RHO and cone-rod dystrophy: Cones are more severely affected than rods (Carr et al., 2021) and prom1-null frogs eventually develop a cone-rod dystrophy phenotype evidenced by loss of calbindin immunoreactivity, thinning of the inner plexiform layer, and progressive decreases in photopic ERG flicker function, whereas rod outer segments express rhodopsin and the scotopic ERG response remains intact.