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

Table 2 Early treatment of diabetic retinopathy classification of diabetic retinopathy

Category	Features	Follow-up periods
No DR	No findings	12 months
Very mild NPDR	Microaneurysms only	Most of the patients in 12 months
Mild NPDR	Any or all of: Microaneurysms, retinal hemorrhages, exudates, cotton wool spots	6-12 months, depending on the severity of signs, stability, systemic factors, and patient’s personal circumstances
Moderate NPDR	Severe retinal hemorrhages in 1-3 quadrants or mild IRMA; Significant venous beading in no more than one quadrant; Cotton wool spots	Approximately 6 months (PDR in up to 26%, high-risk PDR in up to 8% within a year)
Severe NPDR	The 4-2-1 rule; Severe retinal hemorrhages in all four quadrants; Significant venous beading in ≥ 2 quadrants; Moderate IRMA in > 1 quadrant	4 months (PDR in up to 50%, High-risk PDR in up to 15% within a year)
Very severe NPDR	≥ 2 of the criteria for severe	2-3 months (high-risk PDR in up to 45% within a year)
High-risk PDR	NVD > 1/3rd disc area; Any NVD with vitreous/Pre-retinal hemorrhage; NVE > 1/2 disc area with vitreous/pre-retinal hemorrhage	Laser photocoagulation Intravitreal Anti-VEGF agents Intravitreal Triamcinolone Pars Plana Vitrectomy; Lipid-lowering drugs
Advanced diabetic eye disease	Pre-retinal (retro hyaloid) and/or intragel hemorrhage; Tractional retinal detachment Tractional retinoschisis Rubeosis Iridis (Iris Neovascularization)	Pars plana vitrectomy

NPDR: Non-proliferative diabetic retinopathy; NVD: Neovascularization of the disc; NVE: Neovascularization elsewhere; PDR: Proliferative diabetic retinopathy.