The vitreous gel is a transparent, hypocellular tissue that effectively transmits light with negligible scatter or energy absorption. Although it is relatively resilient to age-related wear and tear, the vitreous is susceptible to injury from inflammatory cells and substances that breech the blood-retinal barrier. Over the course of a lifetime, the vitreous undergoes a variety of poorly understood, degenerative changes that lead to liquefaction—also referred to as syneresis. Vitreous syneresis is the most common predisposing factor for posterior vitreous detachment, which places a patient at risk for retinal detachment. While vision-threatening complications from deposits within the vitreous are uncommon (e.g., amyloid), the formation of vitreous membranes inflict considerable ocular morbidity. Vitreous membranes are a manifestation of a heterogeneous collection of disorders that share a final common pathway. Proliferative vitreoretinopathy (PVR) is the term applied to the uncontrolled growth of fibroglial membranes associated with rhegmatogenous retinal detachments. The most common reason for failed retinal reattachment surgery, PVR appears to exhibit an exaggerated reparative response to injury.