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Optic nerves
Optic nerves Myelinated axons from the optic disk of each eye which join at the optic chiasm.
RELATED TERMS--------------------------------------
Disk
A round, flat structure, particularly the fibrous cartilage layer between two vertebrae (the bones that make up the spine). Also called intervertebral disk.
SIMILAR TERMS--------------------------------------
Optic atrophy
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.
Optic chiasm
Location where the optic nerve axons from the two retinae join and are reorganized into two separate groups (the optic tracts) that encode information about the right and left visual fields.
Optic 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.
Optic disk
Where the ganglion cell axon fibers leave the retina. Contains no photoreceptors and therefore creates a blind spot in the visual field.
Optic nerve
Sensory nerve that transmits impulses from the retina to the brain that become what we know as vision.
Optic nerve hypoplasia
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 neuritis
Optic 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 radiations
Projections from LGN to primary visual cortex (V1).
Optic tectum
Structure in the mid-brain of cold-blooded vertebrate that receives input from the optic nerve (homologous to the superior colliculi).
Optic tract
Retinal fibers leaving the optic chiasm separated by visual hemi-field (i.e. not by eye). Projects to three areas, the pretectum, the superior colliculus and the LGN.
Optical
Having to do with vision.
Optical power (of a lens)
Measure of how strongly a lens bends incoming rays. Measured in diopters and equal to the reciprocal of focal length. Human eye has an optical power of about 58.8 diopters.
Optician
A technician who fits a person for glasses. He/she does not test for glasses. Some opticians also fit contact lenses.
Opticrom
Opticrom is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): cromolyn sodium.
Optimark
Optimark is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): gadoversetamide.
Optimark in plastic container
Optimark in plastic container is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): gadoversetamide.
Optimine
Optimine is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): azatadine maleate.
Optipranolol
Optipranolol is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): metipranolol hydrochloride.
Optiray 160
Optiray 160 is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): ioversol.
Optiray 240
Optiray 240 is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): ioversol.
Optiray 300
Optiray 300 is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): ioversol.
Optiray 320
Optiray 320 is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): ioversol.
Optiray 350
Optiray 350 is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): ioversol.
Optison
Optison is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): albumin human.
Optivar
Optivar is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): azelastine hydrochloride.
PREVIOUS AND NEXT TERMS--------------------------------------
Off-Center cells
Decrease their activity when light increments are presented in their receptive fields. Surrounded by an antagonistic region which responds with the opposite polarity. Both ganglion and bipolar cells are separated into two classes, on-center and off-center. The off-center cells have dendrites that branch in the outer portion of the inner plexiform layer. See also On-Center Cells.
Opsin
Protein portion of rhodopsin.
Opthalmoscope
Device for seeing light reflected from the interior of the eye. First built by Hermann von Helmholtz.
Optic chiasm
Location where the optic nerve axons from the two retinae join and are reorganized into two separate groups (the optic tracts) that encode information about the right and left visual fields.
Optic disk
Where the ganglion cell axon fibers leave the retina. Contains no photoreceptors and therefore creates a blind spot in the visual field.
Optic nerves
Optic radiations
Projections from LGN to primary visual cortex (V1).
Optic tectum
Structure in the mid-brain of cold-blooded vertebrate that receives input from the optic nerve (homologous to the superior colliculi).
Optic tract
Retinal fibers leaving the optic chiasm separated by visual hemi-field (i.e. not by eye). Projects to three areas, the pretectum, the superior colliculus and the LGN.
Optical power (of a lens)
Measure of how strongly a lens bends incoming rays. Measured in diopters and equal to the reciprocal of focal length. Human eye has an optical power of about 58.8 diopters.
Optokinetic reflex
Elicited by coherent movement of a large region of the visual field. Helps stabilize the visual scene on the retina.
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