Neurodevelopmental disorders (NDDs) are a group of brain disorders such as autism spectrum disorder (ASD), attention-deficit hyperactivity disorder (ADHD), and intellectual disability (ID). NDDs have common symptoms such as difficulties in learning and speaking, poor concentration, and hyper- and hyposensitivity. Recent studies have reported de novo cytoplasmic FMR1-interacting protein 2 (CYFIP2) variants in NDDs accompanied by visual impairment. Cyfip2 was identified as an interacting partner of fragile X messenger ribonucleoprotein (FMRP), whose loss causes the failure of proper mRNA translation and subsequent protein synthesis, leading to abnormal synaptic connectivity and plasticity in the developing brain and finally to NDDs. Cyfip2 is also a component of the heteropentameric Wiskott-Aldrich syndrome protein family verprolin-homologous protein (WAVE) regulatory complex (WRC), which regulates actin polymerization, cytoskeletal remodeling, and the formation of neuronal morphology and synapses. In zebrafish, Cyfip2 is known to regulate proper optic tract axon sorting and retinal lamination. Furthermore, Cyfip2 deficiency alters the expression levels of a subset of genes related to transporters and channels and changes electrophysiological properties of ON ganglion cells in the mouse retina. This chapter describes recent advances in our understanding of the molecular mechanisms underlying NDD-related visual impairment, mainly focusing on Cyfip2 and Cyfip2-related genes.