The name "persistent hyperplastic primary vitreous" implies that eyes with this congenital anomaly contain a surplus of tissue, which has always been described as localized behind the lens and in the region of the canal of Cloquet (hyaloid canal). It will be demonstrated in this paper that the persistent hyperplastic primary vitreous is also present at a third site, which has not previously been described, namely, on the inner surface of the retina. This preretinal tissue originates in the neuroglial cells of the retina (cells of Müller), Clinical Symptoms The anomaly is clinically characterized by a unilateral leukocoria in a microphthalmic eye of a full-term baby. Opaque tissue is present just behind the lens and may vary in size from a small plaque to a membrane which completely covers the posterior surface of the lens. It is nearly always vascularized, and elongated ciliary processes extend toward or into the retrolental