Surgical Luminaires
Green Supplemental Surgical Lighting
Surgeons performing minimally invasive procedures found debilitating glare problems right from the start. The high intensity of standard surgical suite lighting causes poor visibility of cameras or microscopes, due to veiling reflections and the loss of contrast. This is caused by the supplemental light levels used for ordinary surgery which are specified at 200fc in order to minimize the transition from the surgical field which was typically 7500 to 10,000 foot-candles. However, because microscopes and cameras have their images displayed on monitors, they are now competing for the sensitivity of the surgeon's eyes. In this same era, surgical suite lights were all fluorescent with minimal options for dimming. For this new type of surgery it was hard to balance light levels for the surgeon, the anesthesiologist, and the support staff, creating difficulties, to perform their tasks. When adjusted for the surgeon, the support staffwould be working in less than optimal lighting causing a decline in efficiency and increase in potential for errors.
The patient's health and safety is crucial during surgery and is monitored accordingly.
Dedicated Green Lamps for Surgery
It was then GE emerged with the first dedicated green lamps for surgery called F40T12/G89. The "G89" stood for the color number of the LEE Filters green dyed sleeve secured to a GE white fluorescent lamp. After extensive research, GE chose this color for its spectral curve that closely matched the CIE curve of the human eye's sensitivity. It was discovered that by using a filtered lamp that was close to the eye's highest sensitivity, less light energy was needed to perform supplemental visual tasks such as reading instruments and charts. Monitors and scopes were also now easy to see in the reduced spectrum and intensity. The effect was that even though there was about 20-40 fc of green light it was perceived to be brighter than that. While there were many benefits to this method, it was quickly uncovered that the fixture performance suffered due to the dark green filters absorbing the white light when the fixture was used for ordinary surgery.
Lee Filters #89 Spectral Curve
Enter LED
When supplemental surgical fixtures transitioned to LEDs, we were given a better light source with higher purity and longer useful life. The native green LED makes its light directly through the chemistry of the LED. Not only does the purity of the LED allow for a more effective green light, it also supports the ability to have higher CRI white light for general surgeries as well as allowing a full range of illumination levels. The narrow bandwidth and improved performance of the LEDs increased the perceived light levels of the surgical space, improving visibility for everyone. Green LED light allows the specification community to have a much more simplified process when choosing a source that will provide light level sufficient enough to perform tasks such as reading labels, choosing instruments, and moving about the room while not creating contrast on the monitors. As a result, Green LED fixtures ensure the full surgical team is provided with the visual acuity needed without all the glare and visual fatigue.
Human eye sensitivity based on spectrum. Taken from the CIE 1931 standard. Relative Intensity
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