Experimental anterior chamber maintenance in active versus passive phacoemulsification fluidics systems

Research progress on the impact of cataract surgery on corneal endothelial cells

Background

Cataracts are a common eye disease and a major cause of blindness in China and worldwide. In China, the incidence of cataracts among people over 60 years old is as high as 80%. Surgery is the primary treatment for various types of cataracts, but such invasive procedures can affect corneal endothelial cells to some extent.

Content

Cataract surgery can damage corneal endothelial cells, leading to complications such as corneal edema in mild cases. Severe damage can result in endothelial decompensation, necessitating secondary corneal endothelial transplantation. Preoperative thorough assessment of endothelial status, intraoperative endothelial protection measures, and postoperative active use of medications to prevent further damage to endothelial cells can reduce endothelial cell loss. Factors influencing endothelial cell status include whether the patient has related systemic diseases or ocular conditions, the hardness of the nucleus, the choice of surgical incision, the method of nuclear fragmentation, the type of viscoelastic agent used, the orientation of the phacoemulsification needle bevel, the duration and energy of ultrasound use, the choice of fluid control system, the use of protective auxiliary instruments, the application of intraocular lens scaffold technology, femtosecond laser assistance, and the use of certain medications.

Conclusions

Actively regulating the factors affecting corneal endothelial cells to reduce damage related to cataract surgery is crucial. This paper reviews the existing literature on various factors affecting corneal endothelial cells during cataract surgery and explores future developments and research directions.

Safety and prognosis of phacoemulsification using active sentry and active fluidics with different IOP settings - a randomized, controlled study

PURPOSE

To explore the impact of different intraoperative intraocular pressure (IOP) settings on the safety and prognosis in phacoemulsification.

METHODS

Age related cataract patients who met the inclusion criteria and underwent phacoemulsification by using active sentry handpiece and active fluidics system. According to different intraoperative IOP settings during surgery, they were randomly divided into two groups: the 20mmHg group and the 60mmHg group. The best corrected visual acuity (BCVA), cumulative dissipated energy (CDE), total U/S time, active surge mitigation (ASM), estimated fluid usage (EFU) as well as the changes in corneal thickness (CT), corneal epithelial layer thickness (CELT) and endothelial cell density (ECD) were collected. The post-operative follow-up was only 1 day.

RESULTS

A total of 110 cases (110 eyes) were included in the study. There were 55 eyes in each group. There was no statistically significant difference in postoperative BCVA (p = 0.839). The CDE, total U/S time and EFU during surgery were (5.22 ± 3.31), (30.60 ± 15.06), (45.07 ± 12.68) and (4.70 ± 2.83), (27.39 ± 13.75), (42.38 ± 11.93) in the 20mmHg group and 60mmHg group (p = 0.381, 0.246, 0.254). The ASM during surgery in the 20mmHg group and 60mmHg group were (0.95 ± 2.77) and (7.24 ± 6.34), respectively. The 20mmHg group showed a significant decrease in ASM (p < 0.001). There was no statistically significant difference in the changes in CT, CELT and ECD before and after surgery between the two groups (p = 0.913, 0.825, 0.624). Both groups did not experience any intraoperative complications, such as posterior capsule rupture.

CONCLUSION

A lower IOP setting of 20 mmHg can significantly reduce the occurrence of intraoperative surges during phacoemulsification. And there was no increase in rate of complications.

TRIAL REGISTRATION

The trial registration number is ChiCTR2100050240. The registered date is August 24th, 2021.

Phacoemulsification using an active fluidics system at physiologic vs high intraocular pressure: impact on anterior and posterior segment physiology

PURPOSE

Evaluate the impact of high vs low intraoperative intraocular pressure (IOP) during phacoemulsification on anterior and posterior physiology.

SETTING

Private practice in Des Moines, Iowa.

DESIGN

Prospective, randomized, paired-eye clinical trial of patients anticipating bilateral cataract surgery.

METHODS

27 participants randomized at the time of their first cataract surgery to either low IOP or high IOP group. The subsequent cataract surgery was performed under the alternate condition. During phacoemulsification and cortex removal, IOP was maintained either at low (≤28 mm Hg) or at high (≥55 to 60 mm Hg) levels. The primary outcome was fluid usage, with secondary outcomes of central corneal thickness, foveal avascular zone area, foveal and macular thickness, endothelial cell density (ECD), and postoperative inflammation.

RESULTS

Surgery with low IOP settings used less fluid (40.0 mL vs 55.6 mL, P < .0001). Corneal thickness changes were smaller in low IOP eyes at 1 day and 1 week (3.0% vs 8.1%, P = .01; 3.1% vs 4.4%, P = .01) but were similar by 1 and 3 months. ECD dropped less in low IOP eyes at 1 and 3 months (-1.7% vs -12.3%, P = .001, 2.1% vs -8.9%, P = .0003.) IOP remained a significant predictor of ECD change when relationship was controlled for fluid use and phacoemulsification energy. Retinal parameters did not vary among all eyes or when compared by IOP setting. Visual acuity was similar at all timepoints.

CONCLUSIONS

Low IOP settings resulted in less inflammation and less corneal trauma, as evidenced by a smaller drop in ECD and less postoperative corneal edema, when compared with high IOP settings. Retinal parameters did not change significantly. The different outcomes did not result in a difference in visual acuity.

Intraoperative Performance and Early Postoperative Outcomes Following Phacoemulsification With Three Fluidic Systems: A Randomized Trial

PURPOSE

To compare intraoperative performance and early postoperative outcomes following phacoemulsification with two systems using active fluidics and one using gravity-based fluidics.

METHODS

In this prospective randomized trial, 200 eyes were randomized to the traditional and Active Sentry groups (n = 80 eyes each) where the Centurion Vision System was used with traditional or Active Sentry (Alcon Laboratories, Inc) hand-pieces, respectively, or the Infinit group (n = 40 eyes) where the Infiniti Vision System (Alcon Laboratories, Inc) was used. Within the traditional and Active Sentry groups, there were two subgroups with low (30 mm Hg) or high (55 mm Hg) intraocular pressure (IOP) used. Outcome measures compared were: cumulative dissipated energy (CDE), percentage change in central corneal thickness (CCT) at 1 day, 1 week, and 1 month, anterior chamber cells at 1 day and 1 week, rate of rise and fall of IOP following occlusion break, corneal endothelial cell density (ECD), and macular thickness 6 months postoperatively.

RESULTS

CDE was significantly lower in group II compared to the traditional group (2.96 ± 1.4 vs 4.14 ± 2.2, P = .001). With 30 mm Hg IOP, the Active Sentry group had significantly less percentage change in CCT at 1 week postoperatively compared to the traditional handpiece group (0.01% vs 0.02%, P = .008). Incidence of anterior chamber cells less than grade 2 on day 1 was significantly higher in the Active Sentry group (82.9% vs 52%, P = .03). Percentage change in ECD was significantly lower in the Active Sentry group (-0.957 vs -0.98%, P = .005). Significantly faster rise of IOP to baseline following occlusion break was seen in the Active Sentry group.

CONCLUSIONS

The use of Active Sentry handpiece was associated with lower CDE, less postoperative increase in CCT, fewer anterior chamber cells, and faster rise of IOP following occlusion break. [J Refract Surg. 2024;40(5):e304-e312.].

Effect and Safety of Pressure Sensor-equipped Handpiece in Phacoemulsification System

PURPOSE

To evaluate the effect of the Active Sentry handpiece of the Centurion Vision System compared to the Centurion Ozil handpiece for phacoemulsification in cataract surgery.

METHODS

A retrospective study was conducted on 281 patients (449 eyes) who underwent cataract surgery between August 2020 and June 2021. Preoperative measurements, intraoperative parameters, complication rate, and postoperative outcomes were compared between the Active Sentry handpiece and the Centurion Ozil handpiece groups. Additionally, the parameters were compared in different cataract severity groups and multiple predictive factors for the number of active surge mitigation (ASM) actuations were assessed with the Active Sentry handpiece.

RESULTS

There were 198 eyes in the Active Sentry group and 251 eyes in the Centurion Ozil group. There were no statistically significant differences between the two groups, as the cumulative dissipated energy in the Active Sentry and Centurion Ozil groups were 8.32 ± 7.74 and 7.87 ± 9.25 μJ, respectively (p = 0.576). Total surgery time, ultrasound usage time, aspiration time, amount of fluid aspirated, postoperative corrected distant visual acuity, and postoperative decrease in corneal endothelial cell density were comparable between the two groups. The significant contributors to the number of ASM actuations were age, preoperative corrected distant visual acuity, axial length, and total ultrasound time.

CONCLUSIONS

There was no clear advantage of the Active Sentry handpiece compared to the Centurion Ozil handpiece. ASM actuation increases with age, poor visual acuity before surgery, short axial length, and prolonged ultrasound usage time. It is expected that in more severe and high-risk cataract surgery, the Active Sentry handpiece functions more effectively, possibly affecting the safety and prognosis.

Experimental study comparing 2 different phacoemulsification systems with intraocular pressure control during steady-state flow and occlusion break surge events

PURPOSE

To compare peak surge and surge duration time after occlusion break, incision leakage compensation, and passive vacuum for 2 phacoemulsification systems.

SETTING

Carl Zeiss Meditec AG, Oberkochen, Germany.

DESIGN

Laboratory study.

METHODS

A spring-eye model was used to test Alcon Centurion Vision and Zeiss Quatera 700 systems. Peak surge and duration was measured after an occlusion break. Quatera tested in flow and vacuum priority modes. Vacuum limits ranged from 300 to 700 mm Hg with intraocular pressure (IOP) set at 30 mm Hg, 55 mm Hg, and 80 mm Hg. IOP vs incision leakage rates of 0 to 15 cc/min and passive vacuum were measured.

RESULTS

At 30 mm Hg IOP set point and vacuum limits ranging 300 to 700 mm Hg, the surge duration time after occlusion break ranged 419 to 1740 milliseconds (ms) for Centurion, 284 to 408 ms for Quatera in the flow mode, and 282 to 354 ms for Quatera in the vacuum mode. At 55 mm Hg, values ranged 268 to 1590 ms for Centurion, 258 to 471 ms for Quatera in the flow mode, and 239 to 284 ms for Quatera in the vacuum mode. At 80 mm Hg, values were 243 to 1520 ms for Centurion, 238 to 314 ms for Quatera in the flow mode, and 221 to 279 ms in the vacuum mode. Centurion exhibited slightly less peak surge than the Quatera. At 55 mm Hg: incision leakage rates 0 to 15 cc/min, Quatera held the IOP within ±2 mm Hg of target; Centurion was unable to hold IOP target allowing a 11.7 mm Hg decrease with 32% higher passive vacuum.

CONCLUSIONS

Quatera demonstrated slightly higher surge peak values and notably shorter surge duration times after occlusion break than Centurion. Quatera demonstrated better incision leakage compensation and lower passive vacuum than Centurion.

Application of the Active-Fluidics System in Phacoemulsification: A Review

The fluidics system is an indispensable and primary component of phacoemulsification. Both the gravity-fluidics system and active-fluidics system are commonly used in practice. The irrigation pressure of the gravity-fluidics system is determined by the bottle height, which is relatively constant, while the active-fluidics system is paired with a cassette that contains pressure sensors to monitor intraocular pressure changes. The active-fluidics system allows surgeons to preset a target intraocular pressure value, and it replenishes the fluids proactively; thus, the intraocular pressure is consistently maintained near the target value. Under such circumstances, stable intraocular pressure and anterior chamber volume values could be acquired. Research on surgical safety, efficiency and results have reported several strengths of the active-fluidics system. It is also advantageous in some complicated cataract surgeries. However, the system is not widely used at present, mainly due to its low penetration rate and high equipment cost. Some of its updates such as the new Active Sentry handpiece showed potential superiority in laboratory studies recently, but there is still further research to be conducted. This article gives an overview of the mechanism and performance of the active-fluidics system, and it is expected to provide clues for future research.

Effect of a new phacoemulsification and aspiration handpiece on anterior chamber stability

PURPOSE

To evaluate the responsiveness of 3 phacoemulsification and aspiration (PEA) systems and a new handpiece to occlusion break by measuring anterior chamber depth (ACD) and intraocular pressure (IOP).

SETTING

Zengyo Suzuki Eye Clinic, Kanagawa, Japan.

DESIGN

Experimental study.

METHODS

ACD change during intentional occlusion breaks was observed and evaluated using the slit side view (SSV) method and IOP measurement with the Centurion Vision System (Group 1), Centurion Vision System with Active Sentry (Group 2), Infiniti Vision System (Group 3), and Constellation Vision System (Group 4). 5 eyes were included per group. Occlusion breaks were triggered at IOP of 30 mm Hg, vacuum limits of 550 mm Hg, and aspiration rate of 40 mL/min. ACD change ratio, surge duration, and surge volume were analyzed from videos of SSV and IOP measurement.

RESULTS

The smallest ACD change was observed in Group 2 with SSV. ACD change ratios in Groups 1 to 4 were 17.5% ± 3.9%, 7.3% ± 1.2%, 35.7% ± 9.5%, and 74.1 ± 7.7%, respectively. Surge duration and surge volume were calculated only for Groups 1 and 2 and were significantly lower in Group 2 than in Group 1 (0.32 ± 0.03 vs 1.17 ± 0.07 seconds; 18.91 ± 4.70 vs 45.70 ± 0.83 μL). In these 2 groups, ACD change ratio correlated with surge volume.

CONCLUSIONS

This study evaluated the responsiveness of 3 PEA systems and a new handpiece to occlusion breaks by measuring IOP and ACD. The Active Sentry system was useful for maintaining the ACD even during occlusion breaks.

Torsional Power and Tip Shape Greatly Change Irrigation Flow Feeding Rate

BACKGROUND

It is important to maintain intraocular pressure during cataract surgery. When the intraocular pressure sharply drops during phacoemulsification, it is important to ensure a compensatory maximum fluid supply. To the best of our knowledge, this is the first study presenting the maximum irrigation flow supply using an ultrasonic tip shape and torsional power setting.

METHODS

The weight of BSS PLUS 500 ejected during torsional oscillation fitted with a mini-tip or balanced tip and nano sleeve with IOP set at 20 mmHg (IOP20) or 40 mmHg (IOP40) was measured. The weight of the BSS ejected from the sleeve over 3.0 s (15 measurements taken at 200-ms intervals) was measured to calculate the irrigation flow feeding rate. Measurements were made four times at each torsional power setting (TP).

RESULTS

With a balanced tip, the irrigation flow rate rose as TP was increased, whereas, at 60% or 90% TP, the irrigation flow rate markedly decreased. With the mini-tip, the irrigation flow rate remained relatively stable, up to 60% or 80% TP but decreased dramatically at higher power settings. Compared with IOP20, the irrigation flow rate increased by 1.21- to 1.28-fold with the balanced tip and by 1.28- to 1.41-fold with the mini-tip at IOP40. At IOP20, the irrigation flow rate was higher with the mini-tip at 0% and 5% TP but equal to or higher with the balanced tip at TP of ≥10%. At IOP40, the irrigation flow rate with the mini-tip was equal to or higher than that with the balanced tip at all TP.

CONCLUSIONS

The irrigation flow rate tends to vary with changes in TP and tip shape.

A prospective randomized clinical trial of active-fluidics versus gravity-fluidics system in phacoemulsification for age-related cataract (AGSPC)

BACKGROUND

To figure out the efficacy, effects, safety and patient's subjective perceptions of phacoemulsification with the active-fluidics system (AFS).

PATIENTS AND METHODS

This was a prospective, randomized, double-masked, controlled clinical study. Age-related cataract patients were recruited and randomly assigned to the AFS group and gravity-fluidics system (GFS) group in a ratio of 1:1 to have phacoemulsification. Participants were followed up at one day, one week, one month and three months postoperatively (Chinese Clinical Trial Registry, ChiCTR2100044409).

RESULTS

The overall included participants were 107 finally. The total aspiration time of the AFS group was significantly less than that of the GFS group (p = .020), while no significant difference existed in cumulative dissipated energy and estimated fluid usage between the two groups. The best corrected visual acuity was significantly better in the AFS group at one day and one week postoperatively (p = .002, p = .038 respectively). The recovery of central corneal thickening and macular superficial vasculature increase was earlier in the AFS group. The central retinal thickness was significantly higher in the GFS group at one month and three months postoperatively (p = .029, p = .016 respectively). The incidence of corneal adverse events was higher in GFS group (p = .035). No serious adverse events occurred in either group. Pain scores and the scores of Cat-PROM5 questionnaire of the AFS group were significantly lower than that of the GFS group (p = .011, p = .002 respectively).

CONCLUSION

AFS improves the efficiency, effects, safety and patients' subjective perceptions of phacoemulsification compared with GFS. It is worthwhile to promote its application in cataract surgery.KEY MESSAGESThe active-fluidics system automatically detects and maintains stable intraocular pressure at the set value.The active-fluidics system improves the efficiency, effects, safety and patients' subjective perceptions in phacoemulsification.

Clinical Outcomes of Applying Therapeutic Contact Lenses and Eye Drops after Cataract Surgery

Purpose: To investigate the safety of applying therapeutic contact lenses and eye drops after cataract surgery.Methods: Immediately after cataract surgery, 947 eyes (group 1) used therapeutic contact lenses and eye drops and 914 (group 2) applied antibiotic ointment and wore a gauze eye patch for the first postoperative day. Clinical outcomes including best corrected visual acuity (BCVA), IOP, degree of anterior chamber inflammation, wound leakage, and postoperative endophthalmitis were compared in the two groups 1 day, 1 week, and 1 month after surgery.Results: There were no significant differences in the mean pre- and postoperative BCVA and IOP at 1 day, 1 week, and 1 month between groups 1 and 2. There was no difference in anterior chamber inflammation between the two groups at 1 day (p = 0.302), 1 week (p = 0.437), or 1 month (p = 0.960) after surgery. On the first postoperative day, 10 eyes in group 1 and nine eyes in group 2 had wound leakage (p = 1.000). There was no endophthalmitis in either group.Conclusions: The risk of postoperative complications in group 1 was not higher than in group 2. Therefore, wearing therapeutic contact lenses and using eye drops is a relatively safe management method after cataract surgery.

Active-fluidics versus gravity-fluidics system in phacoemulsification for age-related cataract (AGSPC): study protocol for a prospective, randomised, double-blind, controlled clinical trial

INTRODUCTION

The active-fluidics system is a new irrigation system of phacoemulsification that automatically detects and maintains stable intraocular pressure at the set value. This trial is designed to compare the efficacy, visual outcomes, safety and patients' subjective perceptions of cataract surgery with the active-fluidics system and gravity-fluidics system.

METHODS AND ANALYSIS

This trial will recruit 110 patients with age-related cataract at the Chinese People's Liberation Army (PLA) General Hospital (Beijing, China) and they will be randomly assigned to the active-fluidics group and gravity-fluidics group in a ratio of 1:1 to have phacoemulsification. Patients will be followed up at 1 day, 1 week, 1 month and 3 months postoperatively. The primary outcomes are the cumulative dissipated energy and best corrected visual acuity. Secondary outcomes include: estimated fluid usage, U/S time, total aspiration time, intraocular pressure, corneal endothelium parameters, retinal thickness, macular superficial vessel density, pain scores, scores of the Cataract surgery Patient-Reported Outcome Measures Questionnaire and the complication rates. The data will be independently analysed by the statistical team, who will be masked for the allocation information as participants are.

ETHICS AND DISSEMINATION

This study was approved by the Ethics Committee of Chinese PLA General Hospital (approval no. S2021-068-01). Informed consent will be obtained from each participant. All the results will be published in peer-reviewed journals and used for scholarly communication or technical guidance. Protocol version 1.0.

TRIAL REGISTRATION NUMBER

Chinese Clinical Trial Registry (ChiCTR2100044409).

Efficient use of ultrasound in cataract surgery

PURPOSE OF REVIEW

Modern phacoemulsification machines apply ultrasound through a variety of settings and parameters to remove a cataract. Using these new technologies efficiently is critical for both reducing surgical times and improving postoperative outcomes. The present article reviews recent findings in phacodynamics to explore the optimum use of ultrasound in cataract surgery.

RECENT FINDINGS

In studies seeking to determine the optimum parameters in both fluidics and power, increased power and aspiration does not necessarily equate to more efficiency. New developments, such as torsional ultrasound, micropulse, and burst mode have shown increased efficiency in randomized control trials and in-vitro compared with conventional ultrasound. Regarding vacuums, the venturi pump has demonstrated greater efficiency compared with the peristaltic pump. We also explore other parameters, such as chamber pressure and tip selection. Meta-analyses on femtosecond-laser assisted cataract surgery (FLACS) have shown similar long-term visual outcomes compared to conventional cataract surgery.

SUMMARY

Though conventional cataract surgery remains highly effective, surgeons have increasing options for customizing their ultrasound settings and phacoemulsification techniques.

Real-time dynamic changes in intraocular pressure after occlusion break: comparing 2 phacoemulsification systems

PURPOSE

To compare real-time intraocular pressure (IOP) response to occlusion break event in 2 phacoemulsification systems.

SETTING

Iladevi Cataract and IOL Research Center, India.

DESIGN

Randomized, experimental study.

METHODS

Rabbits were randomized to:Group I (n = 10 eyes), Centurion Vision system with active fluidics, or, Group II (n = 10 eyes), Centurion with Active Sentry. Within each group, parameter set 1 (IOP 30 mm Hg, aspiration flow rate [AFR] 20 mL/min, and vacuum 600 mm Hg) and parameter set 2 (IOP 50 mm Hg, AFR 25 mL/min, and vacuum 600 mm Hg) were tested. Real-time rate of drop and rise of IOP after occlusion break event (mm Hg per second) and percentage reduction of IOP from maximum during nuclear fragment removal were compared.

RESULTS

10 rabbits (20 eyes) were included. Rate of drop of IOP after occlusion break was not significantly different between groups. Rate of rise of IOP was statistically significantly higher in Group II with both parameter sets (199.09 ± 69.28 vs 94.33 ± 45.66 in parameter set 1, P = .006; and 256 ± 45.05 vs 165.25 ± 51.80 in parameter set 2, P = .005), suggesting faster recovery to baseline IOP after occlusion break. The mean percentage reduction of IOP from maximum was significantly higher in Group I (P = .003).

CONCLUSIONS

Rise of IOP to baseline after occlusion break event was faster and mean percentage reduction of IOP from maximum during nuclear fragment removal was lower when using the Centurion Vision system with the Active Sentry upgrade compared with the traditional handpiece. The ability to sense IOP at the level of the handpiece with the Active Sentry upgrade allows faster mitigation of surge response.

Active sentry versus ozil hand piece - A prospective randomized comparative study

PURPOSE

To compare the safety and efficacy of active sentry hand piece with ozil hand piece for centurion phacoemulsification system.

SETTING

Tertiary eye centre, South India.

DESIGN

Prospective observational study.

METHODS

A total of 204 eyes of 204 patients with uncomplicated cataract who underwent phacoemulsification cataract surgery with centurion vision system were randomized into two groups: Ozil hand piece (n=101) and active sentry hand piece (n =103). Intra-operative factors like patient's pain perception, surgeon's comfort level, amount of phacoemulsification energy and aspiration fluid used, frequency of activation of active surge mitigation (ASM) were analyzed and post-operatively corrected distance visual acuity (CDVA) and corneal edema on day one were compared.

RESULTS

Patient's pain perception was comparable between the groups with no significant differences in proportion of patients who had pain free surgery (66% vs 61.3%) or those experienced moderate pain (24.3% vs 28.7%). Surgeons were more comfortable using ozil hand piece during entry into anterior chamber and emulsification of hard nuclei (48.5% vs 28.6%). The mean CDE for soft cataracts was 5.6 and 4.8 and for hard cataracts it was 9.3 and 9.4 for ozil and active sentry group respectively. ASM was activated for 53 (51.5%) eyes, of which 42 (79.2%) eyes had soft cataract and 11 (20.7%) had hard cataract. Post-operative CDVA and incidence of corneal edema was comparable between the groups.

CONCLUSION

For centurion vision system, active sentry hand piece is safe and efficacious as the ozil hand piece with added benefit of operating at lower IOP levels.

Early changes in retinal microcirculation after uncomplicated cataract surgery using an active-fluidics system

PURPOSE

To evaluate the early changes in retinal microcirculation after uncomplicated cataract surgery using an active-fluidics system.

MATERIALS AND METHODS

Patients underwent uncomplicated cataract surgery for both eyes were enrolled. The two eyes of the patients were randomly assigned to two groups, the active-fluidics group and the gravity-fluidics group. One eye using an active-fluidics system, and the other using a gravity-fluidics system. Optical coherence tomography angiography (OCTA) was performed at 1 day, 7 days, 30 days, and 90 days after surgery.

RESULTS

Fifty eyes (25 patients) were included in the final analysis. A significantly lower cumulative dissipated energy (CDE), estimated fluid usage (EFU), and total aspiration time (TAT) were observed in the active-fluidics group (all P<0.05). The superficial vessel density at parafoveal region increased at 7 days and 30 days after cataract surgery in the eyes of both the active-fluidics and gravity-fluidics groups, with the fluctuation in eyes of the gravity-fluidics group more significant. The vessel density of deep capillary plexus remained stable during the follow-up period. Significant changes of retinal thickness in macular region (fovea, parafovea) were observed in eyes of the gravity-fluidics group through the comparison of corresponding values at different time points (p = 0.008, 0.005). No significant change in retinal thickness was observed in eyes of the active-fluidics.

CONCLUSIONS

Retinal microcirculation and thickness were disturbed after cataract surgery using the gravity-fluidics infusion system. The active-fluidics system not only improved the surgical efficacy but also protected the retinal vasculature during cataract surgery.

CLINICAL TRIALS REGISTRATION

The study has been registered at www.clinicaltrials.gov with its clinical trial accession number of NCT0130500.

Elevated intraocular pressure causes cellular and molecular retinal injuries, advocating a more moderate intraocular pressure setting during phacoemulsification surgery

PURPOSE

To evaluate the cellular and molecular retinal injuries induced by various intraocular pressure (IOP) settings in a mouse model of acute ocular hypertension (AOH), and to advise using a more moderate target IOP during phacoemulsification (phaco) surgery.

METHODS

A mouse model of AOH that mimics a transient IOP elevation during phacoemulsification cataract surgery was established. Six groups with various settings of target IOP were included. Retinal tissues were assessed with terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end-labeling (TUNEL) staining for neuron loss, immunofluorescence with Iba1 for microglia activation, and quantitative real-time polymerase chain reaction analysis with tight junction proteins (claudin-3 and claudin-5) or classic inflammation markers (IL-1β and eNOS) for impairment of the blood-retinal barrier (BRB) and inflammatory injury.

RESULTS

Compared with those in the 45-mmHg IOP group, significantly increased number of neurons loss and increased microglia activation were observed in 90-mmHg IOP group. In addition, the expression of claudin-3 and claudin-5 was significantly decreased, while the expression of IL1-β and eNOS was up-regulated, indicating impairment of the BRB and inflammatory injury in the retina. Furthermore, these findings of neuron loss, microglia activation, and inflammation in the 90-mmHg groups were exacerbated when an IOP-induced retinal injury was established 5 days earlier, while those in the 45-mmHg groups remained almost unchanged.

CONCLUSIONS

In conclusion, these results showed that a relatively commonly used high IOP setting (90 mmHg) could induce significantly more serious retinal injury. An IOP setting around 45 mmHg is relatively safe and might be recommended in phaco surgery, especially in patients with advanced glaucoma, previous acute angle closure crisis, or other diseases with fragile retina and optic nerve.

Intraoperative intraocular pressure fluctuation during standard phacoemulsification in real human patients

INTRODUCTION

To evaluate the results of the fluctuations of intraocular pressure (IOP) and calculated mean ocular perfusion pressure (MOPP) during the usual steps of standard phacoemulsification.

METHODS

Nine human eyes were evaluated. The IOP was measured indirectly by electronic applanation tonometer. The MOPP was calculated using the systolic blood pressure (SBP), the diastolic blood pressure (DBP) and the IOP: MOPP = 2/3x[DBP + 1/3x(SBP - DBP)] - IOP. The operations were performed with the INFINITI^® Vision System: main incision 2.2 mm, coaxial handpiece, 2 paracenteses 1.1 mm, bimanual irrigation/aspiration, bottle height 100 cm. As ocular viscoelastic device (OVD) Hypromel 2.5% (UNIMED) was used.

RESULTS

The initial and final IOPs were 17-30 Torr (median 18) and 6-16 Torr (median 8), respectively. The IOP values oscillated between 4 and 63 Torr during the procedure. The highest values of the IOP were achieved at the beginning of phacoemulsification (from 42 to 63 Torr). The maximum pressure higher than 50 mmHg and 60 mmHg was found in 89% and 30% of cases, respectively. The mean ocular perfusion pressure (MOPP) at the beginning of the procedure was 46.4-67.0 (median 53.3) and 0.4-42.0 (median 19.3) during the maximum intraocular pressure.

CONCLUSIONS

Measured IOP as well as MOPP varied in all normal steps of real phacoemulsification. High values of intraoperative IOL induced by irrigation may compromise the intraocular perfusion. These fluctuations may induce impairment of the optic nerve perfusion, as well as retina, or choroid.

Comparative Analysis of One-Handed and Two-Handed Coaxial Phacoemulsification with 2.4-mm Clear Corneal Incision

PURPOSE

To compare the efficiency and safety of one-handed and two-handed coaxial phacoemulsification Material and Methods: Patients with cataracts underwent one-handed (one-handed group) or two-handed coaxial phacoemulsification (two-handed group) with a 2.4-mm clear corneal incision. Intraoperative phaco parameters, total surgical time, postoperative visual acuity, surgically induced astigmatism (SIA), corneal volume (CV), central corneal thickness (CCT) and corneal endothelial cell counts/size were compared between the two groups.

RESULTS

Each group comprised 105 eyes. There were no significant differences in the intraoperative phaco parameters and total surgical time between the two groups (all p > 0.05). Visual outcomes were significantly better in the one-handed group than in the two-handed group 1 week postoperatively (all p< 0.05) but not 1 month postoperatively. There was no significant difference in SIA between the two groups 1 week (p = 0.695) or 1 month postoperatively (p = 0.772). CV, CCT and endothelial cell loss were significantly lower in the one-handed group than in the two-handed group 1 week postoperatively (CV: p = 0.004; CCT: p = 0.046; endothelial cell loss: p = 0.021), but the above differences were absent 1 month postoperatively except for endothelial cell loss (endothelial cell loss: p = 0.038).

CONCLUSIONS

Both one-handed and two-handed coaxial phacoemulsification were effective and safe surgical techniques. However, the one-handed technique had the advantages of less trauma to the cornea and better early clinical outcomes than the two-handed technique for cataract patients within nuclear opalescence (NO) 3 grade ≤ 3.

Comparative studies between longitudinal and torsional modes in phacoemulsification, using active fluidics technology along with the intrepid balanced tip

Purpose:

To compare and report the intra- and postoperative outcomes of phacoemulsification between longitudinal (LPKE) and torsional (TPKE) mode, using active fluidics along with the intrepid balanced tip.

Methods:

This single center prospective randomized comparative study comprised a total 108 consecutive eyes of 108 patients having senile cataract subdivided into nuclear opalescence (NO) grades II–IV according to the lens opacities classification system III (LOCS III). Cataracts of each grade were randomly assigned to two groups LPKE (n = 54) and TPKE (n = 54) mode, who were operated on by the same surgeon using same machine (Centurion^® Alcon Laboratories, Inc., USA) having features of both active fluidics and intrepid balanced tip. Pre-, intra-, and postoperative evaluations were done independently by a different author, who was masked to the surgical procedures. Patients were evaluated on the postoperative days (PODs) 1, 7, 15, and 28. Intraoperative outcome measures were cumulative dissipated energy (CDE) and ultrasound time (UST). Postoperative outcome measures were endothelial cell loss (ECL), central corneal thickness (CCT), and best-corrected visual acuity (BCVA).

Results:

Age, gender, and NO-grade distribution among two modes were comparable (P > 0.05). Difference of CDE and UST between modes were found to be significant (P < 0.001) in favor of TPKE with all NO-grades. TPKE mode performs better than LPKE mode with regard to ECL, CCT-change, and BCVA-change, although the differences were found to be insignificant (P > 0.05).

Conclusion:

When using active fluidics along with the intrepid balanced tip, TPKE mode appeared to be a more efficient mode of PKE with reduced mean UST and CDE across all NO-grades, as compared to LPKE mode. However, ECL, CCT-change, and BCVA-change were seemed to be comparable between the two modes.

Mechanical model of human eye compliance for volumetric occlusion break surge measurements

PURPOSE

To develop a mechanical model of human eye compliance for volumetric studies.

SETTING

Alcon Research, Ltd., Lake Forest, California, USA.

DESIGN

Experimental study.

METHODS

Enucleated human eyes underwent pressurization and depressurization cycles with peak intraocular pressures (IOPs) of 60 to 100 mm Hg; anterior chamber pressure and volume changes were measured. Average net volume change curves were calculated as a function of IOP for each eye. Overall mean volumes were computed from each eye's average results at pressure points extrapolated over the range of 5 to 90 mm Hg. A 2-term exponential function was fit to these results. A fluid chamber with a displaceable piston was created as a mechanical model of this equation. A laser confocal displacement meter was used to measure piston displacement. A test bed incorporated the mechanical model with a mounted phacoemulsification probe and allowed for simulated occlusion breaks. Surge volume was calculated from piston displacement.

RESULTS

An exponential function, V = C₁ × exp(C₂ × IOP) + C₃ × exp(C₄ × IOP) - V₀, where V, the volume, was fit to the final depressurization curve obtained from 15 enucleated human eyes. The C₁ through C₄ values were -0.07141, -0.23055, -0.14972, and -0.02006, respectively. The equation was modeled using a piston system with 3 parallel springs that engaged serially. The mechanical model mimicked depressurization curves observed in human cadaver eyes.

CONCLUSION

The resulting mechanical compliance model measured ocular volumetric changes and thus would be helpful in characterizing the postocclusion break surge response.

Prospective study of Centurion® versus Infiniti® phacoemulsification systems: surgical and visual outcomes

AIM

To evaluate surgical outcomes (SOs) and visual outcomes (VOs) in cataract surgery comparing the Centurion^® phacoemulsification system (CPS) with the Infiniti^® phacoemulsification system (IPS).

METHODS

Prospective, consecutive study in a single-site private practice. Totally 412 patients undergoing cataract surgery with either the CPS using the 30-degree balanced^® tip (n=207) or the IPS using the 30-degree Kelman^® tip (n=205). Intraoperative and postoperative outcomes were documented prospectively up to one month follow-up. Nuclear sclerosis (NS) grade, cumulated dissipated energy (CDE), preoperative corrected distance visual acuity (CDVA), and CDVA at one month were recorded.

RESULTS

CDE was 13.50% less in the whole CPS compared with the whole IPS subcohort. In eyes with NS grade III or greater, CDE was 28.87% less with CPS (n=70) compared with IPS (n=44) (P=0.010). Surgical complications were not statistically different between the two subcohorts (P=0.083), but in the one case of vitreous loss using the CPS, CDVA of 6/4 was achieved at one month. The mean CDVAs (VOs) at one month for NS grade III and above cataracts were -0.17 logMAR (6/4.5) in the CPS and -0.15 logMAR (6/4.5) in the IPS subcohort respectively (P=0.033).

CONCLUSION

CDE is 28.87% less, and VOs are significantly improved, in denser cataracts in the CPS compared with the IPS. The authors recommend the CPS for cases with denser nuclei.

Effect of IOP based infusion system with and without balanced phaco tip on cumulative dissipated energy and estimated fluid usage in comparison to gravity fed infusion in torsional phacoemulsification

Background

To evaluate the effect of three different combinations of tip designs and infusion systems in torsional phacoemulsification (INFINITI and CENTURION) in patients with cataract. According to the manufacturer, two unique improvements in the Centurion are: active fluid dynamic management system and use of an intrepid balanced tip. The study specifically aimed to evaluate the beneficial effects, if any, of change in tip design and infusion system individually and in combination on both per-operative parameters as well as endothelial health over 6 months.

Methods

One hundred and twenty six consenting patients of grade 4.0–6.9 senile cataract were randomized into three groups for phacoemulsification: Group A (n = 42): Gravity fed infusion system and 45⁰ Kelman miniflared ABS phaco tip; Group B (n = 42): intraocular pressure (IOP) based infusion system and 45⁰ Kelman miniflared ABS phaco tip; Group C (n = 42): IOP based infusion system and 45⁰ Intrepid balanced phaco tip. The cumulative dissipated energy (CDE), estimated fluid usage (EFU) and total aspiration time (TAT) were compared peroperatively. The endothelial parameters were followed up postoperatively for six months.

Results

The three arms were matched for age (p = 0.525), gender (p = 0.96) and grade of cataract (p = 0.177). Group C was associated with significant reductions in CDE (p = 0.001), EFU (p < 0.0005) as well as TAT (p = 0.001) in comparison to the other groups. All three groups had comparable baseline endothelial cell density (p = 0.876) and central corneal thickness (p = 0.561). On post-operative evaluation, although all groups were comparable till 3 months, by 6 months, the percentage losses in endothelial cell density were significantly lower in group C as compared to the other groups.

Conclusions

Use of an IOP based phacoemulsification system in association with use of the Intrepid balanced tip reduces the CDE, EFU and TAT in comparison to a gravity fed system with a mini flared tip or IOP based system with a mini flared tip while also providing better endothelial preservation thus favouring the use of an IOP fed system with a balanced tip.

Trial registration

Trial registration No.: CTRI/2016/06/007022.