Contributor: Gordon K. Klintworth
Microphthalmos (microphthalmus, microphthalmia) may be associated with intrauterine fetal infection (such as rubella rubella - congenital]).  The small eye is accompanied by microcornea. Other ocular developmental abnormalities are often associated, such as a coloboma of the iris [coloboma - iris], ciliary body [coloboma - ciliary body], choroid [coloboma - choroid], retina [coloboma - retina] and even of the optic nerve [coloboma - optic nerve]. These colobomas  follow a failure of the fetal fissure to close properly. Major defects in closure of the posterior aspect of the fetal fissure can result in evagination and cystic outpouching of the posteroinferior uvea, retina, and sclera (microphthalmos with cyst).  Microphthalmos may be inherited as an autosomal recessive [microphthalmos - autosomal recessive] or autosomal dominant [microphthalmos - autosomal dominant] disorder. Microphthalmos may be associated with Meyer-Schwickerarth-Weyer syndrome, MIDAS syndrome, Lenz syndrome, Matthew-Wood syndrome and many other syndromes. Severe microphthamos can result from certain mutations in the PAX6, SOX2 and STRA6 genes. With the PAX6 gene mutations it may be a consequence of an absence of lens development.