Coloboma of the optic disc

Optic disc coloboma is a consequence of incomplete closure of the choroidal fissure. It is a rare condition, usually sporadic, but autosomal dominant inheritance also occurs. Optic disc colobomas are equally common in unilateral or bilateral lesions and may be accompanied by systemic manifestations.

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Symptoms of Optic Disc Coloboma

• Visual acuity is often reduced.
• A disc with a well-defined, focal, silvery-white, globular excavation that is displaced inferiorly so that the inferior neuroretinal rim is thinned or absent and normal disc tissue is contained within a small superior wedge.
• The disk can be enlarged.
• The retinal vessels are unchanged.

Visual field with superior defect which, in combination with the appearance of the disc, may be mistaken for normal tension glaucoma.

Ocular anomalies including microphthalmos and colobomas of the iris, ciliary body and choroid.

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Complications of optic disc coloboma

• Serous macular retinal detachment.
• Progressive widening of the excavation with thinning of the neural zonule despite normal intraocular pressure.
• Rhegmatogenous retinal detachment in eyes with associated chorioretinal colobomas.

Systemic lesions

Systemic lesions are quite numerous, so only the most important ones will be mentioned here.

1. Chromosomal abnormalities include Palau (trisomy 13), Edward (trisomy 18), and cat's eye (trisomy 12) syndromes.
2. CHARGE includes coloboma, heart defects, choanal atresia, retarded growth, and genital and ear anomalies.
3. Other syndromes: Meckel-Gruber, Goltz, Walker-Warburg, Goldenhar, Rubinstein-Taybi, Lenz microphthalmos, and Dandv-Walker cyst.

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