In the operating room (OR), precision, visibility, and attention to detail are big components of successful surgical outcomes.

We all know how important having great surgical lights is, but how do the colour temperatures of the light our docs select change things? Colour temperatures aren’t just about visibility; they are critical to enhancing the surgeon’s ability to distinguish tissues, reduce eye strain, and improve overall efficiency.

This article explains why different colour temperatures are needed in surgery and what each colour temperature represents, separating the roles of room lighting and surgical lighting.

The role of light in surgery

Before discussing specific colour temperatures, it’s important to understand the fundamental role of light in surgery. In an OR, there are two primary types of lighting: room lighting and surgical lighting. Each serves a distinct purpose and contributes to the overall environment in the operating room.

Room lighting

Room lighting is the general illumination that lights up the entire OR space. This type of lighting ensures that the surgical team can move safely and see their surroundings. It is typically uniform and provides a baseline brightness level across the room.

Room lighting is usually designed to minimise shadows and reduce glare, creating a comfortable working environment. However, it does not focus directly on the surgical site and is not intended to highlight specific anatomical details. The colour temperature of room lighting is generally chosen to create a natural and soothing environment, often resembling daylight, to keep the surgical team alert and reduce fatigue.

Surgical lighting

Surgical lighting, on the other hand, is highly specialised and focuses directly on the surgical site. These lights are much brighter and more concentrated than room lighting, designed to provide intense illumination that enhances the visibility of the patient’s anatomy.

Surgeons rely heavily on surgical lighting to make precise incisions, identify tissues, and perform complex procedures. High-quality surgical lighting minimises shadows on the surgical field and can be adjusted for intensity and colour temperature to suit the needs of specific procedures.

However, not all tissues are the same colour, and not all lighting is created equal. Different wavelengths of light can penetrate tissues to varying degrees, highlighting specific structures and improving contrast. This is where the colour temperature of surgical lighting comes into play.

Colour temperature measurements

According to AJ Knulst in the Standards and Performance Indicators for Surgical Luminaires colour temperature, expressed in Kelvins (K), is a scale that measures the colour of light a lamp produces.

This scale is based on the colour changes observed in a piece of steel (referred to as a black body) as it is heated to specific temperatures. As the steel’s temperature increases, it glows in various colours, starting with red, moving through amber, then white, and finally reaching a bluish-white hue. Light sources with a colour temperature above 5000K are categorised as “cool colours,” which have a bluish tint. In contrast, those with lower colour temperatures, between 2700K and 3000K, are known as “warm colours,” having a yellowish appearance, and are typically used for red tissue.

In surgical lighting, colour temperatures typically range from 3,000K to 6,700K. This range provides colour-neutral illumination that enhances visibility and aids in accurate diagnostics.

White light: the standard for general visibility

White light is the most used colour temperature in surgical settings. It combines all visible wavelengths, providing a balanced illumination that closely mimics natural daylight. This is important because it offers a true-to-life view of the surgical field, allowing surgeons to distinguish between different tissues, such as skin, fat, muscle, and blood vessels. It is easiest to see bone.

The whites range from cool white for heightened clarity in intricate procedures to warm white.

White light is versatile and suitable for most general surgeries. It provides the broad spectrum needed to differentiate tissue colours, making it easier for surgeons to identify anomalies and perform procedures precisely.

Blue light: enhancing contrast and visual acuity

Blue light, with its shorter wavelength, is particularly effective in enhancing the contrast between tissues, especially in highly vascular areas. It makes red-coloured tissues, such as blood vessels, stand out more prominently. This is especially useful during cardiovascular procedures, where clear visibility of blood flow and vessel structure is critical.

Moreover, blue light can help reduce eye fatigue during long surgeries. When exposed to blue light, surgeons are less likely to experience visual strain, which maintains clarity and sharpness without overwhelming the eyes.

Green light: reducing glare and enhancing comfort

Green light is another important colour temperature in the surgical lighting spectrum. It is often used with white light to reduce glare and improve the surgeon’s comfort. Green light is less harsh on the eyes and helps reduce the surgical field’s overall brightness without compromising visibility.

Green lighting is occasionally used in OR room lighting to create a calming atmosphere and to balance the intensity of surgical lighting. While not as critical as surgical lighting, green room lighting helps minimize overall brightness and visual strain, particularly during longer procedures.

Red light: minimising light reflection in retinal surgery

Red light, though less commonly used, has a specific application in eye surgeries, particularly retinal surgery. Its longer wavelength means it is less likely to be reflected by the retina, which reduces the risk of phototoxic damage to the eye.

By using red light, surgeons can minimise the amount of light reflected back into their eyes, reducing glare and improving the precision of delicate manoeuvres in retinal procedures. This makes red light an invaluable tool in ophthalmic surgeries where accuracy is crucial.

Yellow light: optimal for soft tissue differentiation

Yellow light balances the harshness of white light and the contrast provided by blue light. It is particularly useful in soft tissue surgeries where distinguishing between different layers is critical. Yellow light enhances the visibility of soft tissues, making it easier for surgeons to identify and differentiate between various structures.

The use of different light colour temperatures in both room and surgical lighting is far more than a matter of preference or aesthetics; it’s a strategic choice that enhances surgical precision, reduces eye strain, and improves patient outcomes. Each colour temperature plays a unique role, from providing general visibility in the room to improving contrast and reducing glare directly at the surgical site. By understanding the importance of these different wavelengths, surgical teams can optimise their lighting environments to ensure the highest standards of care.

Our innovative surgical lighting solutions are designed with these needs in mind, offering customizable options that allow surgical teams to tailor their lighting to the specific requirements of each procedure. By investing in the right lighting, your hospital can enhance both the surgeon’s experience and the quality of patient care.

To find out more about our range of surgical lights, please get in touch with our team.

Originally published by Skytron. Cubro is the authorised distributor of Skytron lights and pendants in New Zealand.