CNTF and macular degeneration: For example, ciliary neurotrophic factor (CNTF), the best studied neurotrophic factor for retinal degenerations (Wen et al., 2012), has been investigated for a variety of neural degenerative diseases in the retina, including RP (Sieving et al., 2006; Talcott et al., 2011; Birch et al., 2013, 2016), macular degeneration (Zhang et al., 2011), and macular telangiectasia (Chew et al., 2015; Sallo et al., 2018).