Two Cases of Congenital Fibrosis of the Extraocular Muleles

ABSTRACT

Congenital fibrosis of the extraocular muscle is characterized by the replacement of normal contractile muscles by fibrous tissue in varying degrees. Therefore, the clinical manifestation is dependent upon the degree of fibrous involvement. Brown reported 3 cases of the severe form of congenital fibrosis under the title of "General fibrosis syndrome". It has been known that the inferior rectus muscles are usually most prone to maximal involvement, which causes the eye to assume a hypotropic position with a chin elevation. We experienced two cases of congenital fibrosis of the extraocular muscles; one was a mild form with monocular involvement, and the other was a severe form with absence of all extraocular movement in the both eyes. In the latter, the histopathological examination of the excised tissue by light microscopy revealed that the inferior rectus muscle had a partly degeneration of some muscle fibers, as well as connective tissue proliferation. The lateral rectus muscle was replaced by fibrous tissue and fat cell. We discussed the clinical and histopathological features in the congenital fibrosis of the extraocular muscles.