyde (nM MDA) and determined spectrophotometrically using the deoxyribose assay.

RESULTS

The mean free radical production during phacoemulsification with torsional modality at 100% amplitude was 30.1 nM MDA ± 5.1 (SD) using a 0.9 mm 45-degree Kelman tapered ABS tip. With other tip designs intended for use with the torsional modality, free radical production was further reduced when fitted with the 0.9 mm 45-degree Kelman mini-flared ABS tip (13.2 ± 5.6 nM MDA) or the 0.9 mm 45-degree OZil-12 mini-flared ABS tip (14.3 ± 6.7 nM MDA). Although the measurements resulting from the use of the latter 2 tips were not statistically significantly different (P ≈ .25), they were different from those of the tapered tip (P<.0001).

CONCLUSIONS

The MDA concentration in the aspirated irrigation solution using the torsional modality was approximately one half that reported for the handpiece's longitudinal modality in a previous study using the same bent-tip design (Kelman tapered, P<.0001). The level of MDA was further reduced approximately one half with torsional-specific tips.

The effects of blunt trauma and cataract surgery on corneal endothelial cell density

PURPOSE

This study was designed to investigate the effects of trauma and cataract surgery on corneal endothelial cell density (ECD) in patients with a traumatic cataract due to blunt trauma without globe laceration.

MATERIALS AND METHODS

In this prospective study, 31 subjects with traumatic cataract (traumatic cataract group) and 30 subjects with a senile cataract (control group) were enrolled. The subjects with traumatic cataract were subdivided into two groups: uncomplicated surgery subgroup (n = 19) in which subjects underwent standard phacoemulsification with intraocular lens implantation and complicated surgery subgroup (n = 12) in which subjects underwent cataract surgery other than standard phacoemulsification. The ECD of the traumatic cataract group and the control group was compared preoperatively and at 3 months or later postoperatively. A P value less than 0.05 was considered statistically significant.

RESULTS

The ECD in the eyes with traumatic cataract was 13.1% lower than that for healthy eyes preoperatively (P = 0.043). Postsurgical ECD decreased by 16.7% in complicated surgery subgroup and 11.9% in uncomplicated surgery subgroup (P = 0.049) after 3 months postoperatively. The ECD decreased by 10.8% in the control group (P = 0.489).

CONCLUSIONS

Patients with cataracts due to blunt trauma had a decreased endothelial cell count, which was significantly aggravated by cataract surgery. The loss of corneal endothelium cells due to surgery depends on the surgical approach.

Heat production: Longitudinal versus torsional phacoemulsification

PURPOSE

To compare the heat production of longitudinal versus torsional phacoemulsification under strict laboratory test conditions.

SETTING

Department of Ophthalmology, David Geffen School of Medicine at UCLA, and Jules Stein Eye Institute, Los Angeles, California, USA.

METHODS

Two Infiniti phacoemulsification handpieces were inserted into silicone test chambers filled with a balanced salt solution and imaged serially using a thermal camera. Incision compression was simulated by suspending 25.3 g weights from the silicone chambers. To simulate occlusion of the phacoemulsification tip, the aspiration line was clamped. Peak temperatures were measured 0, 10, 30, 60, and 120 seconds after the commencement of continuous ultrasound power. The 2 handpieces, operating exclusively in longitudinal or torsional modes, were compared 3 ways: (1) using the same power displayed on the instrument console, (2) using identical stroke lengths, and (3) using the same applied energy, a product of stroke length and frequency.

RESULTS

For all 3 comparisons, torsional phacoemulsification resulted in lower temperatures at each time point. At the same displayed power setting, the scenario most familiar to cataract surgeons, longitudinal phacoemulsification elevated temperatures up to 41.5 degrees C more than torsional phacoemulsification.

CONCLUSIONS

Torsional phacoemulsification generated less heat than longitudinal phacoemulsification in all 3 comparison tests. Lower operating temperatures indicate lower heat generation within the same volume of fluid, and this may provide additional thermal protection during cataract surgery.

Effect of hydrodynamic parameters on corneal endothelial cell loss after phacoemulsification

PURPOSE

To evaluate the effect of power, vacuum, and flow rate on endothelial cell loss after phacoemulsification.

SETTING

Labbafinejad Medical Center Medical Center, Tehran, Iran.

METHODS

In a prospective randomized clinical trial, phacoemulsification was performed in 2 groups (high vacuum and low vacuum) with 3+ nuclear sclerosis. The stop-and-chop technique was used with the Sovereign machine. Machine parameters during the chop stage were vacuum 400 mm Hg in the high-vacuum group and 200 mm Hg in the low-vacuum group and flow rate, 40 cc/min and 20 cc/min, respectively. Endothelial cell density preoperatively before and 1, 6, and 12 weeks postoperatively were compared.

RESULTS

Each group comprised 30 eyes. The mean US power was 9.2% +/- 4.3% (SD) in the low-vacuum group and 13.1% +/- 4.6% in the high-vacuum group (P = .001) and the mean phaco time, 1.28 +/- 1.0 minutes and 0.88 +/- 0.6 minutes, respectively (P = .04). Total US energy and total fluid consumed were similar between groups. After 12 weeks, the mean endothelial cell loss was 9.0% +/- 4.0% in the low-vacuum group and 9.6% +/- 4.6% in the high-vacuum group (P = .6). There was a relationship between total US energy and endothelial loss (P<.001); however, total fluid volume was not a significant predictor (P = .19).

CONCLUSIONS

Vacuum level did not have a significant effect on total US energy or total fluid consumed during phacoemulsification. There was a strong relationship between total US energy and endothelial cell loss but not between total infused fluid and endothelial cell loss.

Torsional mode versus conventional ultrasound mode phacoemulsification: randomized comparative clinical study

PURPOSE

To compare the intraoperative and short-term postoperative outcomes of cataract surgery performed with torsional mode and conventional ultrasound mode using the Infiniti Vision System (Alcon Laboratories).

SETTING

Cataract Service, Zhongshan Ophthalmic Center, Sun-Yat-Sen University, Guangzhou, China.

METHODS

In this randomized comparative study, 525 eyes were assigned to phacoemulsification by torsional mode or conventional ultrasound (US) mode. The surgery was performed by an experienced surgeon, and the outcomes were evaluated by an examiner who was masked to treatment assignments. Primary outcome measures were US time (UST), cumulative dissipated energy (CDE), and surgical complications. Patients were seen 1, 7, and 30 days after surgery. Postoperative outcome measures were the final best corrected visual acuity (BCVA) and the change in corneal clarity, central corneal thickness (CCT), and endothelial cell count.

RESULTS

The US group had 262 eyes and the torsional group, 263 eyes. All patients completed the follow-up visits. In the eyes with nucleus density grades of 1, 2, 3, and 4, the mean UST was 10.25 seconds +/- 7.4 (SD), 25.14 +/- 5.5 seconds, 36.45 +/- 8.3 seconds, and 61.44 +/- 17.8, respectively, in the US group and 8.32 +/- 6.8 seconds, 18.45 +/- 7.2 seconds, 29.48 +/- 12.4 seconds, and 48.39 +/- 20.3 seconds, respectively, in the torsional group (P<.001); the mean CDE was 1.25 +/- 0.5, 4.18 +/- 1.2, 8.59 +/- 6.5, and 16.51 +/- 9.6, respectively, in the US group and 0.94 +/- 0.3, 3.13 +/- 2.7, 7.47 +/- 12.6, and 14.08 +/- 8.3, respectively, in the torsional group (P<.001). At 1 day and 7 days, the mean BCVA was 0.23 +/- 0.12 logMAR and 0.00 +/- 0.10 logMAR, respectively, in the US group and 0.18 +/- 0.11 logMAR and -0.08 +/- 0.05 logMAR, respectively, in the torsional group (P<.001). At 30 days, the mean BCVA was -0.10 +/- 0.07 logMAR and -0.12 +/- 0.06 logMAR in the US group and the torsional group, respectively (P>.01). At 1 day and 7 days, the mean CCT was 625 +/- 80 microm and 568 +/- 37 microm, respectively, in the US group and 601 +/- 35 microm and 559 +/- 40 microm, respectively, in the torsional group (P<.001). At 30 days, the mean CCT was 531 +/- 30 microm in the US group and 529 +/- 39 microm in the torsional group (P>.01). At 7 days and 30 days, the mean central corneal endothelial cell count was 2135 +/- 858 cells/mm(2) and 2084 +/- 527 cells/mm(2), respectively, in the US group and 2004 +/- 656 cells/mm(2) and 1953 +/- 615 cells/mm(2), respectively, in the torsional group (P<.001).

CONCLUSION

The torsional mode may provide more effective lens removal with a lower level of phacoemulsification time and energy.

Corneal endothelial function after phacoemulsification using the fluid-based system compared to conventional ultrasound technique

AIM

To quantitatively assess corneal endothelial changes after phacoemulsification with the fluid-based system compared to conventional ultrasound technique.

METHODS

This prospective, randomized clinical study included patients with cataract who were randomly assigned either to have phacoemulsification with the fluid-based system (30 eyes of 30 patients--Group 1) or with traditional ultrasound (30 eyes of 30 patients--Group 2). Patients who were available at each follow-up visit (25 eyes in both groups) were enrolled in the statistical analysis. Endothelial function was evaluated by measuring central corneal thickness, central endothelial cell density (ECD), mean cell size, and coefficient of variation in cell size preoperatively, 10 days, 1 and 3 months, and 1 year after surgery. Statistical analyses were performed using two-way repeated measure ANOVA.

RESULTS

An acute, reversible increase of central corneal thickness (CCT) was found 10 days after surgery, which was similar in both groups (P=0.35). ECD decreased, whereas mean cell size increased significantly immediately after surgery. However, the impairments were finished after 1 month. The alterations were similar in both groups (ECD: P=0.99; mean cell size: P=0.85). The coefficient of variation in cell size remained stable after surgery (P=0.08), and significant difference was not found between groups (P=0.99). The endothelial cell loss (ECL) was 6.5+/-8.4% in Group 1 and 6.5+/-11.7% in Group 2 (P=0.69).

CONCLUSIONS

Corneal endothelial changes were similar using the fluid-based system compared to the traditional ultrasound technique. The fluid-based method proved to be as safe as conventional ultrasound in cataract surgery.

Cataract surgery in Fuchs?? dystrophy

PURPOSE OF REVIEW

Corneal decompensation after cataract surgery can occur in patients with Fuchs' endothelial dystrophy. This paper reviews the pathogenesis of corneal edema in Fuchs' dystrophy, the preoperative and perioperative risk factors for corneal endothelial cell loss during cataract surgery, and indications for cataract surgery alone or cataract surgery combined with keratoplasty for patients with visually significant cataracts and Fuchs' dystrophy.

RECENT FINDINGS

Accelerated loss of corneal endothelial cells in Fuchs' dystrophy is multifactorial, with apoptosis and altered gene regulation of aquaporin proteins playing a role. Preoperative factors contributing to decreased endothelial cell count include age, sex, diabetes, a history of ocular trauma or inflammation, and contact lens wear. Intra-operative measures shown to protect endothelial cells include the use of the soft-shell viscoelastic technique for very dense cataracts, efficient cataract removal techniques (phaco-chop, use of oscillatory handpiece), and surgery by an experienced surgeon. A triple procedure should be performed with preoperative corneal epithelial decompensation and considered with preoperative pachymetry greater than 640 mum. Otherwise, it is reasonable to attempt cataract surgery alone with proper patient education.

SUMMARY

Fuchs' dystrophy is a progressive disorder. Cataract surgery in the setting of Fuchs' dystrophy can be performed successfully, especially when the surgeon is aware of the preoperative and intraoperative factors that affect the number of functioning endothelial cells. All patients should be aware of the progressive nature of this disease and the possibility of keratoplasty at some point in their lifetime.