Concentration gradient of vascular endothelial growth factor in the vitreous of eyes with diabetic macular edema

Vascular endothelial growth factor (VEGF) concentrations in various regions of the vitreous were examined in patients with diabetic macular edema (DME) to explore the possibility of a concentration gradient in the vitreous.

Vitreous samples were collected during vitrectomy from 71 eyes of 71 patients with DME and without posterior vitreous detachment who had not undergone panretinal photocoagulation. Vitreous samples were collected from the premacular vitreous and mid-vitreous (group A, 35 eyes), and from the premacular vitreous and peripheral cortical vitreous (group B, 36 eyes). Mean foveal thickness was measured by optical coherence tomography (OCT). Ten eyes of 10 patients with stage 3 macular hole (MH) served as controls. Vitreous VEGF levels were measured by enzyme-linked immunosorbent assay.

The VEGF concentration (mean +/- SD; pg/mL) was significantly higher in the premacular vitreous (1386.2 +/- 2134.1) than in the peripheral cortical vitreous (1169.7 +/- 1840.3; P = 0.0216) and mid-vitreous (1080.9 +/- 1534.1; P = 0.0017). The mean foveal thickness measured on OCT correlated significantly with VEGF concentrations in the premacular vitreous, peripheral cortical vitreous, and mid-vitreous (R > 0.62, P < 0.0001, for all). In controls, VEGF concentrations in the premacular vitreous, peripheral cortical vitreous and mid-vitreous were all below the detection limit (<20 pg/mL).

In DME, vitreous VEGF concentration correlates with mean foveal thickness measured on OCT. VEGF concentration was higher in premacular vitreous than in mid-vitreous and peripheral cortical vitreous, suggesting diffusion from the macular region to the periphery, and from the posterior to the anterior globe.