The cone visual cycle and its disorders: insights from zebrafish

Continuous vision relies on the recycling of visual pigment chromophore, which is photoisomerized during the process of vision. In vertebrates, this recycling is mediated by a complex network of biochemical reactions distributed across different cell types referred to as the visual cycle. In this review, we outline both historical and recent findings on the visual cycle and its connection to outer retinal dystrophies. Particular emphasis is placed on the recycling of cone, rather than rod, visual pigments, and on the utility of the zebrafish ( Danio rerio ) as a model for such studies.