Hypromellose, short for hydroxypropyl methylcellulose (HPMC), is a semisynthetic, inert, viscoelastic polymer used as an ophthalmic lubricant found in a variety of commercial products.Hypromellose solutions were patented as a semisynthetic substitute for tear-film. Its molecular structure is predicated upon a base celluloid compound that is highly water soluble. Post-application, celluloid attributes of good water solubility reportedly aids in visual clarity. When applied, a hypromellose solution acts to reduce the friction or viscosity of the eyes' existing natural environment, thereby expanding the thickness of the tear-film. Hypromellose augmentation therefore results in extended lubricant time presence on the cornea, which theoretically results in decreased eye irritation, especially in dry climates, home, or work environments.OTC in a variety of products, Hypromellose 2% solution has been documented to be used during surgery to aid in corneal protection and during orbital surgery.[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstract&list_uids=16052145&query_hl=8&itool=pubmed_docsum" target="_blank" >^*