diabetic eye disease

Diabetes can manifest itself through several ophthalmic conditions, grouped under the term diabetic eye disease
Can be classified clinically into non-proliferative (NPDR) and proliferative (PDR) forms, according to the presence or absence of retinal neovascularization, and it can present with or without macular edema (DME)
Diabetics should undergo yearly retinal screening

Pathophysiology

Hyperglycaemia results in glucose being metabolised by alternative pathways DR patients - result in oxidative stress and inflammation
Causes blood vessels, including those supplying the retina, to weaken and rupture; the vessel walls may dilate resulting in microaneurysms or small haemorrhages
The damaged pericytes and erythrocytes increase vascular permeability - lipoproteins, lipids and other products carried by blood are therefore able to leak out and cluster onto the retina as hard exudates
As blood flow becomes increasingly compromised, regions of the retina are starved of oxygen - vascular endothelial growth factor (VEGF) is released in response to the hypoxia to promote neovascularization but the new vessels are poorly formed and easily rupture resulting in bleeding
Neovascularization into the vitreous humour may culminate in widespread vitreous haemorrhage causing sudden and complete visual loss
Fibrovascular bundles can lead to fibrosis and, in turn, retinal traction, which can result in retinal detachment and recurrent vitreous haemorrhage

Early stages of retinopathy, rated from mild-severe (with severe being last stage before proliferative retinopathy)
Damage to the wall of small vessels cause microaneurysms and then intraretinal haemorrhages (dot, blot, flame)
Leaked blood leaves behind hard exudates (lipid breakdown products)
Micro-infarcts (ischaemia) due to occluded vessels cause cotton wool spots
Laser therapy in severe NPDR may help prevent long-term visual loss

Microaneurysms and hard exudates

Haemorrhages

Cotton wool spots

Venous bleeding