CircMKLN1 expression was reduced in RB tissues and cells. Elevated levels of circMKLN1 were linked to a better outcome in RB patients. In addition, circMKLN1 is a target gene for miR-425-5p. Silencing PDCD4 may improve the inhibitory roles of circMKLN1 in RB cell development and metastasis. Here, PDCD4 is linked to retinoblastoma.