Nanosecond laser-assisted vs Ultrasound phacoemulsification: a long-term, contralateral endothelial cell study.

Abstract

Purpose : An alternative ultrasound phacoemulsification surgical technique for cataract surgery is evaluated. This technique utilizes novel coaxial nanosecond laser-assisted phacoemulsification. The purpose of this study was to contralaterally evaluate corneal endothelium cell density and morphology after coaxial ultrasound vs nano-second laser assisted phacoemulsification.

Methods : Eighty-two eyes subjected to uneventful cataract surgery with implantation of acrylic IOL. Each patient received ultrasound phacoemulsification (US) on one eye and coaxial nanosecond laser assisted (NL) on the other eye. Nuclear sclerosis was graded from NO3NC3 to NO4NC4 (Lens Opacities Classification System III).
Parameters analyzed pre-operatively and 2-years postoperatively: effective phacoemulsification time (EPT) for the US group and the number of laser pulses and total energy dissipated for cataract removal for the NL group. Endothelial cell density (ECD) and endothelial cell size variability were determined preoperatively and two years postoperatively. Endothelial structure was evaluated by measuring the central endothelial cell density (cells/mm²), coefficient of variation (CV) in cell size (an objective measure of polymegethism), and percentage of hexagonal cells, an index of pleomorphism (%HC).

Results : Mean EPT in the US group was 7.26±44 seconds. In the NL laser group average number of laser pulses was 243±188. Each laser pulse released 7.5 mJ (14 ns duration). The mean amount of energy dissipated into the anterior chamber was 1.83 J.
Mean ECD in the US group was preoperatively 2517±137 cells/mm² and 2-years postoperatively 2287±155 cells/mm2 (p<0.001). In the NL group preoperatively 2521±233 cells/mm² and 2-years postoperatively 2420±292 (p<0.001).
Mean CV in the US group was preoperatively 27.6±2.4 and 2-years postoperatively 30.6±2.4 (p<0.001). In the NL group, preoperatively 27.9±2.8 and 2-years postoperatively 27.2±2.0 (p<0.001).
Mean %HC in the US group was preoperatively 42.3±3.6 and 2-years postoperatively 37.74±3.54 (p<0.001). In the NL group, preoperatively 42.8±3.2 and 2-years postoperatively 43.00±2.68 (p<0.001).

Conclusions : Data in this study indicate that nanosecond laser-assisted cataract surgery phacoemulsification presents some advantages in comparison to ultrasound phacoemulsification in relation to endothelial cell structure preservation.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.