VI.G. Pharmacologic Vitreolysis with Purified Dispase (Vitreolysin™)

Vitreolysin™ is a purified 35.9 kDa extracellular neutral protease produced by Paenibacillus polymyxa. It can selectively cleave the attachment of the posterior vitreous cortex from the inner limiting membrane (ILM) due to its high affinity for type IV collagen and fibronectin, which contributes to the attachment between these two structures [see chapter II.E. Vitreo-retinal interface and inner limiting membrane]. The low affinity of Vitreolysin™ for vitreous type II collagen allows it to induce a posterior vitreous detachment (PVD) without disrupting the delicate macromolecular structure of the vitreous (Figure VI.G-1). This direct enzymatic action on the posterior vitreous cortex-ILM interface prevents vitreous liquefaction and resultant vitreoretinal traction which is a common way of PVD induction for many indirectly acting enzymes [1]. There are several other advantages of Vitreolysin™, such as lack of a known natural inhibitor, which insures reliable enzymatic activity even in complex vitreoretinal diseases where several enzyme inhibitors within the serum may leak into the eye. Vitreolysin™’s activity can be quenched by its own titratable autolysis, which ensures a fine control on its degradation and removal. Vitreolysin™ is a highly stable molecule with a long shelf life in lyophilized form. Early preclinical studies also revealed high rates (80–100 %) of PVD induction at picomolar concentrations.