Collagen types in keratoconus.

Collagen types in normal human and keratoconus corneas were separated by salt fractionation and thermal gelation in the pepsin-soluble fraction of the lyophilized tissues. Peptic digestion indicated no significant differences between normal and keratoconus corneas. Further collagen characterization was performed using SDS-PAGE. Collagen concentration were determined via hydroxyproline. Soluble collagens from normal human cornea represent 85% collagen type I, maximally 10% collagen type III and 5% collagen type V. Soluble collagens of keratoconus corneas consist of 90% type I collagen and maximally 5% type II and type V collagen.