OBSOLETE: Ocular coloboma

Ocular coloboma is a developmental eye defect characterized by a gap or notch in one or more structures of the eye, resulting from incomplete closure of the embryonic optic fissure (also called the choroidal fissure) during early fetal development, typically around the fifth to seventh week of gestation. The condition can affect various ocular structures including the iris, ciliary body, zonules, retina, choroid, optic nerve, and/or eyelid. When the iris is involved, the pupil may have a characteristic keyhole or cat-eye appearance. Coloboma can be unilateral or bilateral and varies widely in severity — from a small iris notch with minimal visual impact to extensive chorioretinal or optic nerve colobomas that can cause significant visual impairment or even blindness. Microphthalmia (abnormally small eye) may also be associated. Ocular coloboma can occur as an isolated finding or as part of a broader genetic syndrome, such as CHARGE syndrome, cat-eye syndrome, Treacher Collins syndrome, or other chromosomal and single-gene disorders. The etiology is heterogeneous, involving mutations in genes such as PAX2, SHH, CHD7, MAF, GDF6, and others, as well as chromosomal abnormalities. Both genetic and environmental factors may contribute. Inheritance patterns vary depending on the underlying cause and may include autosomal dominant, autosomal recessive, or X-linked transmission, though many cases are sporadic. Note: This Orphanet entry (ORPHA:194) is marked as OBSOLETE, meaning it may have been reclassified, merged, or replaced by more specific disease entries within the Orphanet classification system. Patients and clinicians should refer to updated Orphanet entries for specific subtypes of coloboma or associated syndromes. There is no cure for ocular coloboma. Management focuses on regular ophthalmologic monitoring, correction of refractive errors, treatment of amblyopia in children, use of cosmetic contact lenses for iris colobomas, and surgical intervention in cases complicated by retinal detachment. Low-vision aids and educational support may be necessary for individuals with significant visual impairment.

Common questions about OBSOLETE: Ocular coloboma