Session Title: Vascular Diseases and Diabetic Retinopathy II
Session Date/Time: Friday 18/09/2015 | 16:30-18:00
Paper Time: 17:18
First Author: : L.Nicholson UNITED KINGDOM
Co Author(s): : N. Patrao J. Ramu C. VazquezAlfageme M. Muwas P. Hykin S. Sivaprasad
PURPOSE:The current standard of treatment for centre-involving diabetic macular edema (DME) is intravitreal ranibizumab therapy. Ranibizumab inhibits endogenous vascular endothelial growth factors (VEGF) and consequently decreases vascular permeability. Several cytokines contribute to the pathogenesis of DME but VEGF is thought to be the prime stimulus. Intraocular VEGF levels increases with the severity of diabetic retinopathy (DR) and VEGF levels are highest in eyes with proliferative diabetic retinopathy (PDR). Therefore, we hypothesized that as the response of DME to ranibizumab is by suppression of VEGF, the initial response of DME should vary with severity of DR.
This retrospective study was performed in the NIHR Biomedical Research Centre, Moorfields Eye Hospital and University College London, UK. Local institutional review board approval was obtained and the study was conducted in accordance to the tenets of the Declaration of Helsinki.
Consecutive patients with centre-involving DME defined as central subfield thickness (CSFT) of more than 300microns who were initiated on ranibizumab therapy and had 3 consecutive monthly ranibizumab therapy from June 2013 to October 2014 in Moorfields Eye Hospital, London were included. Bilateral cases if eligible were included and each eye studied separately. Exclusion criteria included vitrectomised eyes, cataract surgery or treatment of DME with any other agents in the previous three months or laser from the previous four months to last follow-up visit. CSFT measurements were taken from SD-OCT imaging of the macula using Topcon 3D OCT-2000. Retinopathy status classified as mild non-proliferative DR (R1) , moderate to severe NPDR (R2) and PDR (R3). Presence of prior panretinal photocoagulation (PRP) for PDR at baseline was recorded.
Data on 258 patients on ranibizumab therapy were included in this study. The mean age of patients was 64.5 years with a male to female ratio of 1:1.6. The baseline DR status were 29.62% R1, 32.69% R2 and 36.92% R3. Mean baseline CSFT for all eyes was 460.04±108.9µm. Baseline CSFT for R1, R2 and R3 respectively were 438.8±90.2µm, 475.6±109.0µm and 464.6±120.7µm with no significant difference between them (p=0.144). Mean change in CSFT after three consecutive injections was 129.3±117.3µm. For individual retinopathy status, the mean changes were 97.9µm for R1, 140.5µm for R2 and 145.4µm for R3. The changes in CSFT between groups were statistically significant (p=0.023). Mean baseline CSFT for eyes with evidence of previous PRP was 463.35±120.40µm and this was compared to PRP naïve R2 eyes which had a mean CSFT of 478.84±109.72µm. The difference was not significant, p=0.21. The mean change in CSFT between these two groups were not significant, 141.13µ and 145.91µm respectively (p=0.82).
The initial anatomical response of DME to a course of three intravitreal ranibizumab injections was more significant in the PDR group despite previous treatment with PRP suggesting that intraocular VEGF levels remains elevated despite PRP treatment.