Abstract
Purpose:
Many untreated patients with retinal vein occlusion (RVO) show a progressive increase in posterior RNP over time that is significantly reduced by inhibiting vascular endothelial growth factor (VEGF) with intraocular injections of RBZ. We sought to determine whether RBZ has the same effect in DME.
Methods:
Masked graders at an independent reading center measured the area of RNP in the center, inner, and outer central subfields of fluorescein angiograms obtained at baseline (n=666) and months 3, 6, 12, 18, 24, 30, and 36 in DME patients in the RISE and RIDE trials. Observed data was used (no imputation) and percentages were compared using the chi-square test.
Results:
There was a progressive increase in the percentage of control DME patients (monthly sham injections for 24 months with most crossing over to monthly 0.5 mg RBZ at month 25) that showed an increase from baseline in posterior RNP at month 3 (18.5%) and beyond with a peak of 37.6% at month 24, followed by a plateau or slight decrease at months 30 and 36 when most received RBZ 0.5 mg. Compared to the control group, the 0.5mg RBZ group showed a significantly smaller percentage of patients with an increase from baseline in posterior RNP at month 3 (9.6 versus 18.5, P=0.016), month 36 (18.4 versus 31.6, P=0.0095), and all time points in between; percentages were significantly less than the control group for the 0.3 mg RBZ group at month 3 (13.4%), month 36 (22.8%) and all but 2 other time points. The percentage of patients that showed an increase in RNP from 0 at baseline was 10.4 (control) versus 3.6 (0.5 mg RBZ, P=0.025) at month 3 and the difference was maintained at all time points (26.0 versus 13.8, P=0.023 at month 36); significant reductions were also seen in the 0.3 mg RBZ group compared with control at all time points beyond month 3.
Conclusions:
Roughly 1/3 of control DME patients show an increase in posterior RNP over a 2-3 year period, and this is substantially reduced by monthly injections of 0.5 mg or 0.3 mg of RBZ. Thus similar to the situation in patients with RVO, blockade of VEGF reduces progression of RNP in patients with DME, indicating that regardless of the underlying retinal vascular disease process, high levels of VEGF are associated with closure of retinal vessels which is prevented by neutralization of VEGF with injections of RBZ.
Keywords: 499 diabetic retinopathy •
700 retinal neovascularization •
748 vascular endothelial growth factor