Also, Xu and their group showed that in Rb deficient retinal cells, CD133 expression was strong in maturing photoreceptors and weak in the retinal progenitor cell population [20]. Studies have shown that CD133 (Prominin) is crucial for photoreceptor outer segment morphogenesis and the mutations within the gene is associated with several retinal dystrophies which ascertains its pivotal role in the visual cycle [31]. This evidence concerns the gene RB1 and inherited retinal dystrophy.