Impact of lens densitometry on phacoemulsification parameters and usage of ultrasound energy in femtosecond laser-assisted lens surgery

Objective: The aim of this study was to find the correlation between lens densitometry measurements using Pentacam Scheimpflug imaging system with equivalent average ultrasound power and cumulative dissipated energy (CDE) in femtosecond laser-assisted lens surgery (FLALS). Methods: One hundred and twenty-four eyes were analyzed retrospectively, of which 109 had undergone cataract surgery and 15 had received refractive lens exchange with FLALS. Using the Pentacam Nucleus Staging (PNS) lens densitometry program, preoperative mean lens density and cataract grading score were evaluated. Average ultrasound power and CDE were recorded during surgery and correlated with the PNS grading and average lens density value. Exclusion criteria included small pupil size, previous ocular surgeries, tumors, optic atrophy, corneal scarring, intraoperative capsular rupture, and zonular dehiscence. Results: Preoperative average lens density compared with CDE showed a weak significant positive linear correlation (p < 0.0001). CDE increased as lens density increased. This was also noticed when CDE and ultrasound time were compared with the PNS grading, demonstrating a significant moderate correlation (p < 0.0001). With increasing average lens density, the equivalent average ultrasound power showed a positive correlation (p < 0.0001). A weak positive correlation between estimated fluid use and PNS was also observed (p < 0.0001). Forty-one cases that did not require ultrasound energy during phacoemulsification had a PNS score between 0 and 1. Conclusions: The Centurion Phacoemulsification machine has been shown to correlate positively with the Pentacam Scheimpflug System offering an objective and repeatable measure of lens density and cataract grading. This can aid in intraoperative phacodynamics and help reduce phacoemulsification complications, such as corneal endothelial injury.