![]() 5 In 85% of cases, the optic nerve with the pit is larger than the fellow optic nerve. They appear as grey, yellow or black excavations in the optic disc and are unilateral 95% of the time ( figure 5). Optic pits are best seen clinically on dilated fundus evaluation and OCT imaging. 5 This can lead to visual field defects, particularly if the anomalies displace nerve fibers. 5 Optic nerve pits are relatively rare, with an overall incidence of one in 11,000.Ĭircumpapillary chorioretinal atrophy with associated retinal pigment epithelium changes are commonly seen in those with optic nerve pits––especially if the pit is located near the disc margin. 5 There are no known systemic or gender associations however, a higher incidence of optic nerve pits is observed in those with basal encephalocele. They are believed to occur during the first trimester of gestation, are usually less than one-half disc diameter in size and are more commonly located temporally. Optic nerve pits are congenital abnormalities of the optic nerve due to incomplete closure of the fetal fissure.Key clinical findings here include defined refractile aggregates, the presence of spontaneous venous pulsation and the absence of Paton’s lines. It is important to differentiate optic nerve head drusen from acquired bilateral disc edema or papilledema. Multiple focal, round, hyper-reflective masses with significant elevation. And, because optic nerve head drusen also may exhibit considerable elevation, they are best visualized with optical coherence tomography ( figure 4).Ĥ. ![]() Adjunctive photographing techniques, such as fundus autofluorescence, may make the drusen appear more pronounced ( figures 2 and 3). Optic nerve head drusen are often bilateral and have no Such drusen are not usually visible at an early age, are said to be “buried” and appear to enlarge throughout life as they move closer to the surface and become more visible. The nerve itself is characteristically small and appears crowded. 1 Anomalous blood vessel patterns frequently are visible. 4 Ophthalmoloscopically, they appear as multiple, round to irregular, whitish-yellow dots within the surface of the nerve. Optic nerve head drusen are multilobed, globular concretions of calcium, amino and nucleic acids, mucopolysaccharides and sometimes iron.Because associated kidney diseases are potentially life threatening, individuals diagnosed with optic nerve colobomas should have a renal ultrasound. It is important to note the potential association of optic disc colobomas with renal coloboma syndrome, which may cause devastating kidney problems. Further, patients with optic disc colobomas commonly experience significant refractive error and anisometropia. Often, there can be associated colobomas of the iris and/or ciliary body. Optic nerve head drusen located at approximately 12 o'clock, with a highlighted appearance on fundus autofluorescence (right). They can occur either unilaterally or bilaterally, with equal frequency. Optic disc colobomas appear as sharply defined, white, bowl-shaped, inferiorly decentered excavations.1 They present bilaterally in 80% of patients. Tilted discs are characterized by an elevation of the superotemporal disc, posterior displacement of the inferonasal disc and situs inversus of the retinal vessels.2 Although considered benign neoplasms, 1% to 2% of melanocytomas can transform into malignant melanoma. 2 From a demographic standpoint, approximately two-thirds of all presentations are documented in whites, with just one-third seen in blacks. Melanocytomas usually are located inferiorly on the optic nerve head, and up to 60% of cases involve either the retina or choroid. 2 Their mean thickness is approximately 1.0mm however, they may be noticeably elevated. Pigmented black or dark brown lesions that obscure all or part of the optic disc ( figure 1). Melanocytomas are characteristically unilateral, very deeply.Acquired abnormalities are assumed to be pathologic, and generally are described with respect to optic nerve’s reaction to a given insult (i.e., cupping, swelling or atrophy). Congenital anomalies can be further subdivided into benign or pathologic. Optic nerve anomalies can be categorized as congenital or acquired. This is because certain irregularities may require additional testing and/or intervention. When optic nerve abnormalities are detected, it is essential to differentiate between anatomical and pathological causes. Melanocytoma with adjacent choroidal, retinal components and mild yellow exudation. The horizontal diameter of a typical optic nerve is approximately 1.5mm. Its potential permutations are diverse, with individualized variations in color, size and even vascular supply.Ī normal optic nerve head (ONH) usually is round or oval, mildly elevated and pink in color, with a centralized depression known as the cup. Examining the optic nerve can be a daunting task.
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