Glare is perhaps one of the biggest stumbling blocks for achieving a productive workspace. Glare occurs when a light source, or the reflection of a light source, is significantly brighter (generally more than three times brighter) than the ambient area surrounding it, causing visual discomfort.

The visual discomfort is the result of the human eye's inability to adapt appropriately to the extreme contrast in the light intensities within its field of vision. Adaptation is a chemical process that takes place on the surface of the retina, regulating the eye's sensitivity to light. In bright environments, this sensitivity decreases because more visual stimulus is available. In darker settings, sensitivities increase.

The change in sensitivity is uniform across the eye, leaving few options to compensate for hot spots and areas of irregularity. When the eye's sensitivity to light decreases to accommodate the brightest object in view, the surrounding areas become too lowly lit to be seen clearly. When the eye's sensitivity to light increases to interpret the dimmer surroundings, the intensity of the brighter object becomes glaring and uncomfortable.

Accommodation is the physiological response that compensates for shortcomings in adaptation. Accommodation is the muscular process that limits the amount of light entering the eye by constricting the pupil and squinting. People can also accommodate their visual environments by lowering their heads and furrowing their brows. This is often an unconscious, automatic response, like blinking when the eyes are dry.

More deliberate reflector design and advanced lens materials enable optical systems to offer better fixture efficiency and light control. Image courtesy of Prudential Lighting

In an office space, an employee could be subjected to glare for several hours nearly every day. Physically unable to adapt to glaring conditions, employees spend their days accommodating the visual environment with involuntary contractions of the pupil, squinting, changing the position of their head, and furrowing their brows. Repetitive use of these accommodation tactics can lead to stress injuries and muscle fatigue that manifest in the forms of eye strain, headaches, and computer vision syndrome. These problems are uncomfortable, fatiguing, and contribute to decreased productivity in the workplace.

Over the years, two common responses for combating glare in the commercial environment emerged. Less reflective, matte computer screens replaced their glossy predecessors in droves and fixture manufacturers added a pattern or opacity to the lens that more actively diffused the light and better obscured the lamp, in an attempt to eliminate glare-causing hot spots. Unfortunately, neither of these solutions did anything to improve the energy efficiency of the lighting system or to better project light into the areas where it was needed.

Today, rising energy costs and the public's renewed love affair with glossy screens have given specifiers a need for a new response to combat pesky glare. An ideal solution would simultaneously prevent glare, improve the efficiency of the light environment, and place the IESNA-recommended amount of light at the working level. Sophisticated optical systems, and the lighting fixtures that employ them, are the solution that allows a commercial environment to reinstate the vibrant glossy screens on a computer, tablet or smart phone, without sacrificing productivity to glare, and improving the overall efficiency of the lighting system.

It is with more deliberate reflector design and advancements in lens materials and technology that optical systems are now able to offer better fixture efficiency and light control. Reflectors, in more advanced optical systems, are precision built to reflect light from the lamp through the lens more effectively, minimizing the light energy wasted as the light bounces around within the fixture. Lenses have advanced from lamp dust jackets to powerful optical components. For example, a refractive lens is a lens that has been engineered with refractive prisms inside of it. These refractive prisms bend and distribute the light in a dramatically more controlled manner than the dumb or diffuse lenses previously used, making it possible to achieve IESNA-recommended light levels on the work plane and, at the same time, prevent the presence of unwanted or potentially glare-causing light elsewhere.

Reading Photometric Reports

While manufacturers can provide a copious amount of information on the specific lamp type, reflector, and lens material contained within a fixture, understanding how the components work together to distribute light requires additional information. Specifiers can use photometric reports to predict how a lighting fixture will perform in a space.