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The white matter with hidden but MRI-visible damage is known as "Normal-appearing white matter" (NAWM) [136] and is where lesions appear. [22] The NAWM is considered a non-visible kind of lesion, produces disability and it is responsive to natalizumab [137] The pathology of the NAWM differs from areas near the lesions or near the cortex.
The fibers from the retina run along the optic nerve to nine primary visual nuclei in the brain, from which a major relay inputs into the primary visual cortex. A fundus photograph showing the back of the retina. The white circle is the beginning of the optic nerve. The optic nerve is composed of retinal ganglion cell axons and glia.
Additional MRI findings for absent/unknown AQP4-IgG Optic neuritis: Either 1) brain MRI showing normal findings or only nonspecific white matter lesions, or 2) optic nerve MRI showing T2-hyperintensity, or T1 enhancing lesion, greater than 1/2 optic nerve length or involving optic chiasm Acute myelitis
The optic tract is a continuation of the optic nerve that relays information from the optic chiasm to the ipsilateral lateral geniculate nucleus (LGN), pretectal nuclei, and superior colliculus. [14] The optic tract represents the first stage in the visual pathway in which visual information is transferred in a homonymous nature. [ 15 ]
In megalopapilla the optic disc diameter exceeds 2.1 mm (or surface area more than 2.5 mm 2 [1]) with an increased cup-to-disc ratio. [2] Although the optic disc is looks abnormal, the disc colour, sharpness of disc margin, rim volume, configuration of blood vessels and intraocular pressure will be normal.
The original Amsler grid was black and white. A color version with a blue and yellow grid is more sensitive and can be used to test for a wide variety of visual pathway abnormalities, including those associated with the retina, the optic nerve , and the pituitary gland .
The light circle is the optic disc where the optic nerve exits the retina. The visual system in the human brain is too slow to process information if images are slipping across the retina at more than a few degrees per second. [28] Thus, to be able to see while moving, the brain must compensate for the motion of the head by turning the eyes.
In patients with headaches, the finding of swollen optic discs, or papilloedema, on fundus photography is a key sign, as this indicates raised intracranial pressure (ICP) which could be due to hydrocephalus, benign intracranial hypertension (aka pseudotumour cerebri) or brain tumor, amongst other conditions. Cupped optic discs are seen in glaucoma.