Proliferative Vitreoretinopathy (PVR) is an eye condition characterized by the abnormal formation of scar tissue within the eye. This scarring can significantly impact vision, often leading to severe visual impairment or even blindness. PVR is a complex healing response that develops as a complication of certain eye events.
Understanding PVR and Its Impact on Vision
PVR involves the growth and contraction of cellular membranes within the vitreous cavity and on the retinal surface. The vitreous is the clear gel-like substance that fills the space behind the eye’s lens and in front of the retina. These scar tissue membranes can form on either side of the retina—epiretinal (on the surface) or subretinal (underneath). The formation of these membranes pulls on the retina, causing it to wrinkle, fold, and ultimately detach from the back of the eye.
The traction leads to fixed retinal folds, potentially transforming a rhegmatogenous retinal detachment into a tractional detachment. Scarring within the retina (intraretinal fibrosis) can also prevent it from flattening even after scar tissue removal. Patients experiencing PVR may notice symptoms such as blurry or distorted vision, new or persistent floaters, and flashes of light. As the condition progresses, a shadow or curtain may appear in the visual field, indicating a more widespread retinal detachment.
Why PVR Develops
PVR most commonly develops as a complication following a rhegmatogenous retinal detachment (RRD). While initial retinal reattachment surgery for RRD is successful in about 90% of cases, PVR occurs in 5% to 10% of these patients. PVR can also arise after severe eye trauma, such as an open globe injury, with up to 50% of these cases developing the condition.
The formation of scar tissue in PVR is an abnormal wound-healing process in response to tissue damage and inflammation within the eye. When the retina detaches, cells like retinal pigment epithelial (RPE) cells and glial cells are activated and begin to multiply and migrate. These cells then lay down extracellular matrix components, forming contractile membranes. Risk factors include large or multiple retinal tears, vitreous hemorrhage (bleeding in the eye), and prolonged retinal detachment before surgical treatment. Inflammation within the eye, prior eye surgeries, and cigarette smoking also contribute to PVR development.
Treatment Approaches for PVR
The main treatment for PVR is surgical intervention, specifically pars plana vitrectomy. During a vitrectomy, small instruments are inserted through tiny incisions to remove the vitreous gel. This allows the surgeon to access and carefully peel away the scar tissue membranes from the retinal surface.
The goal of this surgery is to release the traction on the retina and allow it to reattach. In some instances, a scleral buckle, a silicone band placed around the outside of the eye, may be used to provide external support and help flatten the retina. Following scar tissue removal, the eye is often filled with a temporary substitute to hold the retina in place as it heals. Options include a gas bubble (e.g., sulfur hexafluoride or perfluoropropane), which gradually absorbs, or silicone oil, used for more complex cases or longer-term support. Silicone oil requires a second surgery for removal, usually after several months.
Outlook After PVR Treatment
Treating PVR is a complex process, and the visual outcome can vary significantly. While surgical reattachment rates for PVR are often high, ranging from 45% to 85%, achieving good visual function is more challenging. Vision recovery depends on factors like the severity of the PVR, the duration of retinal detachment, and whether the central part of the retina (macula) was affected.
Complete vision restoration is not always possible due to permanent damage to the retinal cells. Patients may experience some degree of blurred or distorted vision even after successful anatomical reattachment. Recurrence of retinal detachment due to new scar tissue formation is a concern, and requires close post-operative monitoring. In some cases, multiple surgeries may be required to manage recurrent detachments.