Transcription factor that may function in dorsoventral specification of the forebrain. Required for closure of the choroid fissure and together with vax1 is required for optic nerve differentiation and to limit retinal development to the optic cup. Expressed in the anterior neural keel and later in the preoptic area, optic stalk and ventral retina. By 7 somites, detected in the anterior brain and expression is strong within the optic stalks, preoptic area and telencephalon by 12 somites. By 16 somites, expression in the telencephalon is reduced but that in the preoptic area, optic stalk and ventral retina remains and this pattern of expression is similar at 24 hpf (hours post-fertilization). By 48 hpf, expression is restricted to the ventral preoptic area, anterior dorsal hypothalamus and ventral retina. Belongs to the EMX homeobox family.