Conditions: Diabetic Macular Edema
Keywords: diabetic retinopathy macular edema intravitreal Avastin/ Triamcinolone / Lucentis
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 71
Healthy volunteers: no

Brief summary:
The purpose of this study is to investigate the change in macular edema and the absolute change in visual acuity following intravitreal administered injections of Bevacizumab (Avastin®) or Ranibizumab (Lucentis®) compared with Triamcinolone (Volon A®) in patients with clinical significant diabetic macular edema.

The investigators monitor the change in macular edema measured with standard optical coherence tomography (OCT) and the absolute change in visual acuity analyzed by standardized charts according to the protocol used in the Early Retreatment in Diabetic Retinopathy Study (ETDRS).

Detailed description:
Diabetes mellitus is the most common endocrine disease in developed countries, with prevalence estimates ranging between 2 to 5% of the world's population. Diabetic retinopathy and diabetic macular edema are common microvascular complications in diabetic patients and may lead to decreasing of visual acuity, eventually to blindness. The Wisconsin Epidemiologic Study found an incidence of macular edema of 20.1% in the younger-onset group and of 14 to 25% in patients with type 2 diabetes mellitus over a period of 10 years.

Diabetic macular edema is characterized by the accumulation of extracellular fluid in Henle´s layer and the inner nuclear layer of the retina. There pathogenesis involves the interaction of several factors: the breakdown of the blood-retinal-barriers, production of biochemical factors, tissue hypoxia, retinal circulatory changes and vitreous tractions.

Laser photocoagulation is the most common treatment modality for diabetic macular edema. Perifoveal focal/grid laser coagulation was found to be effective saving the visual acuity in only 50% of patients with diabetic macular edema and just 3-14% of treated patients had an improved visual acuity post-operatively. The decent results of laser coagulation are associated with potential side effects as paracentral scotomas\[4\], change of color discrimination, development of epiretinal gliosis and subretinal fibrosis and expansion of laser scar size.

In the past few years, several studies investigating the effect of intravitreal steroids such as triamcinolone in patients with diabetic macular edema found a significant reduction in macular edema. Therefore intravitreal steroids have become part of standard therapy in the treatment of diabetic macular edema.

Furthermore, some studies showed that the vascular endothelial growth factor (VEGF) is the major angiogenic stimulus responsible for increase of vasopermeability, cell proliferation and angiogenesis in diabetic retinopathy (DRP). Evaluation of VEGF levels in the vitreous have indicated a role for VEGF in diabetic macular edema: vitreous samples of patients with diabetic macular edema contain elevated VEGF concentration and injection of VEGF in experimental studies led to breakdown of the blood-retina barrier.

Not only in age-related macular degeneration but also in other diseases like in diabetic macular edema we can find an increasing evidence for a therapeutic role of anti-VEGF drugs. Intravitreal injections have become the most favored treatment procedure for administering anti-VEGF drugs.

The side effects and the modest results of laser treatment on the visual acuity in diabetic macular edema led to studies using anti-VEGF therapy. Unpublished study results on the aptamer pegaptanib (Macugen®) are promising. A study using the antibody fragment Ranibizumab (Lucentis®) is in progress.

Currently there is one anti-VEGF drug already on the market: Bevacizumab (Avastin®), which has approved as intravenous infusion for the treatment of metastatic colo-rectal cancer. Previous studies have shown that systemic use of Bevacizumab (Avastin®) can obtain very promising results on patients with choroidal neovascularisation (CNV) by age-related macular degeneration. This drug, a monoclonal full-length antibody, designed to bind all isoforms of VEGF, is a large molecule. But case reports in patients with CNV caused by age-related macular degeneration and with macular edema from central retinal vein occlusion indicate that intravitreally given Bevacizumab (Avastin™) is effective in diseases originating from the choroids and also the retina. These findings imply a sufficient penetration of the retina by Bevacizumab (Avastin®).

A recent study investigating the effect of intravitreal bevacizumab (Avastin®) in patients with diabetic macular edema found a significant reduction in macular edema.

Based on these new findings and the important role of VEGF in diabetic macular edema and in proliferative diabetic retinopathy, we propose a double-masked, randomised pilot study for treatment of diabetic macular edema with intravitreally administered anti VEGF (Avastin®/Lucentis®) compared with intravitreally administered triamcinolone (VolonA®).

Arms:
arm 1: 15 patients with clinical significant macular edema receive an injection of 2,5 mg Avastin every month. After three initial injections of Avastin re-injection is performed if the central retinal thickness measured with optical coherence tomography (Stratus OCT, Zeiss) stays more than 300 microns. If the Central retinal thickness decreases under 300 microns a sham injection is performed. arm 2: 30 patients with a clinical significant diabetic macular edema receive an intraocular injection of 8mg triamcinolone at baseline under sterile conditions. 1 and 2 month after the baseline injection, patients receive a sham injection. After three month re-injection of 8mg Triamcinolone is performed if the central retinal thickness measured with optical coherence tomography (Stratus OCT, Zeiss) stays more than 300 microns. If the Central retinal thickness decreases under 300 microns patients will receive a sham injection. In between two injection of 8mg Triamcinolone must be an temporal interval of at least 3 months. arm 3: 15 patients with clinical significant macular edema receive an injection of 0,5 mg Lucentis every month. After three initial injections of Lucentis re-injection is performed if the central retinal thickness measured with optical coherence tomography (Stratus OCT, Zeiss) stays more than 300 microns. If the Central retinal thickness decreases under 300 microns a sham injection is performed.

Interventions: intervention 1: Bevacizumab (Avastin) intervention 2: Triamcinolone intervention 3: Sham intervention 4: Lucentis
Intervention descriptions: intervention 1: The intravitreal injection of Bevacizumab (Avastin®) is performed in the operating room under sterile conditions. The patient receives an initial drop of lidocaine 4% into the study eye followed by betaisodona solution. Then the lid margins, the lids and the periocular skin are washed carefully with betaisodona. The eye is draped in a sterile fashion. A sterile lid speculum is inserted by the surgeon. Another drop of betaisodona is applied into the eye. A circle is used to mark the injection site 3.5mm from the limbus in the inferior temporal quadrant. The injection is given at the marked site, slowly, at a 90 degree angle. After injecting the total volume of 0.1ml the needle is slowly withdrawn. Another drop of betaisodona is given as well as an antibiotic/steroid ointment. intervention 2: The intravitreal injection of triamcinolone (Volon A®) is performed in the operating room under sterile conditions at baseline. The patient receives an initial drop of lidocaine 4% into the study eye followed by betaisodona solution. Then the lid margins, the lids and the periocular skin are washed carefully with betaisodona. The eye is draped in a sterile fashion. A sterile lid speculum is inserted by the surgeon. Another drop of betaisodona is applied into the eye. A circle is used to mark the injection site 3.5mm from the limbus in the inferior temporal quadrant. The injection is given at the marked site, slowly, at a 90 degree angle. After injecting the total volume of 0.1ml the needle is slowly withdrawn. Another drop of betaisodona is given as well as an antibiotic/steroid ointment. intervention 3: Patients receiving sham intravitreal injections do not receive an actual injection of study drug. The injecting physician performing the sham injection will be unmasked to the treatment to the treatment assignment regarding active versus sham. The injecting physician will perform the same pre-injection procedures for the patients receiving bevacizumab or triamcinolone, An empty syringe without a needle will be used in the sham injection. The injecting physician will mimic an intraocular injection by making contact with the conjunctiva and applying pressure without the needle. Immediately following the sham injection, the injecting physician will perform the same post-injection procedures as those performed on patients receiving bevacizumab or triamcinolone. intervention 4: The intravitreal injection of Ranibizumab (Lucentis®) is performed in the operating room under sterile conditions. The patient receives an initial drop of lidocaine 4% into the study eye followed by betaisodona solution. Then the lid margins, the lids and the periocular skin are washed carefully with betaisodona. The eye is draped in a sterile fashion. A sterile lid speculum is inserted by the surgeon. Another drop of betaisodona is applied into the eye. A circle is used to mark the injection site 3.5mm from the limbus in the inferior temporal quadrant. The injection is given at the marked site, slowly, at a 90 degree angle. After injecting the total volume of 0.05ml the needle is slowly withdrawn. Another drop of betaisodona is given as well as an antibiotic/steroid ointment.

Protocol document: