Optive Fusion drops have a unique formula that blends several ocular lubricants (sodium hyaluronate, carboxymethylcellulose & glycerine) to give enhanced 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 Plus for a different blend of lubricants. It has a unique formula to provide long lasting comfort. Firstly it lubricates the eye surface, secondly it moisturises the ocular surface cells by restoring the osmotic balance. 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.