Viscohyal is a prescription drug used in ophthalmology and ENT. The main ingredient of the drug is Sodium Hyaluronate, 1mg/ml, packaged in a 5ml bottle of eye drops. Eye drops treat keratoconjunctival epithelial disorders caused by dry eyes, Sjogren's syndrome, Steven-Johnson syndrome... So how to use Viscohyal effectively and limit the unwanted effects of the drug?