Safety Profile of Venturi Versus Peristaltic Phacoemulsification Pumps in Cataract Surgery Using a Capsular Surrogate for the Human Lens

Efficiency of a polymer-coated phacoemulsification tip in cataract surgery

PURPOSE

To determine whether there is a difference in efficiency during phacoemulsification when using the hybrid polymer tip compared with the metal balanced tip, as measured by cumulative dissipated energy (CDE) and total procedure time.

SETTING

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

DESIGN

Experimental study.

METHODS

Phacoemulsification was performed with the Centurion Vision System and Infiniti OZil handpiece, with a 30-degree bevel metal balanced tip and hybrid polymer tip. The vacuum was set at 500 mm Hg and the aspiration flow rate at 50 mL/min. Power was changed for torsional and longitudinal ultrasound (US) at 20%, 40%, 60%, 80%, and 100%. Hardened porcine lenses were cut into 200 two mm cubes, 10 for each specified tip/power setting. They were placed into an artificial anterior chamber filled with a balanced salt solution, and phacoemulsification was performed. A second observer randomly assigned the US type and power. The same observer timed trials with a stopwatch, and CDE was recorded.

RESULTS

There were no significant differences in time or CDE for any power levels or US modes when comparing the 2 tips.

CONCLUSIONS

No significant difference in efficiency was observed when comparing the metal balanced tip with the hybrid polymer tip. Given the known improved safety profile and the overall equivalent efficiency of the hybrid tip, it could improve the performance of beginning and advanced surgeons in the future. Future study is needed to evaluate other setting combinations and to evaluate the hybrid tip in clinical settings.

Effect of Modified Peristaltic Phacoemulsification Device on Efficiency and Post-Occlusion Pressure Surge

Purpose

To evaluate efficiency of grooving, nuclear fragment removal, and changes in pressure control in the Oertli Faros using traditional peristaltic and Speed and Precision (SPEEP) features. The SPEEP mode uses novel peristaltic technology permitting independent control of flow and vacuum.

Methods

A porcine lens model was used with an enclosed chamber simulating the anterior segment. Grooving efficiency is evaluated with flow rates of 10, 30, and 50 mL/min using whole lenses. Lens cubes were emulsified at 20, 40, 60, 80, and 100% power with both SPEEP and non-SPEEP modes. Surge was evaluated with pressure gauges placed on the irrigation tubing and aspiration tubing. Pressure readings were recorded per the following: fluid and vacuum were initiated for 15 seconds, vacuum tubing was occluded for 5 seconds, tubing patency was then re-introduced for 15 seconds. Differences between sensors were recorded.

Results

No significant increase in efficiency was seen with increasing flow rate from 30 to 50 mL/min using SPEEP. No significant differences were shown in lens fragment removal in SPEEP and non-SPEEP modes at any power tested. Pressure difference measurements were not significantly different with SPEEP and non-SPEEP modes.

Conclusion

We showed that lower flow rates show comparable efficiency of grooving when using the SPEEP mode. The SPEEP function did not show increased efficiency in nuclear fragment removal when compared to traditional mode. Surge control was also comparable with both SPEEP and non-SPEEP modes. We suggest that the SPEEP function included in the Oertli Faros may have some advantages.

Preferred cataract surgery practices in Malaysia: a survey based study

BACKGROUND

To describe the preferred cataract surgery practices among Malaysian ophthalmologists and medical officers in comparison with the recommended practices.

METHODS

An online questionnaire was sent out in April 2021, to Malaysian Ophthalmologists and medical officers who perform cataract surgeries. The questions were focused on the preferred cataract surgery practices of the participants. All data obtained were collected, tabulated and analysed.

RESULTS

A total of 173 participants responded to the online questionnaire. 55% of the participants were within 31-40 years of age. 56.1% preferred peristaltic pump over venturi system. 91.3% of participants practised povidone iodine instillation to the conjunctival sac. With regards to the main wound incision, more than half of the surgeons (50.3%) preferred fixed superior incision and 72.3% of them preferred 2.75 mm microkeratome blade. Most of the participants (63%) were inclined towards C-Loop clear intraocular lens (IOL) with a single-handed push preloaded system. 78.6% of the surgeons routinely use carbachol in their cataract surgery.

CONCLUSIONS

This survey provides some insight into the current practices among Malaysian ophthalmologists. Most of the practices are in line with international guidelines for preventing postoperative endophthalmitis. This article could help trainees and ophthalmologists benchmark and observe the common cataract surgery practices among their seniors and peers in Malaysia.

Optimizing Tip Diameter in Phacoemulsification of Varying Lens Sizes: An in vitro Study

Purpose

We assessed the effect of two lens cube sizes, three tip sizes, and two ultrasound (US) approaches on phacoemulsification efficiency and chatter.

Methods

After porcine lens nuclei were soaked in formalin, we divided them into cubes measuring 2.0 mm or 3.0 mm. We collected efficiency and chatter data for 30-degree bent 19 G, 20 G, and 21 G tips with a continuous torsional US system; and for straight 19 G, 20 G, and 21 G tips with a micropulse longitudinal US system.

Results

The average time needed for removal was always higher for the 3.0 mm lens cube than for the 2.0 mm lens cube. Statistically significant differences were observed between the 19 G and 21 G tips with micropulse longitudinal US using a 2.0 mm cube and a 3.0 mm cube, and with continuous transversal US using a 2.0 mm lens cube and a 3.0 mm cube. We did not observe significant differences between 19 G and 20 G tips with either cube size in either US system. However, we noted identical trends for both cube sizes with both US approaches; 19 G tips performed better than 20 G and 21 G tips.

Conclusion

Regardless of the lens size, 19 G needles were the most efficient, and had both the fewest outliers and the smallest standard deviations.

The effect of increasing power when grooving using phacoemulsification

PURPOSE

To determine optimal power settings on the Centurion Vision System during the grooving step in cataract surgery.

METHODS

Intact porcine lenses hardened by formalin and placed in a chamber designed to simulate the anterior chamber of the eye were used to test longitudinal power at 40%, 70%, and 100% and torsional power at 0%. Flow rate was set at 40 mL/min. Vacuum was set at 400 mmHg, intraocular pressure was set at 50 mmHg, and a balanced phacoemulsification tip with a 20 degree tip and a 30 degree bevel was used. Efficiency (time to groove the lens in half) was determined.

RESULTS

Increasing longitudinal power from 40% to 70% increased efficiency by 28% (P<0.05), and by 32% (P<0.05) when increasing longitudinal power from 40% to 100%. There was no statistically significant increase in efficiency from 70% to 100%.

CONCLUSION

For the tested variables, a longitudinal power of 70% was determined to be most efficient during the grooving step of cataract surgery for equivalent 3-4+ nuclei. Further increases in power demonstrated no statistically significant improvement in efficiency.

Effect of increasing flow when grooving during phacoemulsification

PURPOSE

To determine optimum flow settings on the Centurion Vision System during the grooving step in cataract surgery.

SETTING

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

DESIGN

Experimental study.

METHODS

Intact porcine lenses hardened by formalin and placed in a chamber designed to simulate the anterior chamber of the eye were used to test flow rate settings at 20 mL/min, 40 mL/min, and 60 mL/min. Vacuum was set at 400 mm Hg, longitudinal power at 80%, torsional power at 80%, and intraocular pressure at 50 mm Hg. A balanced phaco tip with a 20-degree tip and a 30-degree bevel was used. Efficiency (time to groove the lens in half) was determined.

RESULTS

Increasing flow from 20 to 40 mL/min during grooving increased efficiency by 17% (P = .05), with no significant improvement shown at 60 mL/min.

CONCLUSIONS

A flow rate of 40 mL/min was determined to be most efficient during the grooving step of cataract surgery. Further increases in flow rate showed no statistically significant improvement in efficiency, and with only 17% improvement flow rates less than 40 mL/min might be almost as efficient and might be safer.