Congenital microcoria is an uncommon bilateral ophthalmological disease marked by the partial or complete absence of the dilator muscle of the pupil. At birth, infants have small pupils (< 2 mm) and a far away gaze. The disorder can cause malformations of the anterior part of the eye, leading to errors of refraction (myopia, astigmatism) and sometimes severe juvenile glaucoma. The iridocorneal angle may also be modified and the irides transilluminable. Apart from the lack of the dilator muscle, there is no other histological consequence. The disease is transmitted as an autosomal dominant trait. The gene causing the disorder is located on chromosome 13 (13q31-32) within a 3cM interval. Type TYRP2 intragenic markers, along with a candidate gene involved in the synthesis of melanin, provide very high Lod scores. They may help identify the gene and the disorders responsible for congenital microcoria. Treatment is symptomatic only.
Last update: July 2005