Optive Plus drops have a unique formula that offers lubrication and protection to the cornea for long-lasting relief from moderate to severe dry eye symptoms. Use Optive for less severe symptoms, or consider Optive Fusion for a different blend of lubricants. It has a unique triple action formula to provide long-lasting comfort. Firstly it lubricates the eye surface, secondly it moisturises the ocular surface cells by restoring the osmotic balance and finally it protects the natural tears with a lipid enhancement. The multi-use bottle can be kept for 6 months after opening as it has a gentle preservative in called Purite, which breaks down in the eye as natural tear components.