Retina Today - Surgical Updates: Current Management of Giant Retinal Tears With Proliferative Vitreoretinopathy (May/June 2011)

摘要

Proliferative vitreoretinopathy (PVR) is a late complication of vitreoretinal surgery and is the leading cause of failure of primary surgery. The clinical presentation of PVR involves fibrocellular membranes proliferating on both surfaces of the retina and anteriorly at the vitreous base. However, when a giant retinal tear is concurrently present, diffuse proliferation is more likely to result in a closed-funnel configuration because retinal contraction is unrestrained after the flap tears along the posterior margin of the vitreous base. Several associated clinical findings in giant retinal tears can predispose to the development of PVR. The extensive dispersion of pigment in the vitreous and on the retinal surface suggests the migration of retinal pigment epithelial (RPE) cells, which can increase the potential for the development of PVR. Before the use of perfluorocarbon liquids, giant retinal tears were managed using an expanding gas bubble and scleral buckling, or with vitrectomy and fluid-gas exchange with the patient prone. The repositioning of the posterior flap of the giant tear was unpredictable. Thus, the potential for a higher rate of PVR was increased; in one large series,1 PVR developed in 58% of eyes. Even in the era of perfluorocarbon liquids, the incidence of PVR is higher than that following conventional retinal detachment surgery.2 In most recent series, the rate of PVR ranges between 12% and 15% of eyes.3,4 The reasons for this higher rate of occurrence are unclear, but several factors may contribute to a greater propensity to develop periretinal proliferation in giant retinal tears. Patients with giant retinal tears tend to be younger. A giant retinal tear exposes a large area of bare RPE cells that can migrate from the subretinal space through the large retinal opening into the vitreous. The increased access of exposed RPE cells allows greater dispersion of the cells into the vitreous, potentially increasing the risk of proliferation.5 A greater amount of thermal treatment (cryotherapy or photocoagulation) is required to treat a large retinal break, resulting in a greater breakdown of the blood-retinal barrier. Thus, although high rates of final retinal reattachment are achieved in giant retinal tears (greater than 95%), there is still a higher rate of reoperation compared to routine rhegmatogenous retinal detachments to achieve this final rate. SCLERAL BUCKLING FOR PVR IN GIANR RETINAL TEAR DETACHMENT Although the role of scleral buckling is controversial in the management of giant retinal tears without PVR, I advocate the use of scleral buckling in giant retinal tears with PVR. The role of the scleral buckle is to relieve the residual tractional forces along the vitreous base and to reduce any circumferential traction caused by the PVR process. The scleral buckle should be placed to support the vitreous base in the area where the retina is not torn. The scleral buckle does not need to support the posterior edge of the giant tear because no vitreous traction is present. Generally, I prefer using a Type 42 band with a low-lying placement as the first step in the surgery. The height of the buckle should be adjusted for a low, broad elevation. The band should be tightened so that the posterior slope of the buckle can still be visualized, facilitating the application of endophotocoagulation during surgery or, when necessary, postoperative laser photocoagulation along the posterior slope of the buckle. A high scleral buckle is not desirable, as it may result in radial folds because of the reduced circumference of the globe; this should be avoided. SMALL-GAUGE VITRECTOMY IN PVR ASSOCIATED WITH GIANT RETINAL TEAR DETACHMENT Recent advances in small-gauge vitreoretinal surgical systems have greatly expanded the surgical indications for 23- gauge and 25-gauge surgery. Prior to these improvements (improved fluidics, improved stiffness