Oftentimes, corneal damage from ill-fitting contact lenses or disease conditions will result in swelling (edema). Normally the cornea is in an isotonic state; however, when edema is present, the cornea is in a hypotonic state so that when a hypertonic solution is introduced into the eye, a state of equilibrium is created, thus providing comfort. The ointment is for night-time use. Active Ingredient: Sodium Chloride 5.0%.