Collagen is one of the major extracellular macromolecules in almost every connective tissue, including ocular tissue, which has an abundance of collagen. The cornea of all vertebrates begins its development in the ectoderm overlying the lens. The cornea serves as a major refractive element by transmitting light to the chambers of the eye. The refractive properties of the cornea have been ascribed, in part, to the unique disposition and orientation of the collagen fibrils in the stroma. The embryonic chick eye has been most widely used to study collagen types and their distributions and roles in development, primarily because of its ready availability and the comprehensive knowledge of its morphology. The presence of each collagen type in the ocular tissues has been identified by either biochemical analysis or immunofluorescence. Immunofluorescent studies of the embryonic chick eye revealed the type one collagen to be the first and principal collagen type detected in the primary corneal stroma, followed by type II collagen.