Functions as a redox-dependent negative regulator of the Wnt signaling pathway. [protein]-dithiol + NAD(+) = [protein]-disulfide + H(+) + NADH [protein]-dithiol + NADP(+) = [protein]-disulfide + H(+) + NADPH Depletion causes significant defects in head formation with absence of eye structures. Belongs to the nucleoredoxin family.