In phacoemulsification (phaco), 19 G tips are more efficient than 20 G and 21 G tips, irrespective of lens size, according to study findings published in Clinical Ophthalmology.

Researchers from the University of Utah compared 2 lens sizes, 3 tip sizes, and 2 ultrasound approaches on phaco efficiency and chatter. Porcine lens nuclei were soaked in formalin and then divided into cubes measuring 2.0 mm or 3.0 mm. Investigators obtained efficiency and chatter data for 30-degree bent 19 G, 20 G, and 21 G tips with a continuous torsional ultrasound system; and for straight 19 G, 20 G, and 21 G tips with a micropulse longitudinal ultrasound system. 

The researchers found that the average time necessary for removal was always higher for the 3.0 mm lens cube compared with the 2.0 mm lens cube. They observed statistically significant differences between the 19 G and 21 G tips with micropulse longitudinal ultrasound using a 2.0 mm cube and a 3.0 mm cube, as well as with continuous transversal ultrasound using a 2.0 mm lens cube and a 3.0 mm cube. No significant differences were observed between 19 G and 20 G tips with either cube size in both ultrasound systems. The research notes that 19 G tips performed better than 20 G and 21 G tips.


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A limitation of the study is the potential differences between hardened porcine lenses and human cataracts.  

“In summary, phaco is more efficient with larger tip diameters for relatively smaller and larger lens fragments,” investigators report. “Understanding these previously unknown relationships between the variables tested here is an important step in determining the balance between efficiency of removal, wound size, and tissue safety.”

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. This research was supported by the Research to Prevent Blindness and the University of Utah. Please see the original reference for a full list of disclosures. 

Reference

Ramshekar A, Heczko J, Bernhisel A, et al. Optimizing tip diameter in phacoemulsification of varying lens size: an in vitro study. Clin Ophthalmol. Published online November 17, 2021. doi:10.2147/OPTH.S333903