In the realm of medical lighting, whether surgical, veterinary, or dental, the term “lux” is used a lot. But what does it mean? Lux is a measure of light intensity (also called illuminance) and is the total amount of light that falls on a surface at a specified distance from the light source.
Just like speed is a measure of distance traveled over time, in medical lighting, lux conveys the intensity of light at a distance. When shopping or buying a medical lighting device, do you know what that distance is?
As anyone knows, the closer you are to a light, any light for that matter, the more intense it is. Many medical lighting manufacturers tout their high lux (or high intensity) lights, but doctors and practitioners may not know to ask — from what distance has that light been measured?
We’ve recently seen a high lux measurement promoted for a surgical headlight, but at an eight-inch working distance. Eight inches is not a sufficient distance to work on or examine a patient. Further, no doctor would use a medical headlight or examination light at a zero- or one-inch distance. That proximity would not give a practitioner any room to operate without bumping into the lighting device. And yet, some manufacturers actually boast their high lux settings at these undisclosed minimal distances.
Normal working distance is measured from the practitioner’s perspective; it begins at the bridge of the nose and extends to the work area. This is the perfect method for measuring the lux of a surgical headlight since the doctor wears the device. When positioned correctly, a surgical headlight will have the optics just up from the bridge of the nose.
While lux is the intensity the light device provides to illuminate the work area, its measurement should be aligned with the normal working distance of physicians and practitioners. The standard working distance is a range of 12 to 18 inches. That is why our light specifications are measured from a distance of 12 inches (not eight or fewer). We measure all our lighting devices at 12 inches from the light, so they are within the normal working distance of their practitioners.
At the highest power setting, the Magnum LED surgical headlight provides 75,000 lux at 12 inches. If we measured the lux of the Magnum at eight inches, just four inches closer, that number would jump to 145,000 lux. At an even closer distance of a mere four inches, it jumps to 500,000 lux. And yet, that working distance of eight or four inches is not viable. Yes, brightness and light intensity matter, but at what distance is the headlight you’re shopping for being measured?
Quality of Light
Beyond the brightness of a lighting device, another consideration is the quality of light. How is higher quality light made and how can a consumer distinguish quality from quantity?
Some surgical headlight manufacturers produce light from multiple LEDs within the optics. The problem with this method is that it produces a light field that can be filled with “artifacts” or variations. The field of light also has a “hotspot;” the result is that the light isn’t even edge to edge. It has a bright spot in the center with decreasing light intensity near the edge of the light spot thus producing a non-uniform overall light field.
IsoLux headlights are made with a single LED and an iris. There is no overlapping of the LEDs, thus eliminating hotspots and variations. This provides a smooth, even, high-quality light field from the outer edge to the center of the light. Our headlights yield a crisp, round light spot with distinct edges. These details together highlight the importance of the quality of the light over the quantity of light produced.
Don’t be fooled by high lux measurements boasted by medical lighting manufacturers until you understand the distance from which it has been measured along with the quality of light produced. Here at IsoLux, we believe in our products. Our design and quality are top notch, to give the finest quality of light to the surgeon or doctor at the time of procedure or examination.
IsoLux products are designed to deliver and to last. That is why we offer a five-year warranty on every surgical headlight we make. When shopping for medical lighting devices, be sure you understand the device specifications and how they’re measured.