Fine structural defects in a case of congenital microcoria.

A case of congenital miosis associated with myopia and cataract is described. Tissue obtained at iridectomy was examined with the electron microscope and compared with a specimen of normal iris. The miotic iris was found to be hypoplastic and to display differences in the cellular density of the stroma. The contractile processes of the dilator myoepithelium were conspicuously absent from the underlying stroma, and the existing myofibrils were much disarranged.