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Amar J. Patel, Kenny Downes, Alex Davis, Arup Das; Are Proliferative Diabetic Retinopathy and Diabetic Macular Edema two different disease processes? A Retrospective Cross-sectional Study. Invest. Ophthalmol. Vis. Sci. 2012;53(14):377.
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To evaluate whether diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR) could represent two distinct clinical-pathological entities, or occur concurrently along the same spectrum of disease.
The study is a retrospective cross sectional review of patients presenting with PDR associated vitreous hemorrhage that were treated with either pan-retinal photocoagulation (PRP), or pars plana vitrectomy (PPV) with endolaser. The presence or absence of macular edema was reviewed within 3-6 months of patient presentation with vitreous hemorrhage in order to allow for a clear assessment of the macular status post intervention. The stereoscopic biomicroscopic fundus examination was completed with the OCT exam (central retinal thickness > 250 um) to grade diabetic macular edema. An analysis was done to examine the relationship of DME with risk factors like HbA1C, lipid panel, and systolic blood pressure.
A total of 263 patients were identified with active PDR associated vitreous hemorrhage over the last six years with 124 undergoing PRP in clinic and 139 undergoing PPV with endolaser. Patients who had undergone recent PRP within the last 6 months were excluded. Of the 124 patients who underwent PRP in clinic, the incidence of concurrent macular edema was 28%. Of the 139 patients who underwent PPV with endolaser, the incidence of concurrent macular edema was 13%. The results show 53 of the patients (20%) had diabetic macular edema and active PDR concurrently. The majority (80%) of patients with active PDR did not have exudative changes like CSME, indicating that PDR may be a different disease process.
This data showed that the majority of diabetic patients with active retinal neovascularization (PDR) had little or no exudative changes in the macula. In spite of the high VEGF levels expected in these patients, there was absence of macular edema in the majority of patients. It is possible that patients with diabetes go through phases of non-proliferative diabetic retinopathy, and then follow either of two clinical pathways: predominantly exudative process (DME), or predominatly proliferative process (PDR). These findings indicate that PDR and DME could be two different disease processes driven by different molecular mediators or genetic factors.
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