Studying the Safety of Femtosecond Laser Applications in Assisted Hatching Technology

Laser-assisted hatching (LAH) is used during in vitro fertilization (IVF) to improve the chances of embryo implantation into the uterine wall by creating a small, precise opening in its outer shell (zona pellucida). The primary objective of this study was to evaluate the safety profile of LAH performed using an infrared femtosecond laser system (λ = 1028 nm, E = 155 nJ, and I = 6.5 TW/cm2). We aimed to identify and quantify the potential biological effects of the laser and compare them with results from previous studies that used visible wavelength laser pulses (λ = 514 nm, E = 49 nJ, and I = 2.5 TW/cm2). To achieve this, we designed a controlled experiment using a mouse model. A critical component of our safety assessment involved quantifying the levels of reactive oxygen species (ROS) and analyzing the expression of heat-shock proteins (HSPs). Robust analyses revealed no statistically significant differences in either ROS production or HSP expression—assessed at both the protein and mRNA levels—between embryos in the negative control group and those subjected to the femtosecond LAH procedure. This key finding indicates that neither infrared nor visible femtosecond laser microsurgery of the zona pellucida induced a detectable oxidative or thermal stress response within the tested parameters.