OBJETIVO: A proposta deste estudo é descrever e analisar o comportamento palpebral após escuridão abrupta em indivíduos normais. MÉTODOS: Foram captadas imagens das pálpebras em ambiente claro e após escurecimento total. Os grupos foram crianças com idades entre 2 a 11 meses, 22 a 36 meses e adultos entre 19 e 61 anos. A distância entre o centro pupilar e a margem palpebral superior foi medida nas duas imagens. RESULTADOS: Houve elevação da pálpebra superior após privação de luz em todos os indivíduos, sendo que nas crianças houve maior amplitude. CONCLUSÕES: A privação de luz provoca elevação transitória da pálpebra superior em crianças e adultos.

PURPOSE: To determine if the resting position of the upper eyelid is affected by darkness. METHODS: Palpebral fissure images of normal subjects were acquired in photopic conditions and in total darkness. The subjects were divided in to three groups aged 2-11 months, 22-36 months and 19-61 years. The first palpebral fissure image was acquired in photopic conditions. The lights were then turned off and a second image of the same eye was obtained in total darkness. For both images the distance between the midpupil and upper eyelid margin was measured. RESULTS: Darkness increased this distance in all subjects. The increment in palpebral position was greater in children. CONCLUSION: Darkness provoked upper eyelid retraction in all subjects tested. This effect probably results from stimulation of the sympathetic tone to Müller's muscle.