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, 13 (2), e0192112

Utility and Safety of a Novel Surgical Microscope Laser Light Source


Utility and Safety of a Novel Surgical Microscope Laser Light Source

Taku Sato et al. PLoS One.


Objective: Tissue injuries caused by the thermal effects of xenon light microscopes have previously been reported. Due to this, the development of a safe microscope light source became a necessity. A newly developed laser light source is evaluated regarding its effectiveness and safety as an alternative to conventional xenon light source.

Methods: We developed and tested a new laser light source for surgical microscopes. Four experiments were conducted to compare xenon and laser lights: 1) visual luminance comparison, 2) luminous and light chromaticity measurements, 3) examination and analysis of visual fatigue, and 4) comparison of focal temperature elevation due to light source illumination using porcine muscle samples.

Results: Results revealed that the laser light could be used at a lower illumination value than the xenon light (p < 0.01). There was no significant difference in visual fatigue status between the laser light and the xenon light. The laser light was superior to the xenon light regarding luminous intensity and color chromaticity. The focal temperature elevation of the muscle samples was significantly higher when irradiated with xenon light in vitro than with laser light (p < 0.01).

Conclusion: The newly developed laser light source is more efficient and safer than a conventional xenon light source. It lacks harmful ultraviolet waves, has a longer lifespan, a lower focal temperature than that of other light sources, a wide range of brightness and color production, and improved safety for the user's vision. Further clinical trials are necessary to validate the impact of this new light source on the patient's outcome and prognosis.

Conflict of interest statement

Competing Interests: I have read the journal's policy and the authors of this manuscript have the following competing interests: Mr. Sugano is an employee of Mitsubishi Electric Engineering Co., Ltd. and has a competing financial interest. Mr. Sugano didn’t play any role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The provided fund granted his salary and the purchase of the research materials he used. This does not alter our adherence to PLOS ONE policies on sharing data and materials. All remaining authors have declared no conflicts of interest.


Fig 1
Fig 1. Laser light spectrum.
Four wavelengths: 464 nm (blue), 532 nm (green), 640 nm (red), and 785 nm (near-infrared) were used. There were no ultraviolet wavelengths.
Fig 2
Fig 2. Laser microscope setup details.
The diagram shows a conventional surgical microscope integrated with a laser light source from a laser generator allowing adjustment of color temperature levels and illuminance levels.
Fig 3
Fig 3. CIE1931 chromaticity diagram showing the range of colors of both xenon and laser light.
The color coordinates were measured by a luminance meter. The laser light shows a wider range than xenon light in the red and green zones.
Fig 4
Fig 4. Radar chart showing the range of luminance of both xenon and laser lights.
The laser light has a wider range of brightness than the xenon light, especially along the red and green color axes (cd/m2 = candela per square meter).
Fig 5
Fig 5. Illumination of each muscle sample by laser or xenon light at 150,000 lx for 30 min.
The temperature of the muscle under the xenon light was significantly higher than that under the laser light after 10, 20, and 30 min (all p < 0.01).

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Grant support

This study was supported by grants for the Development of Medical & Welfare Devices in Fukushima Prefecture (24-829). The funder provided support in the form of salaries for the co-author (TSU (Mr. Sugano)), but he did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.