Medical photographic documentation is important for professional, research, and ethical concerns. This study analyzed the possible interference that the flash could cause on evaluation of lower eyelid cosmetic results. Standardized photographs with and without flash were taken of 10 patients with dermatochalasis. The photographs were evaluated by 3 independent observers, as before (without flash) and after (with flash) an alternative esthetic treatment of the lower eyelid. The observers rated the overall cosmetic improvement of the lower eyelid photographs on a visual analog scale. The 3 surgeons believed that there was improvement in cosmetic outcome from the first (without flash) to the second (with flash) picture. The results indicate that a simple flash addition in one of 2 consecutive photographs, taken seconds apart, could influence the impression of experienced surgeons on the final outcome of oculoplastic surgeries and may constitute a bias in observer-dependent studies.