OPN1SW and retinal degeneration: Although there was mild retinal iron accumulation, as indicated by decreased Tfrc mRNA levels, in the mice after 7 months of exposure to high systemic iron, and in the aged mice after 4 months of exposure to high systemic iron, there was no retinal degeneration except for a mild reduction in Opn1sw mRNA in the 9-month FeDex-injected mice.