Investigating phototoxicity of optical coherence tomography (OCT) imaging in porcine and human sperm

Research question

Does exposure to near-infrared OCT laser radiation induce phototoxic effects in porcine and human sperm?

Design

Computer-assisted sperm analysis (CASA) was used to determine whether OCT laser illumination at or above levels typically used for imaging alters sperm motility. Flow cytometry was used to determine the impact of irradiation on sperm acrosome reaction status, DNA fragmentation, and membrane integrity. Additionally, in vitro time-lapse OCT imaging of a porcine cumulus-oocyte complex with irradiated sperm was performed to determine whether irradiated sperm interacts with and penetrates the cumulus oophorus. Finally, human sperm was irradiated and analysed using CASA and flow cytometric techniques.

Results

All irradiated samples showed no statistically significant difference in sperm DNA damage or CASA sperm motility parameters including average path velocity (VAP), straight line velocity (VSL) or curvilinear velocity (VCL) when compared to their matched manipulation control, suggesting that sample irradiation did not compromise spermatozoa viability even when using an optical power of more than one order of magnitude greater than that typically required to image embryos. Proof of concept OCT imaging suggested that the motility of the irradiated sperm during cumulus interaction was not affected by radiation.

Conclusions

There was no observed significant effect on boar and human sperm kinetics following near-infrared OCT laser radiation. Future work will be aimed at looking at the fertilisation process and embryo development following near-infrared OCT laser radiation.