1. Vitrectomy and silicone oil infusion in severe diabetic retinopathy. Alessandro Castellarin, MD Ruben Grigorian, MD Neelakshi Bhagat, MD Lucian DelPriore, MD, PhD Christopher Seery, MD Marco Zarbin, MD, PhD

2. Purpose To determine the results of pars plana vitrectomy (PPV) and silicone oil infusion (SOI) in severe proliferative diabetic retinopathy (PDR).

3. Methods The records of 22 eyes (18 patients) with PDR who had undergone PPV and SOI were reviewed retrospectively. Average follow-up was 5.2 months (range 1-18 months). In 10 eyes (46%), SOI was part of the initial operation; in 12 eyes (54%), SOI was performed after previous failed PPV. A complexity score (range: 1 – 7) was defined to grade the complexity of membrane dissection.

4. Complexity score The number of quadrants of fibrovascular proliferation (FVP, 1-4 quadrants, each quadrant involved corresponds to 1 point increase in the CS). The location of FVP: anterior to the equator (0 points), posterior to the equator (0 points), both anterior and posterior (1 point). Tractional retinal detachment (TRD, 1 point). Traction-rhegmatogenous retinal detachment (TRRD, 2 points). The presence or absence of a posterior vitreous detachment (no PVD, 1 point).

5. Demographics Age 53.6 (Range 21-82) Demographics Age 53.6 (Range 21-82)

6. Surgical indications

7. Cases per complexity score

8. In 10 eyes (46%), SOI was part of the initial operation. In 12 eyes (54%), SOI was performed after previous failed PPV.

9. Rubeosis iridis (RI) was present preoperatively in 4 eyes, 2 of which had NVG. Preoperatively 14 patients were phakic, 6 pseudophakic and 2 aphakic. Eight of 14 phakic eyes underwent lensectomy (5 were left aphakic). 3 of the pseudophakic eyes were left aphakic.

10. Anatomic Outcomes Anatomic success of the study was defined as a complete attachment of the retina posterior to the equator or to the scleral buckle, if present.

11. Anatomic Outcomes

12. Postoperative Visual Acuity

13. Postoperative Rubeosis iridis (RI) was present preoperatively in 4 eyes, 2 of which had NVG. Postoperatively, 3 of 4 eyes had regressed RI. No eye had postoperative NVG. Only one eye developed RI postoperatively. SO was removed in 2 eyes (9%), at 5 months and 8 months respectively, without complication.

14. Postoperative complications

15. In a previous study to compare whether membrane viscodissection results in fewer iatrogenic breaks than pick & scissors dissection we reviewed 150 eyes that underwent vitrectomy and membrane peeling. Reattachment rate (> 6 mos. follow-up): Viscodissection (V): 30/36 (84%), No Viscodissection (NV): 38/42 (90%). Average complexity score 3.5. In the SO study the reattachment rate was lower but the case complexity was significantly grater (4.5) than the previous study (P<0.0058).

16. Conclusions SO tamponade is a useful option in severely diseased eyes with PDR, even in the presence of RI and NVG or the fibrinoid syndrome. Retinal attachment was achieved in almost 70% of cases. The majority of patients had stable or improved VA. The use of SO in severely diseased eyes with PDR may be of benefit, especially in the presence of RI. Further study with a prospective study design and larger sample size may be needed to explore this issue further.

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