Feasibility of sleeveless bimanual phacoemulsification with the Millennium microsurgical system

Thermal study of longitudinal and torsional ultrasound phacoemulsification: tracking the temperature of the corneal surface, incision, and handpiece

PURPOSE

To evaluate the change and difference in the corneal surface, incision, and handpiece temperatures during longitudinal and torsional ultrasound (US) phacoemulsification with standard incisions (2.75 mm) and microincisions (2.20 mm) and the thermal effect on wounds.

SETTING

Department of Ophthalmology, Duke University, Durham, North Carolina, USA.

METHODS

In this prospective study, human cadaver eyes had simulated phacoemulsification. Group 1 had a 2.75 mm incision with 100% longitudinal US; Group 2, a 2.20 mm incision with 100% longitudinal US; Group 3, a 2.75 mm incision with 100% torsional US; and Group 4, a 2.20 mm incision with 100% torsional US. During phacoemulsification, the corneal incision was evaluated by surgical microscopy and scanning electron microscopy (SEM) and images of the corneal surface, incision, and handpiece were captured with an infrared camera.

RESULTS

Twelve eyes (3 each group) were evaluated. The maximum incision temperature was higher in the longitudinal groups than in the torsional groups. With the same US modality, the maximum microincision temperature was higher than the maximum standard incision temperature. After application of full power for 40 seconds, wound burn was observed in all eyes in the longitudinal groups and no eyes in the torsional groups. On SEM, there was more extensive loss of Descemet membrane in the longitudinal groups than in the torsional groups.

CONCLUSION

Incision temperature was influenced by US modality and was significantly lower with torsional US than with longitudinal US. Using torsional US with smaller incisions may decrease the risk for wound burn in eyes with denser cataracts.

Intraocular pressure changes during injection of microincision and conventional intraocular lenses through incisions smaller than 3.0 mm

PURPOSE

To compare intraocular pressure (IOP) during insertion of a new microincision intraocular lens (IOL) (Akreos AO MI60) and a conventional IOL (AcrySof Natural SN60AT) and to determine the minimum incision sizes for insertion in a cadaver eye model.

SETTING

John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA.

METHODS

After phacoemulsification in phakic cadaver eyes, multiple IOL insertions were attempted through 1.8 mm to 2.5 mm wounds. The final incision size and insertion success were evaluated in each case. A pressure transducer placed in the vitreous cavity measured real-time IOP changes (100 readings per second), including the mean and peak IOP during IOL implantation.

RESULTS

The minimum incision size for the microincision IOL insertion was 1.9 mm using a wound-assisted technique and 2.2 mm using a cartridge-insertion technique. The minimum incision size for wound-assisted implantation of the conventional IOL was 2.4 mm. During successful implantation, the mean and peak IOPs were similar between the 2 IOL types. The peak IOPs exceeded 60 mm Hg (retinal perfusion pressure). In unsuccessful attempts, the mean and peak IOPs were higher for the conventional IOL, reaching 306.05 mm Hg in 1 eye.

CONCLUSIONS

Monitoring during implantation of both IOL types confirmed that IOP increases during insertion, including during microincision surgery using a wound-assisted technique. Further studies are necessary to evaluate the effect of pressure spikes on the optic nerve during IOL insertion.

Determining Factors for Corneal Endothelial Cell Loss by Using Bimanual Microincision Phacoemulsification and Power Modulation

PURPOSE

To determine risk factors for central corneal endothelial cell loss in bimanual microincision cataract surgery by using power modulation.

METHODS

Prospective study: 79 eyes (70 subjects) with uncomplicated bimanual cataract surgery by using power modulation. Cataracts were graded with the LOCS III system. Specular microscopy was performed preoperatively and postoperatively (5 weeks). Endothelial cell density was calculated (CD; cells/square millimeter). Endothelial cell loss (ECL = preoperative CD - postoperative CD; cells/square millimeter) and proportional loss of cells [PLC = (ECL/preoperative CD) x 100; %)] were calculated. Phacoemulsification time (seconds) and average phacoemulsification power in foot position 3 (%) were recorded.

RESULTS

Cataracts were moderate to high density, nuclear color = 3.96, and nuclear opalescence = 3.91. Endothelial cell loss = 196 cells/square millimeter (P < 0.0001). Proportional loss of cells = 8.12% (P < 0.0001). Average phacoemulsification power in foot position 3 was low (8.17%). Increased nuclear color and opalescence were correlated with more phacoemulsification time and higher average phacoemulsification power in foot position 3 (P < 0.0001). Endothelial cell loss and proportional loss of cells, respectively, were affected by increased nuclear color (P < 0.004, P < 0.003) and opalescence (P < 0.006, P < 0.004) but were not affected by phacoemulsification time. Average phacoemulsification power in foot position 3 had a mild effect on endothelial cell loss and proportional loss of cells (P = 0.02, P = 0.02).

CONCLUSIONS

Despite the need for longer phacoemulsification time and increased power to emulsify denser cataracts, the amount of endothelial cell loss was only mildly affected by the average phacoemulsification power in foot position 3 and unaffected by total phacoemulsification time, showing that bimanual phacoemulsification with power modulation is an efficient and effective technique for performing cataract surgery.

Intraoperative performance and postoperative outcomes of microcoaxial phacoemulsification

PURPOSE

To evaluate the intraoperative performance and postoperative outcomes after microcoaxial phacoemulsification.

SETTING

Iladevi Cataract & IOL Research Centre, Ahmedabad, India.

METHODS

A prospective observational case series comprised 84 eyes with age-related uncomplicated cataract having microcoaxial phacoemulsification through a 2.2 mm clear corneal incision by a standard surgical technique. Phacoemulsification parameters (Infiniti Vision System, Alcon) were microburst width, 30 ms; preset power, 50%; vacuum, 650 mm Hg; aspiration flow rate, 25 cc/minute. A single-piece Alcon AcrySof intraocular lens was implanted with the C cartridge (Alcon) cartridge. The incision was measured at the end of surgery. Observations included surgical time (from commencement of sculpting to end of epinucleus removal), cumulative dissipated energy (CDE), wound burns, intraoperative complications, postoperative increase in mean central corneal thickness (CCT) at 1 day and 1 month, mean % decrease in endothelial cell density (ECD), absolute mean change in coefficient of variation (cv) 3 months, and uncorrected visual acuity (UCVA) at 1 day. Data were analyzed using a 1-sample t test with 95% confidence intervals (CIs).

RESULTS

The mean follow up was 3 months +/- 0.3 (SD). The mean incision size at the end of surgery was 2.3 +/- .09 mm; mean surgical time, 4.5 +/- 1.5 minutes; and mean CDE, 2.3 +/- 2.2 seconds. No wound burns or other intraoperative complications occurred. The postoperative CCT increased by a mean of 16 microm at 1 day (95% CI, 8-25; P = .66;) and by a mean of 3.14 microm at 1 month (95% CI, 2.26-4.05; P = .92). The ECD decreased by a mean of 5.8% (95% CI, 6.8-3.5; P = .82) and the mean coefficient of variation, by 3.3 (95% CI, 4.5-2.0; P = .65). At 1 day, the UCVA was 20/20 in 29% of cases, 20/20 to 20/40 in 58%, and 20/40 to 20/50 in 12%.

CONCLUSION

Microcoaxial phacoemulsification was safely and effectively performed, achieving consistent and satisfactory postoperative outcomes.

Corneal wound architecture and integrity after phacoemulsification

PURPOSE

To compare the effects of microincision bimanual phacoemulsification, standard coaxial phacoemulsification, and microincision coaxial phacoemulsification on clear corneal incision architecture and wound integrity.

SETTING

Department of Ophthalmology, Duke University, Durham, North Carolina, USA.

METHODS

A prospective study of 15 human cadaver eyes (3 groups of 5 eyes) ranging 1 to 4 days postmortem had simulated phacoemulsification by bimanual phacoemulsification (1.2 mm incision), standard coaxial phacoemulsification (2.75 mm), or microincision coaxial phacoemulsification (2.2 mm). All phacoemulsification settings were kept constant across each group. After phacoemulsification, intraocular pressure (IOP) was cyclically raised and lowered from 0 to 125 mm Hg. Two eyes in each group had India ink placed above the wound, and the IOP was varied as above. Entry of India ink into the wound or aqueous leakage from the wound was recorded. The same 2 corneas in each group were removed for histopathologic review of India ink penetration. Scanning electron microscopy was used to evaluate wound architecture in 1 eye in each group.

RESULTS

Spontaneous wound leakage was evident in all 5 eyes having bimanual phacoemulsification, in 1 eye (20%) having standard coaxial phacoemulsification, and no eye having microincision coaxial phacoemulsification. India ink penetration was grossly evident in 2 of 2 eyes having bimanual phacoemulsification, 1 of 2 eyes having standard coaxial phacoemulsification, and neither of the 2 eyes having microincision coaxial phacoemulsification. Scanning electron microscopy showed increased endothelial cell loss and greater compromise to Descemet's membrane with bimanual phacoemulsification than with standard coaxial phacoemulsification or microincision coaxial phacoemulsification.

CONCLUSION

Results in this experimental setting suggest microincision coaxial phacoemulsification and standard coaxial phacoemulsification induce less wound stress and alteration of wound morphology leading to wound leakage than microincision bimanual phacoemulsification.

Safety and Efficacy of Micro-Incisional Cataract Surgery with Bimanual Phacoemulsification for White Mature Cataract

BACKGROUND

To evaluate the safety and efficacy of micro-incisional cataract surgery (MICS) with bimanual phacoemulsification for the management of white mature cataract.

METHODS

Twenty-five eyes in 25 patients with mature cataract were prospectively recruited to undergo MICS with bimanual phacoemulsification. Serial changes in best-corrected visual acuity (BCVA), central corneal thickness (CCT) and endothelial cell density (ECD) were compared using the Wilcoxon signed-rank test.

RESULTS

MICS was successfully performed in 24 (96%) of the 25 eyes, with 1 eye requiring conversion to extracapsular cataract extraction due to radial tear during continuous curvilinear capsulorhexis. The median preoperative BCVA was hand movement. On day 1 postoperatively, the median BCVA improved to 0.6 (p < 0.001 compared with baseline). All patients had BCVA of 0.6 or better at 3 months after surgery (p < 0.001 compared with baseline). The mean increase in CCT at day 1 and week 1 postoperatively was 11.5 and 7.1%, respectively. The change in mean CCT was no longer significant at month 3 postoperatively (p = 0.82). The mean reduction in ECD at 3 months postoperatively was 7.8% (p = 0.037). None of the patients developed any postoperative complications.

CONCLUSIONS

MICS with bimanual phacoemulsification appeared to be a promising alterative for the management of white mature cataract.

Clinical evaluation using Custom Control Software technology in coaxial phacoemulsification

PURPOSE

The aim of this study was to evaluate the clinical outcomes of the Custom Control Software technology in coaxial phacoemulsification.

METHODS

This prospective, randomized, double-masked clinical trial was conducted at the Eye Center, Affiliated Second Hospital, College of Medicine, Zhejiang University. The patients were grouped according to nuclear sclerosis and randomly assigned to undergo conventional phacoemulsification or phacoemulsification using Millennium Custom Control Software (CCS). All surgeries were performed by a single surgeon. The phaco time and average power of phacoemulsification were recorded and then calculated as absolute phaco time (APT). Visual acuity, pachymetry, endothelial cell density and anterior chamber flare count of both groups were noted at preoperatively day 1 and 3 months after surgery.

RESULTS

The APT of the CCS group was statistically lower than Conventional group in grades II, III and IV (P < 0.05) nuclear sclerosis, but the two groups had no statistically significant differences in the grade I group. At day 1 post surgery, there were significant differences in the thickened pachymetry (P = 0.047) and anterior chamber flare counts (P = 0.008) between two groups. At 3 months post surgery, the endothelial cell loss ratio showed statistical difference (P = 0.032) between two groups.

CONCLUSIONS

Using CCS technology in coaxial phacoemulsification can provide lower APT and better power efficiency. This new power modulation may make the surgery safer and more effective than Conventional phacoemulsification.

Microincision bimanual phacotrabeculectomy in eyes with coexisting glaucoma and cataract

PURPOSE

To report the technique and surgical outcomes of microincision bimanual phacotrabeculectomy in eyes with glaucoma and coexisting cataract.

SETTING

Glaucoma Service, Hong Kong Eye Hospital, Hong Kong SAR, China

METHODS

Microincision bimanual phacoemulsification with a sleeveless phaco needle and irrigating chopper was performed in combination with trabeculectomy. Phacoemulsification was performed through 2 small clear corneal wounds, sparing the trabeculectomy site from trauma. The intraocular lens (IOL) was then implanted through the trabeculectomy site, so no corneal wound larger than 1.5 mm was required for IOL implantation.

RESULTS

The first 10 consecutive eyes of 10 patients who had combined phacotrabeculectomy by a microincision bimanual technique had significantly reduced intraocular pressure. There was a 10.5% reduction in the mean corneal endothelial cell count. There were no other complications up to 6 months after surgery.

CONCLUSION

Microincision bimanual phacotrabeculectomy appeared to be an effective and safe option in patients with glaucoma and coexisting cataract.

Thermal effect of microburst and hyperpulse settings during sleeveless bimanual phacoemulsification with advanced power modulations

PURPOSE

To assess wound temperature during bimanual sleeveless phacoemulsification using customizable power modulations such as hyperpulse and microburst technology.

SETTING

In vitro laboratory.

METHODS

The Millennium Microsurgical System (Bausch & Lomb) with custom control software (CCS) was used to perform phacoemulsification in 5 porcine eyes with MicroFlow needles (Bausch & Lomb) and with power varied from 20% to 80% in 10% increments. Pulse modes were set for fixed microburst (4 ms on, 4 ms off; and 6 ms on, 12 or 24 ms off) and for hyperpulse (30% duty cycle with 8 or 75 pulses per second [pps]), with and without aspiration-line occlusion. Wound temperatures were measured 3 times per second.

RESULTS

Using 80% total power, the wound temperature during 3 minutes of occlusion did not exceed 39.0 degrees C. The maximum temperature with fixed microbursts of 4 ms on, 4 ms off was 29.0 degrees C without occlusion and 37.8 degrees C with occlusion (duration 3 minutes). At 6 ms on, 12 ms off, the maximum temperatures were 28.1 degrees C and 38.7 degrees C, respectively. At 6 ms on, 24 ms off, peak temperatures were 24 degrees C and 23.6 degrees C, respectively. The hyperpulse mode of 30% duty cycle and 8 pps produced maximum temperatures of 25.5 degrees C nonoccluded and 33.4 degrees C occluded. With 30% duty cycle, 75 pps, temperatures were 28 degrees C and 38.0 degrees C, respectively. For all power below 80%, temperatures were lower.

CONCLUSIONS

Customizable power modulation with microburst and hyperpulse technology further reduced wound temperatures during bimanual sleeveless phacoemulsification. This enhances the safety and effectiveness of phacoemulsification through a sleeveless needle and a small stab incision.

Update on bimanual microincisional cataract surgery

PURPOSE OF REVIEW

This review examines the current status of accommodation restoration concepts with reference to the recent, published peer-reviewed literature with an emphasis on physiological aspects of accommodation and presbyopia.

RECENT FINDINGS

The mechanisms of accommodation and the causes of presbyopia are described. The physiological amenability of the accommodative structures in the presbyopic eye to accommodation restoration is discussed. General theoretical concepts of accommodation restoration are introduced. The methods that have been used to assess accommodation restoration, including the use of animal models, drug stimulated accommodation, subjective near-vision tests and objective measurements, are reviewed.

SUMMARY

While physiological and clinical evidence supports the notion that accommodation can be restored to the presbyopic eye, progress in this potentially exciting area is hindered by the scarcity of good, large-scale clinical studies using objective measurement techniques to evaluate the outcomes of accommodation restoration concepts.

Quantitative thermographic analysis of viscoelastic substances in an experimental study in rabbits

PURPOSE

To measure the temperature parameters on the corneal surface during the delivery of standardized ultrasound energy assisted with ophthalmic viscosurgical devices (OVDs) or different temperatures of irrigating solutions in an experimental animal model.

SETTING

Department of Ophthalmology and Visual Rehabilitation, Medical University of Lodz, and Central Institute for Labor Protection, National Research Institute, Warsaw, Poland.

METHODS

Thirty rabbits (60 eyes) were randomly divided into 6 groups in which different OVD or balanced salt solutions (BSS) were used: group 1: Viscoat (sodium hyaluronate 3%-chondroitin sulfate); group 2: Provisc (sodium hyaluronate 1%); group 3: soft-shell technique; group 4: Celoftal (hydroxypropyl methylcellulose 2%); group 5: BSS 22 degrees C; and group 6: BSS 4 degrees C. After the nucleus and lens cortex were removed, the anterior chamber was filled with OVD or BSS and a phaco tip was introduced into the pupillary plane and switched on. The same phaco tip parameters were used in all groups. For thermographic measurements (ie, maximal temperature [MT], dynamic rise in temperature [DRT], and time when the maximal level of temperature [TMLT] was achieved), a thermocamera was used.

RESULTS

Mean preoperative temperature on the rabbit corneal surface was 22.76 degrees C +/- 1.48 degrees C (SD). Working with a phaco tip increased the temperature in each group. A significantly higher MT was observed in group 5 (27.85 degrees C +/- 0.52 degrees C), followed by group 2 (27.75 degrees C +/- 0.54 degrees C), group 3 (27.74 degrees C +/- 0.46 degrees C), and group 4 (27.25 degrees C +/- 0.60 degrees C), than in group 6 (26.81 degrees C +/- 0.34 degrees C) and group 1 (26.52 degrees C +/- 0.48 degrees C) (P<.05). Significantly higher values of DRT and shorter TMLT values were observed in group 5 (1.16 degrees C/s +/- 0.42 degrees C/s, 4 seconds) and group 6 (0.91 degrees C/s +/- 0.13 degrees C/s, 5 seconds) than in groups 2, 3, 1, and 4 (0.09 degrees C/s +/- 0.07 degrees C/s, 30 seconds; 0.08 degrees C/s +/- 0.04 degrees C/s, 40 seconds; 0.07 degrees C/s +/- 0.03 degrees C/s, 45 seconds; 0.06 degrees C/s +/- 0.02 degrees C/s, 50 seconds, respectively) (P<.0001).

CONCLUSIONS

Currently used OVDs potentially offer different levels of protection against the increase in temperature that occurs during phacoemulsification. Therefore, the surgeon should consider this aspect when choosing an OVD, particularly in difficult cases (ie, hard nucleus, shallow anterior chamber, endothelial abnormalities).

Outcomes of Microincision Cataract Surgery versus Coaxial Phacoemulsification

PURPOSE

To compare outcomes of microincision cataract surgery (MICS) with coaxial phacoemulsification.

DESIGN

Prospective randomized consecutive case series.

PARTICIPANTS

One hundred eyes of 50 patients with nuclear or corticonuclear cataract (grades 2+ to 4) with Lens Opacities Classification System III.

METHODS

One hundred eyes (50 patients) were randomly operated through clear corneal incisions using 2 techniques: coaxial phacoemulsification (50 eyes) and microincision cataract surgery (50 eyes).

MAIN OUTCOME MEASURES

Mean phacoemulsification time, total phacoemulsification percent, effective phacoemulsification time (EPT) (calculated by multiplying total phacoemulsification time in seconds by the average power percent used), intraoperative total balanced salt solution (BSS) volume, visual outcome, vectorial astigmatic changes, corneal thickness, endothelial cell count, and anterior chamber flare and cells preoperatively and at 1 day, 1 month, and 3 months.

RESULTS

Statistically significant differences were found between MICS and coaxial phacoemulsification regarding mean incision size, mean total phacoemulsification percent, and EPT. There were no significant differences between the techniques regarding the mean percent of endothelial cell loss, anterior chamber cell count and flare, mean phacoemulsification time, pachymetric measures or total BSS volume utilized, or visual outcome. The vectorial astigmatic changes in the MICS group showed a change of < or =0.25 diopters (D) in 35% of the eyes, 0.25 to 0.5 D in 50% of the eyes, and 0.5 to 1.0 D in 15% of the eyes. These changes were induced by the surgery. Vectorial astigmatic changes of >1 D were not observed. In the coaxial phacoemulsification group, vectorial astigmatic changes of <0.25 D were not observed either. Changes of 0.25 to 0.5 D were seen in 20% of the eyes, and changes of 0.5 to 1.0 D were seen in 30%. Fifty percent of the eyes showed changes of >1.0 D. Mean vectorial astigmatic changes were 0.36+/-0.23 D in the MICS group and 1.2+/-0.74 D in the coaxial phacoemulsification group (P<0.001).

CONCLUSIONS

Microincision cataract surgery significantly lowered mean phacoemulsification time, mean total phacoemulsification percent, mean EPT, and surgically induced astigmatism when compared with coaxial phacoemulsification.

New phacoemulsification technology

PURPOSE OF REVIEW

Familiarization with each of the manufacturers' latest machines and upgrades assists in understanding the advances made in phacoemulsification technology.

RECENT FINDINGS

Improvements in the delivery of energy through power modulations, alternative and adjunctive energy sources, and advanced fluidics allow the safe use of bimanual microincision techniques for lens extraction.

SUMMARY

Continual advances in phacoemulsification technology and adjunctive surgical devices allow cataract surgery to be performed more safely and efficiently.

Bimanual microincisional phacoemulsification: the future of cataract surgery?

PURPOSE OF REVIEW

Bimanual microincisional cataract surgery has recently become a procedure of interest among cataract surgeons, and a number of trials have shown its potential as a minimally invasive cataract surgery. The purpose of this review is to examine the studies that have been published to date and to evaluate the potential of bimanual phacoemulsification as a method of cataract extraction.

RECENT FINDINGS

Recent studies have reinforced the safety of bimanual phacoemulsification. In particular, recently published studies have focused on evaluating various phacoemulsification technologies and their safety when used in bimanual phacoemulsification. Newly developed rollable hydrophilic acrylic ThinOptX lenses have been shown to be implantable in 2.2-mm incisions safely with good visual outcomes.

SUMMARY

Bimanual phacoemulsification has been a potential technique for a number of years, but only recently have the technology, software, and technique advanced sufficiently to make bimanual phacoemulsification a feasible method of cataract extraction. Although the main disadvantage to bimanual phacoemulsification remains the lack of intraocular lenses that can fit through microincisions, necessitating the enlargement of corneal wounds for intraocular lens implantation, bimanual phacoemulsification has a number of advantages over traditional small-incision phacoemulsification. Theses advantages have been a source of interest for cataract surgeons and surgical companies who are now developing technologies that will permit the performance of truly microincisional cataract surgery.