Abstract
Purpose: :
To investigate whether intraocular levels of vascular endothelial growth factor (VEGF) differ in patients with diffuse vs focal diabetic macular edema (DME).
Methods: :
Prospective cohort study of patients with DME (clinically significant or not) were recruited. Exclusion criteria included age <18 years and any history of: ocular surgery, uveitis, non-diabetic macular edema, age-related macular degeneration, branch or central retinal vein or artery occlusion, juxtafoveal retinal telangictasia or any other condition that could explain the macular edema. Patients were also excluded if they had laser, steroid or anti-VEGF treatments within 4 months of enrollment. Patients were explained the risks and benefits to enrolling in the study prior to signing the informed consent. All patients underwent biomicrosopic exam and imaging with fundus photography, fluorescein angiography, and optical coherence tomography using Heidelberg Spectralis HRA+OCT (Heidelberg, Germany) to classify the macular edema into focal or diffuse. The severity of retinopathy was graded using the Early Treatment Diabetic Retinopathy Study (ETDRS) scale. Anterior chamber aqueous samples were collected February through November 2009 by a paracentesis using sterile technique. The samples were immediately frozen to -80oC and the VEGF levels were measured by enzyme-linked immunosorbent assay (Calbiochem, La Jolla, CA).
Results: :
17 eyes: 10 with focal DME (6 men, 4 women) and 7 with diffuse DME (4 men, 3 women). Mean age of the focal and diffuse DME patients were 56.9±8.4 and 54.6±13.5 years old, respectively. There was no statistically significant age difference between the two groups (p=.70). 8 eyes had moderate non-proliferative diabetic retinopathy (NPDR) (7 focal group, 1 diffuse group), 4 eyes with severe NPDR (2 focal group, 2 diffuse group) and 5 eyes with proliferative diabetic retinopathy (1 focal group, 4 diffuse group). Focal photocoagulation had been performed in 3 eyes (2 focal group, 1 diffuse group) and scatter photocoagulation in 5 eyes (1 focal group, 4 diffuse group) prior to recruitment. Aqueous levels of VEGF were higher in diffuse DME (341.6 pg/ml ± 200.8) than in focal DME (186.8 pg/ml ± 101.2), p=.048.
Conclusions: :
We found a statistically significant difference in aqueous VEGF levels higher in diffuse DME than in focal DME. These findings may alter therapeutic decision making when treating DME. Larger, randomized control studies are still needed to definitively answer this question.
Keywords: diabetic retinopathy • edema • vascular endothelial growth factor