Atlas of Ophthalmology

Bilateral Choroidal Coloboma with Unilateral Iridal Coloboma (Colour Photography Posterior Segment, Colour Photography Anterior Segment, SD-OCT)

المتلازمات الوراثية , الإعتلالات , التشوهات -> تشوه القرص البصري
Patient: 56 years of age, female BCVA 1.0 at OD; 0.1 at OS; IOP 15/16 mmHg General Medical History: -. Ocular Medical History: control of longlasting unilateral corectopia. Purpose: to show bilateral choroidal coloboma with unilateral iridal coloboma. Methods: Colour Photography Posterior Segment, Colour Photography Anterior Segment, SD-OCT. Findings: SD-OCT of OD and OS: bilateral choroidal coloboma. Colour Photography Posterior Segment of OD: coloboma located in the equatorial region with attached retina along the margin of the coloboma. Colour Photography Anterior Segment of OS: inferior corectopia upon light-induced miosis. Colour Photography Anterior Segment of OS: dilated pupil showing cataract, sectorial iridal coloboma and sectorial zonulalysis. SD-OCT of OD: margin of choroidal coloboma appearance of a hump owing to inward turning of the retinochoroidal layers, no thickening of the layers at the margin. Discussion: Ocular coloboma is a common malformation. It includes a spectrum of anomalies that ranges from iris coloboma to clinical anophthalmos. Coloboma is etiologically heterogeneous. The spectrum can vary from small colobomas located in the equatorial region that do not interfere with vision, to large colobomas involving the disc and macula with severe impairment of vision. Choroidal coloboma is a congenital defect caused by defective closure of embryonal fissure, which normally takes place during the 6th week of gestation. As an isolated defect, it is usually inherited as an autosomal dominant disorder, although autosomal recessive inheritance also occurs (1, 3). Gopal L et al. (2) described choroidal colobomas. Genetic as well as environmental causes have been proposed to cause an intrauterine insult that can lead to defective closure of the embryonal fissure leading to coloboma of the fundus (3). Histologically, the colobomatous area is deficient in normal choroid, retinal pigment epithelium, and the retina. Literature: (1) Pagon RA. Ocular coloboma. Surv Ophthalmol. 1981 Jan-Feb;25(4):223-36. (2) Gopal L, Khan B, Jain S, Prakash VS. A clinical and optical coherence tomography study of the margins of choroidal colobomas. Ophthalmology. 2007 Mar;114(3):571-80 (2) Gregory-Evans CY, Williams MJ, Halford S, Gregory-Evans K. Ocular coloboma: a reassessment in the age of molecular neuroscience J Med Genet, 41 (2004), pp. 881–891

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