Septo-Optic Dysplasia: A Changing Concept

Optic nerve hypoplasia is a congenital anomaly of unknown etiology that has become recognized as a major cause of blindness in children. Histologically, it is characterized by a subnormal number of optic nerve axons With normal mesodermal elements and glial supporting tissue. The ophthalmoscopic appearance is that of a small, gray or pale optic nerve head which is often surrounded by a yellowish mottled peripapillary halo, bordered on either side by a dark ring of pigment (double-ring sign). Retinal vascular tortuousity is also commonly seen. Visual acuity may range from 20/20 to no light perception, although all affected eyes will show localized visual field defects, often combined with a general narrowing of the fields. Since visual acuity is determined primarily by the integrity of the papillomacular nerve fiber bundle, it does not necessarily correlate with the overall size of the disc.