Energy Focus, Inc. announced its new 500D series tubular LED lighting products are the first in the U.S. verified as “Low Optical Flicker, Less Than 1%” by UL. The designation confirms Energy Focus' status as an innovator of LED lighting technology and commitment to developing flicker-free lighting. Optical flicker is any fluctuations in brightness over time.  Flicker of sufficiently low frequency can be visually perceived as blinking or flashing.  Higher frequency flicker is invisible to the human eye but puts stress on the human brain as it processes visuals, and is a known cause of headache and eyestrain.   People who have visual hypersensitivity, especially those on the autism spectrum, are susceptible to adverse reactions to fluctuations in light. People with photosensitive epilepsy may experience seizures from flickering light. While LEDs are capable of flicker-free lighting, flicker is often present as a result of low-quality drivers having output current ripple.  By engineering driver to remove current ripple, Energy Focus products ensures practically flicker-free operation that avoids potential flicker-induced health risks. UL Verification is an objective, science-based assessment that confirms the accuracy of marketing claims.  The flicker marketing claim Verification service was created in response to new requirements in California Title 24, a new standard designed to reduce commercial and residential energy consumption, for reduced-flicker lighting, as well as address market demand for third-party verified flicker results. This test measures all types of flicker, including frequencies of flicker higher than what the eye can “see” as flashing or blinking, but also the higher frequency, invisible flicker.