Biotrue Hydration Plus Contact Lens Solution, 16 Fluid Ounce (Pack of 2) Biotrue Hydration Plus is now enhanced to keep even more moisture on your contacts (for 12 hours compared to Biotrue Multi-Purpose Solution, based on a laboratory study). It contains naturally inspired ingredients, inspired by the biology of the eye: its enhanced with 25% more hyaluronan (a.k.a. HA, a moisturizer found naturally in tears) vs. Biotrue Multi-Purpose Solution; and is the only contact solution to contain an antioxidant (protects HA against free radicals) as well as potassium (an electrolyte found naturally in tears). Biotrue Hydration Plus also matches the pH of healthy tears to help make contacts comfortable when you put them in.