This study investigated the effect of visible light exposure on retinal pigment epithelium (RPE). The activation of Wnt/beta-catenin pathway was investigated by immunofluorescence and Western blot analysis using human retinal pigment epithelial (ARPE-19) cells, which demonstrated that the exposure of white light induced the activation of the Wnt/beta-catenin pathway. Real time RT-PCR demonstrated that the mRNA of alpha-smooth muscle actin (alpha-SMA), and vimentin increased 2.5-4-fold and that of zona occludens 1 (ZO-1) decreased approximately 0.8-fold after white light exposure. The up-regulation of vimentin expression and the down-regulation of ZO-1 were evident by Western blot analysis and immunohistochemistry. Moreover, the ability of phagocytosis of ARPE-19 cells decreased 0.6-fold after light exposure. Together, white light exposure was Supposed to induce the activation of Wnt/beta-catenin pathway, the changes in the expression markers of epithelial and mesenchymal cells in RPE cells, and the concomitant impairment of the ability of phagocytosis. (C) 2008 Elsevier Inc. All rights reserved.