Genetic defects or toxins can misdirect the embryonic forebrain-dividing process. One highly teratogenic alkaloid toxin that can cause<unk>  is<unk> mine or 2-deoxyjervine, found in the plant Veratrum californicum (also known as corn lily or false hellebore). Grazing animals are most likely to ingest this plant and induce<unk>  in offspring. People sometimes accidentally ingest false hellebore while pregnant, thinking it is hellebore, an unrelated plant which does not even resemble false hellebore, being recommended as a "natural" treatment for vomiting, cramps, and poor circulation, three conditions which may be present in the early stages of pregnancy.<unk>  occurs when certain proteins are inappropriately expressed, causing the brain to stay whole, rather than developing two distinct hemispheres. This leads to the fetus having one optic lobe and one olfactory lobe, resulting in the eye and nose malformations of<unk> . The Sonic Hedgehog (SHH) gene regulator is involved in the separation of the single eye field into two bilateral fields. Although not proven, it is thought that SHH emitted from the prechordal plate suppresses Pax6, which causes the eye field to divide into two. If the SHH gene is mutated, the result is<unk> , a single eye in the center of the face (Gilbert, 2000).
Cyclopia
Myopia
Diplopia
Nyctalopia
Entomopia
Hemeralopia
Ectopia 
Amblyopia