Ocular pathology in trisomy 18. A histopathological report of three cases.

Ophthalmic histopathology is presented in three cases of trisomy 18. The children, who showed typical systemic anomalies, died in the first few days of life. In two cases the cornea was normal, while in one case hypercellularity of the stroma was found and Bowman's and Descemet's layers were absent. A minimal cataract was also present in two cases. Retinal folds were a common finding in the posterior region in all three cases. In one case, a partial coloboma of the optic disc was present in both eyes. In case 2, a pouch between the optic nerve and the dural sheath was considered to be a minimal developmental disturbance of the primitive epithelial papilla possibly representing an optic pit. The absence of pigment epithelium on the nasal disc border in case 3, also points to a deformity of the primitive papilla. The importance of the disc region in clinical and histopathological investigation is stressed.