Diabetic macular edema. Clinical characterization

Abstract

The most frequent cause of progressive visual loss due to diabetes is diabetic macular edema. There is retinal edema when there is any increase of water in the retinal tissue resulting in an increase in its volume, i.e., thickness. In diabetes, the inner Blood-Retinal Barrier (BRB) opens resulting in increasing movements of fluids and molecules into the retina. In a situation of open BRB there is extracellular retinal edema and the situation of immune privilege is altered, creating the conditions for a systemic inflammatory repair response. When the BRB is open, the retinal edema accumulation follows Starling's law. With an open BRB any loss of equilibrium between hydrostatic, oncotic and tissue pressure gradients across the retinal vessels contribute to increased water movements and more edema formation. We are able to measure changes in retinal thickness and identify, using OCT, the evolution of macular edema. It is possible to follow closely changes in retinal edema and to characterize diabetic macular edema considering: 1. The distribution of the edema. Is it focal or diffuse? 2. Is it recent or chronic? 3. Is the foveola preserved or is it involved and how much? 4. Is the BRB open (vascular leakage)? 5. Are there signs of retinal pigment epithelium (RPE) dysfunction? Diffuse edema with RPE signs of damage? 6. Are there OCT "cysts"? A good indicator of low tissue pressure. 7. Are there signs of vitreoretinal traction on OCT? 8. Are there signs of capillary closure and ischemia in the fovea? 9. Are HgA1C values higher than 8%? 10. Is the blood pressure higher than 130/80mm/Hg even after medication?