Thermal imaging study comparing phacoemulsification with the Sovereign with WhiteStar system to the Legacy with AdvanTec and NeoSoniX system

Eyelid and scleral thermal injury following phacoemulsification in silicone oil: a case report

Background

Phacoemulsification has been the mainstay method for extracapsular cataract extraction surgery in the anterior segment; for cases of posterior drop of lens fragments into the vitreous, a posterior segment phacoemulsification instrument (fragmatome; Alcon, Inc., Fort Worth, TX) can be employed to remove the dislocated lens materials. Studies have reported on thermal injury to the cornea during phacmoemulsification of the anterior segment. However, few studies have investigated thermal burn in the simultaneous sclera and eyelid induced by the fragmatome. Currently, there is no reports and lack of optimal strategy for the management of nucleus drop in a vitreous cavity filled with silicon oil.

Case Presentation

We present the case of a 53-year-old male patient with a thermal burn wound on the upper eyelid and sclera following phacoemulsification for a dropped lens in a silicone oil-filled vitreous. We further designed an experiment to verify our hypothesis that thermal injury could be induced by the high temperature of the metal tip during phacoemulsification in silicone oil. In our experiment, during 420 s of continuous ultrasonic wave, the temperature of the fragmatome tip in the balanced salt solution (BSS) increased from 22.0 to 24.0 ºC, while the temperature of the fragmatome tip in the silicone oil group increased from 22.0 to 43.0 ºC.

Conclusions

The temperature of the fragmatome tip increased significantly in silicone oil compared to BSS in the experiment. Thus, physicians should be aware of possible thermal complications when using fragmatome in eyes filled with silicone oil.

Transient temperature distribution on the corneal endothelium during ophthalmic phacoemulsification: a numerical simulation using the nodeless variable element

Background: During cataract operation (phacoemulsification), a phaco needle-tip is inserted into the anterior chamber of eye. Then, heat is generated by the oscillation of the phaco needle, which may injury the corneal endothelial cells. There are no data available for temperature responses at the corneal endothelium to heat from the phaco needle during phacoemulsification. Objective: Investigate temperature distribution on the corneal endothelium during ophthalmic phacoemulsification using numerical simulation, and compare the transient temperature response to heat between balanced salt solution (BSS) and ophthalmic viscoelastic device (OVD), Viscoat®. Methods: Heat flux from a phaco needle was measured with thermal properties of BSS and AVS in an experimental setting. Then, nodeless variable finite element method was applied to predict temperature changes in the eye by the phaco needle inserted into the anterior chamber. The transient temperature distribution on the corneal endothelium was calculated at 10, 20, and 30 seconds after heat generation by the needle. Results: The heat generation of phaco needle without sleeve cover was 1.6 kW/m2. The numerical simulation showed that the maximum temperature occurs on the wound location at all times after heat generation by the phaco needle. Especially, at time 30 seconds, it was 49.2 and 41.7°C in BSS and OVD, respectively. The temperature elevation by the phaco needle was lower in OVD than BSS. Conclusion: Phacoemulsification is a heat-generating procedure performed between the anterior chamber structures of eye. During this procedure, OVD may protect the corneal endothelium against heat better than BSS.

Wound and surface temperatures in vivo in torsional and longitudinal modalities of ultrasound in coaxial microincisional cataract surgery

BACKGROUND

To study phacoemulsification probe shaft/wound and corneal surface/tip temperatures in vivo during longitudinal, torsional and combined phacoemulsification modes and their relationship to machine parameters.

DESIGN

This was a prospective study at Chaithanya Eye Hospital and Research Institute, Trivandrum, India (tertiary).

PARTICIPANTS

Twenty-two eyes of 22 patients were randomized into six groups depending on the grade of nuclear sclerosis (NS) and the type of ultrasound used: Group 1, torsional in NS2; Group 2, torsional in NS3; Group 3, torsional with intermittent longitudinal in NS2; Group 4, torsional with intermittent longitudinal in NS3; Group 5, longitudinal in NS2; Group 6, longitudinal in NS3.

METHODS

Patients underwent phacoemulsification by torsional, longitudinal or combined modalities. A thermal camera was used to measure phaco probe temperatures.

MAIN OUTCOME MEASURES

The mean probe shaft and tip temperatures were documented for different ultrasound modalities.

RESULTS

The mean shaft and tip temperatures were: Group 1, 29.22°C±0.71°C and 28.4°C±0.88°C; Group 2, 32.12°C±0.62°C and 31.88°C±0.84°C; Group 3, 30.25°C±0.71°C and 29.35°C±0.62°C; Group 4, 31.95°C±0.65°C and 32.01°C±1.31°C; Group 5, 23°C and 27.6°C and Group 6, 23°C and 29.68°C, respectively. In all groups using longitudinal ultrasound, the phaco tip surface temperatures were higher than the shaft temperatures, except in Group 3. Shaft temperatures were higher than tip temperatures in cases using torsional phaco, except in Group 4. The mean temperature difference between groups was significant only for shaft temperatures (P=0.001). On thermal imaging, for torsional phaco, the rise in temperature of the probe from shaft to tip was dependent on the amplitude of ultrasound applied (P=0.009).

CONCLUSION

The shaft temperatures were higher than over the phaco tip during torsional phacoemulsification.

Torsional mode phacoemulsification: effective, safe cataract surgery technique of the future

Purpose:

To compare various outcome measures using torsional mode and longitudinal mode in the phacoemulsification of cataract with different nuclear densities.

Setting:

Magrabi Eye Hospitals, Kingdom of Saudi Arabia.

Design:

A randomized comparative clinical study.

Materials and Methods:

This study includes 200 eyes of 156 patients (100 in the ultrasound longitudinal “US” group and 100 in the torsional group). All eyes received AcrySof^® single piece intraocular lens (Alcon Surgical, Fort Worth, TX). The primary outcome measures were ultrasound time (UST), cumulative dissipated energy (CDE), and surgical complications. Postoperative outcome measures were the degree of corneal edema on the first postoperative day and final best corrected visual acuity (BCVA) and CCT (central corneal thickness).

Results:

The differences in UST and CDE between subgroups of nucleus hardness were statistically significant (P < 0.01). The UST and CDE consistently increased in eyes with higher grades of nucleus density. On day one, the mean BCVA was 0.61 ± 0.13 decimals in the ultrasound (US) group and 0.67 ± 0.11 decimals in the torsional group (significant P < 0.05). Corneal edema was significantly less in the torsional group (P < 0.05). At 30 days, the mean BCVA was 0.94 ± 0.22 decimals in the US group and 1.0 ± 0.12 decimals in the torsional group but this difference was not statistically different (P > 0.05).

Conclusions:

The torsional mode provides an effective and safe method for cataract removal with lower energy usage as compared to longitudinal traditional phacoemulsification. However, the final visual outcome was similar for both study groups.

Infrared thermography as an access pathway for individuals with severe motor impairments

BACKGROUND

People with severe motor impairments often require an alternative access pathway, such as a binary switch, to communicate and to interact with their environment. A wide range of access pathways have been developed from simple mechanical switches to sophisticated physiological ones. In this manuscript we report the inaugural investigation of infrared thermography as a non-invasive and non-contact access pathway by which individuals with disabilities can interact and perhaps eventually communicate.

METHODS

Our method exploits the local temperature changes associated with mouth opening/closing to enable a highly sensitive and specific binary switch. Ten participants (two with severe disabilities) provided examples of mouth opening and closing. Thermographic videos of each participant were recorded with an infrared thermal camera and processed using a computerized algorithm. The algorithm detected a mouth open-close pattern using a combination of adaptive thermal intensity filtering, motion tracking and morphological analysis.

RESULTS

High detection sensitivity and low error rate were achieved for the majority of the participants (mean sensitivity of all participants: 88.5% +/- 11.3; mean specificity of all participants: 99.4% +/- 0.7). The algorithm performance was robust against participant motion and changes in the background scene.

CONCLUSION

Our findings suggest that further research on the infrared thermographic access pathway is warranted. Flexible camera location, convenience of use and robustness to ambient lighting levels, changes in background scene and extraneous body movements make this a potential new access modality that can be used night or day in unconstrained environments.

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.

Innovations in phacoemulsification technology

PURPOSE OF REVIEW

A working knowledge of the principles guiding recent technologic upgrades in phacoemulsification units will help the surgeon to maximize clinical benefits from the latest machines.

RECENT FINDINGS

Reduced thermal energy combined with more efficient emulsification resulting from microfractionation of ultrasound energy, and improved chamber stability from automatic fluidic adjustments are achievable with the recent technological advances.

SUMMARY

Improved safety and efficiency can be achieved with the most current advances in phacoemulsification technology.