Historically, prior to the advent of OVDs, it was commonplace and expected, to have at least transient corneal edema after intraocular surgery, but the relationship to endothelial cell damage was only well worked out in the 1960s and 1970s. The advent of intraocular lenses (IOLs) brought the issue to the fore when it was discovered that polymethylmethacrylate (PMMA), the original material (Perspex™ CQ) from which Rayner made Ridley’s first IOLs and from which all IOLs were initially manufactured, was destructive of endothelial cell membranes upon contact, resulting in an explosion in demand for corneal transplantation as IOLs became more commonly implanted. Initially, endothelial cell protection during IOL implantation was achieved with an air bubble or the patient’s own serum. This was clearly suboptimal as a long-term solution. Commercial OVDs, which first appeared in 1980, and viscosurgery, evolved as the answer to achieve corneal protection while facilitating surgery by creating and maintaining intraocular surgical space. This chapter reviews the history of OVDs and the science of OVD development and usage techniques which have made them universally adopted surgical adjuncts in cataract surgery and other intraocular procedures.