Objective of pharmacologic vitreolysis.

The goal of pharmacologic vitreolysis is to cleave the vitreoretinal junction, thereby inducing posterior vitreous detachment (PVD), and to liquefy the vitreous gel. There are several reasons to pursue a pharmacologic approach: (1) Mechanical vitrectomy is incomplete. Both at the posterior pole and in the retinal periphery, remnants of the cortical vitreous are left behind at the internal limiting membrane of the retina, causing vitreoretinal traction and (re)proliferation of cells, and leading to surgical failure. (2) Pharmacologic vitreolysis offers complete PVD without mechanical manipulation at the vitreoretinal interface, such as ILM peeling, thereby minimizing the risk of iatrogenic damage to the macula. (3) An intravitreal injection resulting in complete PVD is a less traumatic approach than vitrectomy, and it might be beneficial as prophylactic treatment regime in retinal diseases characterized by fibrocellular and fibrovascular proliferation at the vitreoretinal interface, such as diabetic macular edema and proliferative retinopathy, in order to prevent advanced stages of disease. (4) Cleaving the cortical hyaloid completely from the retina changes the molecular flux across the vitreoretinal interface and improves oxygen supply to the retina, a major mechanism of action which might significantly interfere with biochemical pathways of retinal hypoxia, leading to an overexpression of vasoactive substances such as vascular endothelial growth factor.