[The predictive value of a classification for proliferative diabetic vitreoretinopathy]

Kroll's classification of proliferative diabetic vitreoretinopathy (PDVR) defines stage A (vitreoretinal proliferations without retinal detachment), stage B (partially detached retina not involving the macula), stage C (partially detached macula) and stage D (completely detached macula). The purpose of this study was to analyse the prognostic value of Kroll's classification in respect of the postoperative results of vitreoretinal surgery based on our group of patients.

The charts of 563 patients who underwent vitrectomy because of PDVR between 1990 and 1997 were examined retrospectively. Postoperative visual acuity, possible risk factors, frequencies of silicone oil tamponade and revitrectomies were related to the preoperative staging of PDVR. The influence of possible predictive factors on the postoperative visual outcome were evaluated using multivariate logistic regression analysis.

After vitreoretinal surgery mean postoperative visual acuity was significantly better in stage A compared to stage C (p < 0.01) or D (p < 0.0001). In 179 out of 563 eyes (31.7 %) revitrectomy (including silicone oil removal) was required and in 51 eyes (9.1 %) more than one revitrectomy was performed. Silicone oil tamponade was used in 22 out of 253 eyes (8.7 %) classified as stage A, in 27 out of 201 eyes (13.4 %) of stage B, in 17 out of 78 eyes (21.8 %) of stage C and in 10 of 31 eyes (32.3 %) of stage D. Postoperative increase of visual acuity of more than 3 lines was significantly less frequent in stage B (p < 0.014), C (p < 0.039) and D (p < 0.001) compared to stage A.

Kroll's classification for PDVR has a high prognostic value for the postoperative visual outcome and level of surgical risk management. Thus patients with good prognosis can be identified easily, facilitating the decision for surgery.