Thermal effects in laser-assisted pre-embryo zona drilling

Area of Science:

• Biomedical Engineering
• Reproductive Biology
• Laser Physics

Background:

• Diode lasers (1480 nm) are utilized in assisted reproductive technologies.
• Zona pellucida dissection is crucial for embryo biopsy and hatching.
• Precise laser application is necessary to avoid thermal damage to pre-embryo cells.

Purpose of the Study:

• To investigate the thermal effects of diode laser ablation on the zona pellucida.
• To define safe laser operating parameters for in vitro fertilization.
• To optimize laser settings for zona pellucida dissection without compromising embryo viability.

Main Methods:

• In vitro fertilization procedures using diode lasers (1480 nm) for zona pellucida ablation.
• Animal models were used to demonstrate and measure zona pellucida ablation.
• A crossed-beam experiment with a HeNe laser probe measured temperature-induced refractive index changes to estimate thermal gradients.

Main Results:

• Diode laser application creates channels in the zona pellucida, facilitating biopsy and hatching.
• Superheated water (approaching 200°C) was observed on the laser beam axis.
• Thermal histories were mapped for regions surrounding the laser beam.

Conclusions:

• Safe laser regimes for zona pellucida ablation require careful control of pulse duration and power.
• Optimal parameters identified: pulse duration ≤5 ms and laser power approximately 100 mW.
• These findings contribute to safer and more effective assisted reproductive technologies.