Optimizing laser irradiation: An in-silico meta-analysis of skin discoloration treatment

In recent years, the application of picosecond laser (PSL) treatment for skin discoloration caused by nevus of Ota has been advancing in the fields of dermatology, plastic surgery, and cosmetic surgery. However, setting appropriate irradiation conditions is necessary to achieve effectiveness. This poses a challenge as previous meta-analyses on laser treatment research did not account for proper laser irradiation levels. Further, such analyses included results from cases with over- and under-irradiation, prompting the need for a more accurate evaluation.

A research team led by Postdoctoral Fellow Yu Shimojo, Specially Appointed Professor Toshiyuki Ozawa, and Professor Daisuke Tsuruta from the Graduate School of Medicine developed the EICF (Excessive Setting Index of Clinical Fluence) indicator using an in-silico mathematical model to determine the appropriate laser irradiation conditions. Based on this index, the irradiation parameters used in clinical practice were evaluated. The team then conducted a meta-analysis on treatment studies that were consistent with theoretical irradiation conditions.

In the case of nevus of Ota, a comparison of PSL and nanosecond laser (NSL) treatments revealed that PSL treatment demonstrated higher efficacy and equivalent safety under proper conditions.

“This achievement provides scientific evidence that answers questions such as ‘Why was it effective?’ and ‘Why did side effects occur?’ in PSL treatment,” said Dr. Shimojo. He concluded, “Although further verification is needed, we hope EICF can be used to ensure safer and more effective laser irradiation conditions.”

Reference:

Shimojo, Yu et al. Association between irradiation parameters and outcomes for picosecond laser treatment of nevus of Ota: An in-silico-supported meta-analysis, JAAD Reviews, DOI: 10.1016/j.jdrv.2025.06.001