Soluble PrPC in the aqueous and vitreous humor is probably released from lining cells, and is likely to play a protective role by binding amyloid-β, a proteolytic product of amyloid precursor protein implicated in the pathogenesis of glaucoma and age related macular degeneration (Anderson et al., 2004; Guillot-Sestier et al., 2009; Prakasam et al., 2010; Ratnayaka et al., 2015; Salazar et al., 2017; Shah et al., 2017). Here, APP is linked to age-related macular degeneration.