Congenital microcoria

Congenital microcoria is a rare inherited eye disorder characterized by abnormally small pupils (less than 2 mm in diameter) that show reduced or absent dilation in response to darkness or pharmacological mydriatic agents. The condition results from hypoplasia or absence of the dilator pupillae muscle of the iris, which is responsible for pupil dilation. It is also known as congenital miosis or hereditary microcoria. The condition is typically bilateral and present from birth. Congenital microcoria primarily affects the eye, specifically the iris. Patients often experience reduced visual acuity, increased sensitivity to glare, and difficulty adapting to low-light conditions due to the inability of the pupil to dilate adequately. Importantly, congenital microcoria can be associated with other ocular abnormalities, most notably juvenile-onset open-angle glaucoma and myopia. The association with glaucoma is clinically significant, as it may lead to progressive optic nerve damage and vision loss if not detected and managed early. Some families also show iris transillumination defects. The condition has been linked to mutations in the FOXC1 gene on chromosome 6p25, though genetic heterogeneity exists. There is no specific treatment to correct the underlying iris muscle defect. Management focuses on regular ophthalmological monitoring, particularly for the development of glaucoma, which may require medical or surgical intervention to control intraocular pressure. Corrective lenses may be prescribed for associated refractive errors. Genetic counseling is recommended for affected families.

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