Corneal Dysgeneses, Dystrophies, and Degenerations

Abstract

Dysgeneses, dystrophies, and degenerations of the cornea account for a broad spectrum of ocular abnormalities, ranging from clinical curiosities to sight-threatening anomalies. Knowledge of these entities traditionally accrued through clinical study and examination of histopathologic specimens. Within the past decades, discoveries of the specific gene mutations for corneal stromal dystrophies have greatly advanced understanding of these corneal disorders, and in some cases have modified their classification.

Dysgeneses of the cornea are developmental disorders, sometimes inherited, resulting in congenital malformations. Corneal dysgeneses may be unilateral or bilateral and are nonprogressive. The central, peripheral, or entire cornea, as well as other ocular structures, may be affected. Occasionally, associated systemic abnormalities are present.

A corneal dystrophy generally exhibits a familial pattern, is bilateral if not symmetric, is associated with a genetic locus, and does not appear to be secondary to any environmental or systemic factor. Dystrophies tend to manifest relatively early in life and are variably progressive. Abnormalities generally affect the central cornea and are noninflammatory in origin. Senescence may encourage deterioration of the dystrophic cornea but is not a primary cause of the disorder. Each unique dystrophy exhibits characteristic histopathologic features. Degenerations of the cornea occur later in life and have no clear familial or genetic association.