The Prognostic Utility of the Silicone Study Classification System: Silicone Study Report 9

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Abstract

Objective

To evaluate the reproducibility and the prognostic utility of the Retina Society and Silicone Study Classification Systems in eyes after surgery for severe proliferative vitreoretinopathy (PVR).

Design

Subgroup analysis of the Silicone Study--a randomized, multicentered, surgical trial.

Setting

Community and university-based ophthalmology clinics.

Materials

Three hundred forty eyes with preoperative and intraoperative evaluations using both systems of grading PVR (reproducibility study), and 287 eyes with preoperative and intraoperative evaluations using both systems of grading PVR and with a 24-month follow-up examination (prognosis study).

Interventions

Vitrectomy for PVR with long-acting perfluoropropane gas or silicone oil as the intraocular tamponade.

Outcome Measures

Retinal reattachment, visual acuity (>or=to5/200), intraocular pressure, corneal clarity, and the need for reoperation.

Results

The reproducibility of the Silicone Study Classification System was 64% (type of contraction), 77% (number of clock hours), 67% (posterior PVR), 88% (anterior and posterior PVR), and 94% (anterior, posterior, and subretinal PVR). The reproducibility of the Retina Society Classification System was 99%. Using the Silicone Study Classification System, location of PVR predicted visual acuity (P=.004, chi squared test for trend) and hypotony (P=.03, chi squared test for trend). Using the Retina Society Classification System, the grade of PVR predicted only visual acuity (P=.01, chi squared test for trend). For eyes with anterior and posterior PVR, there was a decreasing trend in successful visual acuity outcome with increasing severity of PVR (from C-3 to D-3, P=.02, chi squared test for trend).

Conclusions

Although the classification of PVR using the Silicone Study Classification System was not reproducible for the type of contraction or for posterior PVR, identification of the anteroposterior extent of the PVR was prognostic of visual acuity and hypotony at 24 months. The joint knowledge of the location of PVR (using the Silicone Study Classification System) and the tightness of the funnel for retinas with 9 to 12 clock hours involved by fixed folds (using the Retina Society Classification System) has prognostic utility for eyes with anterior and posterior PVR.

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