In the best of all possible worlds, every light box on the market should have undergone clinical trials to show its efficacy, and should provide customers with accurate technical information about the lamp’s characteristics (illuminance, spectrum, UV filter, etc). In the early days of light therapy, several companies did in fact develop first-generation light boxes together with the researchers, thus optimizing output and standardizing quality. With the success of the field, however, there was an explosion of new manufacturers, and it became sufficient for sales that light boxes merely fulfilled electrical standards. There was little collaboration with scientists to test new light box designs, and most often claims for efficacy and ocular safety were not based on any trials at all. It has become a “me-too” industry, with light boxes more a life-style device than a medical one. This is indeed a difficult situation for practitioners and patients alike.
CET’s Board of Directors and Advisors have developed a list of light box criteria. We need to observe certain standards to guide patients, doctors, and insurance companies. The CET Shop offers a specific device designed to the standards of clinical trials. A commission on sales helps to support our website.
Criteria for a light therapy device
The major factors to be considered are clinical efficacy, ocular and dermatologic safety, and visual comfort. Here is a checklist with recommended criteria for light box selection:
- INTENSITY: 10,000 lux illumination at a comfortable sitting distance. Many lamps attain this intensity only close up (for example, with eyes as close as 5 inches, or 13cm from the screen). Otherwise the glare can be overwhelming, forcing the user to look to the side, with illuminance reduced below the therapeutic range. Check the distance suggested carefully. Ask the manufacturer for calibration data, and whether a broad-field illuminometer was used.
- PRODUCT SPECIFICATIONS: Check if technical information is absent.
- UV FILTER: Fluorescent lamps should be fitted with a diffusing screen that filters ultraviolet (UV) rays that are harmful to the eyes and skin. Claims of UV protection are common, but questionable if a polycarbonate filter was not used.
- SPECTRUM: White light is preferable. “Full spectrum” lamps and blue (or bluish) lamps with color temperature above 5000 Kelvin are not superior in efficacy.
- ANGLE OF GAZE: The individual sits at a desk, usually looking down at reading matter or looking straight ahead. To avoid visual glare from the bright light, the lamp should project downward towards the eyes at an angle.
- SIZE OF LIT AREA: even though a small light box seems elegant and transportable, even small head movements diminish the wished-for therapeutic dose of light to the eyes.