Classifications for Proliferative Vitreoretinopathy (PVR): An Analysis of Their Use in Publications over the Last 15 Years

Table 3

The updated Retina Society Classification (1991). The revised classification incorporated changes proposed by the Silicone Study Group [10] and modifications proposed also by other authors [12]. Three grades of supposed increasing severity were described, emphasizing the posterior and anterior locations of proliferation. The new classification kept grades A and B, modified grade C, and eliminated grade D. According to the Silicone Study Classification, a more detailed description of grade C (posterior and anterior) PVR was made by adding the types of contraction, the extent of which was detailed by using clock hours instead of quadrants. Modified from [11].

The updated Retina Society Classification [11]
Grade and type	Clinical signs
A	Vitreous haze, pigment clumps, and pigment clusters on inferior retina
B	Wrinkling of inner retinal surface, retinal stiffness, vessel tortuosity, rolled and irregular edge of retinal break, and decreased mobility of vitreous
CP (posterior); (i) Type: (a) Focal; (b) Diffuse; (c) Subretinal	Full-thickness retinal folds or subretinal strands posterior to equator (1–12 clock hours involvement); (i) Starfolds posterior to vitreous base; (ii) Confluent starfolds posterior to vitreous base; optic disc that may not be visible; (iii) Proliferation under the retina; annular strand near disc; linear strands; moth-eaten-appearing sheets
CA (anterior); (i) Type: (a) Circumferential; (b) Anterior	Full-thickness retinal folds or subretinal strands anterior to equator (1–12 clock hours involvement), anterior displacement, and condensed vitreous strands; (i) Retina contraction inwards at the posterior edge of the vitreous base; with central displacement of the retina; peripheral retina stretched; posterior retina in radial folds; (ii) Snterior contraction on the retina at the vitreous base; ciliary body detachment and epiciliary membrane; iris retraction