Diabetic retinopathy: A review on its pathophysiology and novel treatment modalities

Table 4 International clinical diabetic retinopathy disease severity scale classification of diabetic retinopathy

Disease
Concerning diabetic retinopathy
No apparent retinopathy	No findings
Mild NPDR	Only microaneurysms
Moderate NPDR	More microaneurysms and less than severe disease
Severe NPDR	No signs of PDR; Intraretinal hemorrhages in all four quadrants; Venous beading in ≥ 2 quadrants; Prominent IRMA ≥ 1 quadrant
PDR	Neovascularization; Vitreous or subhyaloid hemorrhage Figure 6 (Fundus picture showing PDR)
Concerning DME
DME apparently absent	No retinal thickening and hard exudates at the posterior
DME apparently present	Apparent retinal thickening and hard exudates present at the posterior pole. Furthermore, it can be classified into three subtypes based on the area of thickening and hard exudates in the center of the Fovea
Mild DME	The retinal thickening or hard exudates are located farther away from the center of the fovea
Moderate DME	Retinal thickening or hard exudates are near the center of the macula but not involving the fovea
Severe DME	Hard exudate and thickening present in the center of the fovea

DME: Diabetic macular edema; NPDR: Non-proliferative diabetic retinopathy; PDR: Proliferative diabetic retinopathy.