Composed of nerve fibers that carry visual information from the retina to the brain. Optic nerve damage causes a loss of vision.
Optic Nerve Hypoplasia
(see article on Optic Nerve Hypoplasia)
A small and underdeveloped optic nerve. Optic nerve hypoplasia is one of the leading causes of vision loss and blindness in infants and children. Optic nerve hypoplasia occurs in the early stages of fetal development, when the eyes are forming. The optic nerve never fully develops or, once developed, dies-off and reduces in size for unknown reasons. Recent evidence suggests that ganglion cell axons, that make-up the optic nerve, are not able to grow through the optic nerve head because certain chemical messengers are not present for directional growth from the eye to the brain. Optic nerve hypoplasia is variable, and can result in only minor vision problems to complete blindness. Usually, if the infant has nystagmus the optic nerve hypoplasia is more severe and vision is very much reduced. If the infant does not have nystagmus, the likelihood for significant vision loss in less. All infants with optic nerve hypoplasia should have a CT scan or MRI to look for midline brain defects that can result in body growth problems. If the infant does not have nystagmus, the chance of midline brain defects is small. If the infant has nystagmus, the chance of midline defects is greater. Some infants have optic nerve hypoplasia in one eye only. If only in one eye, the chance of midline defects is very small and the doctor may chose not to do a CT scan or MRI, depending on other factors. There is no treatment or cure for optic nerve hypoplasia.
Optic Nerve Neuritis
An inflammation of the optic nerve usually with some loss of sight (may be temporary). It may signify a more serious neurological condition. A leading cause of optic neuritis is multiple sclerosis (MS).
Optic Nerve Disc
The visible part of the optic nerve inside the eye. The axons of the ganglion cells of the inner retina make-up the optic nerve (along with blood vessels as well as nerves coming from the brain to the eye).
A disease of the optic nerve in which the nerve fibers carrying the electrical impulses from the eye to the brain start to die off. In such cases the optic nerve has a pale or whitish appearance compared to the normal pink color. Optic atrophy is associated with poor reading vision and often the cause of legal blindness. May be associated with a serious medical condition and requires further medical examination to determine the cause of the atrophy. Not reversible. See Q and A Archives section about Optic atrophy.