AS A RULE hereditary degenerations of the cornea can be clearly distinguished from other corneal affections by their bilateral aspect, more or less typical morphology, and slow progression, with absence of vascularization. In addition, the fundamental criteria of all heredodegenerations apply equally to corneal degenerations: onset at approximately the same age in the different members of the family (homochronicity) and intrafamilial constancy of corneal alterations and of their evolution. However, their delimitation with regard to congenital malformations and certain inflammatory states is not always as simple as one would think, even when their characteristics have been quite clearly defined.
In fact, certain forms of interstitial keratitis, especially Hutchinson's keratitis, may be practically avascular, a feature which explains why certain infantile forms of corneal degeneration have been mistaken for manifestations of congenital syphilis. On the other hand, secondary vascularization in familial corneal degenerations is sometimes found, owing either to a chronic
FRANCESCHETTI A. CLASSIFICATION AND TREATMENT OF HEREDITARY CORNEAL DYSTROPHIES. AMA Arch Ophthalmol. 1954;52(1):1-12. doi:10.1001/archopht.1954.00920050003001