Avastin prior to vitrectomy for diabetic retinopathy Intravitreal Avastin (bevacizumab, IVB) injection as an adjunct to vitrectomy in the management of severe proliferative diabetic retinopathy (PDR) improves the anatomical and functional outcomes of surgery, according to a new study.

Diabetic retinopathy is the result of microvascular retinal changes. Hyperglycemia-induced pericyte death and thickening of the basement membrane lead to incompetence of the vascular walls. As the disease progresses, diabetic retinopathy enters an advanced, or proliferative, stage. The lack of oxygen in the retina causes fragile new blood vessels to grow along the retina and in the clear, gel-like vitreous humour that fills the inside of the eye. Without timely treatment, these new blood vessels can bleed, cloud vision, and destroy the retina. Fibrovascular proliferation can also cause tractional retinal detachment. There are three major treatments for diabetic retinopathy: laser photocoagulation, injection of triamcinolone into the eye and vitrectomy. The traditional treatment for proliferative diabetic retinopathy is pan-retinal photocoagulation, which involves extrensive laser photocoagulation to large areas of the retina. In severe cases of proliferative diabetic retinopathy, when there has been extensive blood vessel growth and hemmorage in the vitreous, pan-retinal photocoagulation may be augmented by vitrectomy - the surgical removal of the vitreous from the eye. Recently, there has been reports that steroids and anti-VEGF therapy are benefitial in patients with proliferative diabetic retinopathy.

This randomized controlled trial was performed on 72 eyes of 68 patients affected by vitreous haemorrhage (VH) and tractional retinal detachment (TRD), which occurred as a consequence of active proliferative diabetic retinopathy (PDR). Patients were randomly assigned in a 1: 1: 1 ratio to receive a sham injection or an intravitreal injection of 1.25 mg of Avastin, either 7 or 20 days before the vitrectomy. In order to obtain three homogeneous groups of surgical complexity, we assigned to the following preoperative parameters a score from 0 to 3: a) vitreous haemorrhage, b) prior retinal laser-photocoagulation, c) morphological types of retinal detachment such as focal, hammock, central diffuse, table-top. Complete ophthalmic examinations and color fundus photography were performed at baseline and 1, 6, 12, and 24 weeks after the surgery.

Group A (sham injection): intraoperative bleeding occurred in 19 cases (79.1%), the use of endodiathermy was necessary in 13 patients (54.1%), relaxing retinotomy was performed on one patient (4.1%), and in four cases (16.6%) iatrogenic retinal breaks occurred. The surgical mean time was 84 minutes.

Group B (Avastin administered 7 days before vitrectomy): intraoperative bleeding occurred in two cases (8.3%) and the use of endodiathermy was necessary in two patients (8.3%). No iatrogenic breaks occurred during the surgery. The surgical mean time was 65 minutes.

Group C (Avastin administered 20 days before vitrectomy): intraoperative bleeding occurred in three cases (12.5%), the use of endodiathermy was necessary in three patients (1.5%), and an iatrogenic break occurred in one patient (4.1%) while the delamination of fibrovascular tissue was being performed. The surgical mean time was 69 minutes.

The average difference in the surgical time was statistically significant between group A and group B (p = 0.025), and between group A and group C (p = 0.031). At the end of the surgery, the retina was completely attached in all eyes. At the 6-month follow-up, we observed the development of tractional retinal detachment (TRD) in one out of 24 patients from group C (4%).

The investigators conclude that a preoperative intravitreal injection of Avastin may represent a new strategy for the surgical treatment of severe PDR by reducing retinal and iris neovascularization. This would make surgery much easier and safer, thus improving the anatomical and functional prognosis. According to this study, the best surgical results are achieved performing the IVB 7 days preoperatively.

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Graefes Arch Clin Exp Ophthalmol. 2010 Feb 5. [Epub ahead of print]