Provided is a method of stimulating collagen synthesis and proteoglycan (lumican and keratocan) accumulation. Collagenase isolated keratocytes were cultured with or without insulin with or without ascorbate. Insulin stimulates the synthesis of collagen but does not affect the accumulation of lumican and keratocan. Insulin plus ascorbate, however, stimulates the synthesis of collagen and increased the accumulation of these proteoglycans. The accumulation of PGDS, a KSPG that does not interact with collagen, is not affected by ascorbate. Only the collagen made in the presence of ascorbate was pepsin resistant. EDB overrode the effects of ascorbate on pepsin resistance and proteoglycan accumulation.