In addition to testing AMD-relevant bioactivity, we investigated the effect of this fucoidan on important functions of the RPE, assessing survival, phagocytosis, barrier properties, and the expression of a protein important for the visual cycle (retinal pigment epithelium 65 kDa protein, RPE65) [27] and complement inhibition (protectin, CD59) [28]. Here, RPE65 is linked to age-related macular degeneration.