Effect of chamber stabilization software on efficiency and chatter in a porcine lens model

Optimization of Phacoemulsification Tip Gauge on the Oertli CataRhex3 in an in vitro Setting

Purpose

To evaluate the effect of each of the tip sizes available for the Oertli CataRhex3^® phacoemulsification machine on efficiency.

Methods

Porcine lenses were fixed in formalin for 2 hours, then cut into 3.0 mm cubes. We studied three Oertli tips, all of which had a 30-degree bevel: easyTip 2.2 mm (20G), easyTip 2.8 mm (19G), and CO-MICS (21G). For the 19G and 20G tips, vacuum was set at 600 mmHg, irrigation rate at 50 mL/min, continuous power 70%, and bottle height 85 cm. For the 21G tip, vacuum was set at 450 mmHg; irrigation and power settings were identical to those used for the easyTip tips. We measured time to removal and chatter events to determine efficiency.

Results

Results from 20 trials for each tip showed that the larger the gauge size, the more quickly lens fragments were removed. Chatter events demonstrated an increasing trend with smaller tip gauge. The 19G tip used an average time to fragment removal of 2.8 seconds; the 20G, 3.2 seconds; and the 21G, 4.6 seconds. Increasing tip diameter from 21G to 20G decreased emulsification time by 33% (P = 0.02). Increasing the diameter from 21G to 19G further decreased time to emulsification by 42% (P = 0.003). The 21G tip had a mean 1.4 events/cube; 20G, 0.35 events; and 19G, 0.1 events. Differences in mean chatter events for each tip were each statistically significant.

Conclusion

These data suggest that when evaluated by chatter events and emulsification time, the 2.8 mm (19G) easyTip proves to have greatest efficiency.

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.

Phacoemulsification in review: Optimization of cataract removal in an in vitro setting

Phacoemulsification, initially used in the late 1960s, continues to be the standard of care for cataract removal. An animal model was developed so that, in a controlled research setting, all the various machines, handpieces, tips, and settings could be investigated. As a general rule, the higher power, vacuum, and aspiration settings lead to optimally efficient phacoemulsification. In addition, both new phacoemulsification platforms and newly developed devices have been shown to improve efficiency. As a result, we recommend that the integration of these recent developments should be considered in future investigations.

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.