Retinochoroidal Coloboma
Coloboma can be unilateral or bilateral
Bilateral colobomas are usually inherited in an autosomal dominant fashion
If fetal fissure fails to close posteriorly, then a coloboma affecting the retinal pigment epithelium, neurosensory retina or choroid may occur
Can be associated with lens coloboma due to persistence of mesodermal vascular remnants that prevent development of zonules in that area leading to flattening of the lens edge
Mutation in PAX6 gene has been reported in association with syndromic forms of colobomata.
FEATURES:
White background of the sclera usually showing a glistening white sheen replaces normal color of the fundus
Typically, coloboma is oval.
Usual location is downwards and inwards.
Posterior end frequently stops short of the disc
Anterior end sometimes reaches forwards beyond the limits of ophthalmic examination, due to involvement of the ciliary body region as well
Edges are pigmented
INVESTIGATIONS:
Systemic investigations or genetic tests for syndromes
USG - in hazy media
OCT - helps in identifying retinal breaks
MANAGEMENT:
Amblyopia:
Uniocular coloboma not involving the macula can be associated with refractive errors that need prompt correction to avoid development of amblyopia
In cases with bilateral coloboma, severe refractive errors may lead to ametropic amblyopia
RD is a frequent complication of choroidal colobomas
Prophylactic laser photocoagulation at the edge of coloboma
Surgery for RD usually involves pars plana vitrectomy, endolaser photocoagulation
Image from Rajan Eye Care Hospital
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