Table 1.

Main mechanisms of action of the most representative topical treatments (eye drops) for early stages of DR in experimental models.

Treatment	Reference	Neuro- degeneration	Micro- angiopathy	Mechanisms of Action
				Glial Inflammation	Neuronal Apoptosis	Oxidative Stress	Vascular Permeability
PEDF	[91]	yes	yes	+	+		+
SST	[59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104]	yes		+	+
GLP-1	[60,112, 113]	yes	yes	+	+	+	+
DPP-IVi	[118]	yes	yes	+	+	+	+
Bosentan	[61]	yes	yes	+	+		+
SOCS-1	[126]	yes	yes	+	+		+

PEDF: pigment epithelium-derived factor; SST: somatostatin; GLP-1: glucagon-like derived peptide 1; DPP-IVi: dipeptidyl peptidase IV inhibitors; SOCS-1: suppressors of cytokine signaling-1.