A novel method to compare phacoemulsification parameters in vivo: two halves of one nucleus.

BACKGROUND: Comparison of different phacoemulsification parameters remains a frequently debated and methodologically challenging area. The focus of this study was twofold: (1) To suggest an accurate and simple in vivo model for comparison of phaco parameters with the use of femtosecond laser technology. (2) To compare parameters of intelligent phaco (IP) torsional and combination ultrasound modes using the proposed model.

METHODS: Forty-three eyes underwent femtosecond laser-assisted cataract surgery (FLACS) with the precise division of each nucleus into two equal hemispheres. This approach was applied to compare two variants of phacoemulsification settings. In each case, one hemisphere was removed with the torsional ultrasound (US) with IP, while another hemisphere was evacuated with combination US. Aspiration time, cumulative dissipated energy (CDE), and fluid consumption were measured in all cases.

RESULTS: Our approach allows for direct comparison of different phacoemulsification parameters on each half of the same nucleus under identical surgical conditions. When comparison between torsional US with IP and combination US was made, without regard to nucleus density, no statistically significant difference in CDE, aspiration time, and fluid consumption was found. However, in soft cataracts, CDE was lower with the use of torsional US with IP, while aspiration time and fluid consumption demonstrated no proven differences. In hard cataracts, CDE and aspiration time were significantly lower with the use of the combination US mode.

CONCLUSIONS: The suggested approach of testing different types of phaco settings on equal halves of the same nucleus can be easily applied for quantitative comparisons under identical surgical conditions. The data obtained suggest that IP technology is preferable when compared to a combination US mode for soft lenses while the combined US is more suitable for hard nuclei.