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A pale disc is characteristic of long-standing optic neuropathy. In many cases, only one eye is affected and a person may not be aware of the loss of color vision until the examiner asks them to cover the healthy eye. Optic neuropathy is often called optic atrophy, to describe the loss of some or most of the fibers of the optic nerve.
Vision loss in dominant optic atrophy is due to optic nerve fiber loss from mitochondria dysfunction. Dominant optic atrophy is associated with mutation of the OPA1 gene [9] found on chromosome 3, region q28-qter. Also, 5 other chromosomal genes are described as causing optic atrophy: OPA2 (x-linked), OPA3 (dominant), OPA4 (dominant), OPA5 ...
Non-arteritic anterior ischemic optic neuropathy (NAION) is a medical condition characterized by loss of vision caused by damage to the optic nerve as a result of ischemia, or insufficient blood supply. The key symptom of NAION is optic disc swelling, which typically resolves within 2 months, but often leads to optic atrophy. The likelihood of ...
The optic tract syndrome is characterized by a contralateral, incongruous homonymous hemianopia, contralateral relative afferent pupillary defect (RAPD), and optic atrophy due to retrograde axonal degeneration. [16] Causes of optic tract lesions are also classified into intrinsic and extrinsic forms.
The optic disc may appear normal, swollen, or hyperemic in early stages. With hyperemia, disc hemorrhages may also be present. Continued damage to the optic nerve results in the development of optic atrophy, classically seen as temporal pallor of the optic disc.
Ischemic optic neuropathy (ION) is the loss of structure and function of a portion of the optic nerve due to obstruction of blood flow to the nerve (i.e. ischemia).Ischemic forms of optic neuropathy are typically classified as either anterior ischemic optic neuropathy or posterior ischemic optic neuropathy according to the part of the optic nerve that is affected.
This optic nerve must penetrate through the wall of the eye, and the hole to accommodate this is usually 20-30% larger than the nerve diameter. In some patients the optic nerve is nearly as large as the opening in the back of the eye, and the optic disc appears "crowded" when seen by ophthalmoscopy. A crowded disc is also referred to as a "disc ...
The mean disc diameter (DD) is (Vertical diameter of Disc+Horizontal diameter of Disc) divided by 2. The distance between the center of the disc and the macula is DM. Interpretation: When the ratio of DM to DD is greater than 3, ONH is suspected, and when it is greater than 4, Optic Nerve Hypoplasia is definite. [11]