Septo-optic dysplasia (SOD) is a birth defect characterized by a malformed optic disk and nerve, pituitary deficiencies, and often the absence of the septum pellucidum, which is a layer of nerve tissue that separates the two lateral ventricles of the brain. Without the septum pellucidum, communication between the ventricles of the midbrain is impaired.
A rare developmental disorder of the brain and eye in which the optic disk and septum pellu-cidum do not develop normally, resulting in blindness, hormonal deficiencies, learning disabilities, decreased muscular tone, and, occasionally, seizures.