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An optic nerve melanocytoma is a tumor made up of melanocytes and melanin. Melanocytomas are typically a benign meaning they can grow, but rarely transform into a malignancy. Even so, local growth can affect adjacent tissues. Most optic nerve melanocytomas are small, black, and do not grow.
Optic nerve sheath meningiomas (ONSM) are rare benign tumors of the optic nerve. 60–70% of cases occur in middle age females, and is more common in older adults (mean age 44.7 years). It is also seen in children, but this is rare. The tumors grow from cells that surround the optic nerve, and as the tumor grows, it compresses the optic nerve.
Optic nerve (the nerve that connects the eye to the brain) A person can have coloboma in one or both eyes, and they may impact vision, depending on where they’re located, the U.S. National ...
A coloboma (from the Greek κολόβωμα, meaning "defect") [1] is a hole in one of the structures of the eye, such as the iris, retina, choroid, or optic disc.The hole is present from birth and can be caused when a gap called the choroid fissure, which is present during early stages of prenatal development, fails to close up completely before a child is born.
Coloboma of optic nerve is a rare defect of the optic nerve that causes moderate to severe visual field defects. Coloboma of the optic nerve is a congenital anomaly of the optic disc in which there is a defect of the inferior aspect of the optic nerve. The issue stems from incomplete closure of the embryonic fissure while in utero.
Ocular disc dysplasia is the most notable ocular defect of the disease. An abnormal development in the optic stalk causes optic disc dysplasia, which is caused by a mutation in the Pax2 gene. [4] The nerve head typically resembles the morning glory disc anomaly, but has also been described as a coloboma. [4]
One important variety of bilateral scotoma may occur when a pituitary tumour begins to compress the optic chiasm (as distinct from a single optic nerve) and produces a bitemporal paracentral scotoma, and later, when the tumor enlarges, the scotomas extend out to the periphery to cause the characteristic bitemporal hemianopsia.
Optic pits are associated with other abnormalities of the optic nerve including large optic nerve size, large inferior colobomas of the optic disc, and colobomas of the retina. The optic disc originates from the optic cup when the optic vesicle invaginates and forms an embryonic fissure (or groove). Optic pits may develop due to failure of the ...