Characterization of Early Stages of Diabetic Retinopathy: Importance of the Breakdown of the Blood-Retinal Barrier

I n an excellent clinical overview on diabetic retinopathy, Davis (1) describes the natural course of diabetic retinopathy, considering the presence of retinal capillary microaneurysms as the earliest reliable sign. He affirms that "when the number of microaneurysms in an eye exceeds 10, fluorescein angiography usually demonstrates retinal capillary abnormalities, consisting of capillary dilatation, capillary nonperfusion (capillary dropout), and/or focal fluorescein leakage from microaneurysms or more diffuse leakage from capillaries (1)."