IGF1 and retinal degeneration: However, these intraocular IGF-1 overexpressers also exhibited retinal degeneration, gliosis, and decreases in rod and cone function (Ruberte et al., 2004; Villacampa et al., 2013) similar to the global IGF-1 knockdowns, indicating that the role of IGF-1 in the retina is complex and levels are finely tuned.