Mucus in the healthy and diseased eye.

Mucous glycoproteins play an important role in maintaining the normal surface of the eye. Changes in the physical properties and chemical composition occur in disease with increased viscosity and a shift in the type of acid glycoprotein towards a predominance of sulphomucin causing some of the distinctive clinical features seen in dry eyes, superior limbic keratitis (SLK), vernal catarrh, and neuroparalytic keratitis.