[The effect of the corneal epithelium on the biosynthesis of keratin sulphate in the stroma with regard to curvature variations important for wearing contact lenses (author's transl)].

Intact or denuded bovine corneas were incubated in the presence of 14lC GlcN and parts of the proteoglycan-glycoprotein complexes of the stroma were extracted by 0.15M NaCl and successively by 1.0M CaCl2. The specific activities of total GAG and KS were determined. In the presence of the epithelial layer the biosynthesis of total GAG and KS was found to be significant higher compared to denuded corneas when light influence was excluded during the incubation. The GAG and especially KS play a role in the regulation of the dehydratation of the corneal stroma. In the young myope dehydratation and flattening of corneas after contact lens wear is reported by several authors. It may be suggested that suppression of the activating effect of the epithelium on the KS biosynthesis in the central part of the cornea is involved in the changes of corneal curvature after prolonged wearing of hard contact lenses. Since visible light decreases the activating effect of the epithelium in our experiments it may be suggested that the wearing of dark coloured glasses my be contraindicated in the young myope who wears hard contact lenses.