Isolated microphthalmia-anophthalmia-coloboma

Isolated microphthalmia-anophthalmia-coloboma (MAC) is a group of closely related congenital eye malformations that occur without other systemic anomalies. Microphthalmia refers to an abnormally small eye, anophthalmia is the complete absence of one or both eyes, and coloboma is a gap or defect in one of the structures of the eye (such as the iris, retina, choroid, or optic disc) resulting from incomplete closure of the embryonic optic fissure. These conditions represent a spectrum of developmental eye defects that can affect one or both eyes and range from mild visual impairment to complete blindness. The term 'isolated' distinguishes this condition from syndromic forms where eye malformations occur alongside abnormalities in other organ systems. The condition is present at birth and is typically identified during neonatal examination or early infancy. Clinical features vary widely depending on severity: patients with coloboma may have relatively preserved vision or significant visual field defects, while those with anophthalmia have no light perception in the affected eye. Microphthalmia can range from mild reduction in eye size to severe forms where the eye is barely visible. Unilateral or bilateral involvement is possible, and different manifestations (e.g., microphthalmia in one eye and coloboma in the other) can coexist in the same individual. Several genes have been implicated in isolated MAC, including SOX2, OTX2, PAX6, VSX2, FOXE3, RAX, GDF6, GDF3, ALDH1A3, and STRA6, among others. Inheritance patterns vary depending on the causative gene and may be autosomal dominant, autosomal recessive, or X-linked. Sporadic cases also occur. There is no curative treatment; management is supportive and may include conformers or prosthetic eyes to promote normal orbital growth in anophthalmia or severe microphthalmia, surgical interventions for coloboma-related complications (such as retinal detachment), corrective lenses, and low-vision rehabilitation. Early intervention and regular ophthalmologic follow-up are essential to optimize visual outcomes and cosmetic appearance.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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