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)

Pathophysiology

1. Hyperglycemia results in glucose being metabolised by alternative pathways DR patients - result in oxidative stress and inflammation

2. Causes blood vessels, including those supplying the retina, to weaken and rupture; the vessel walls may dilate resulting in microaneurysms or small haemorrhages

3. 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

4. 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

5. Neovascularization into the vitreous humour may culminate in widespread vitreous haemorrhage causing sudden and complete visual loss

6. Fibrovascular bundles can lead to fibrosis and, in turn, retinal traction, which can result in retinal detachment and recurrent vitreous haemorrhage

Non-proliferative diabetic retinopathy (NPDR)

Mild-moderate

• Microaneurysms

• Hard exudates

• Intraretinal haemorrhages

• Cotton wool spots - caused by ischaemia

• Patients may be asymptomatic

Microaneurysms and hard exudates

Haemorrhages

Cotton wool spots

Venous bleeding

Proliferative diabetic retinopathy

• Neovascularisation

• Vitreous haemorrhage and traction

Clinical features of vitreous haemorrhage

• Floaters

• Severe visual loss

• Requires opthalmologic consultation

Diabetic macular oedema

• Characterised by oedematous changes in or around the macula

Management of diabetic eye disease

• Laser therapy
• Focal macular laser for clinically significant macular oedema (CSME)
• Panretinal photocoagulation for PDR

• Vitrectomy
• May be necessary for vitreous haemorrhage or retinal detachment
• Used in patients with diabetic macular oedema with clinical or OCT signs of traction

• Anti-VEGF agents used in macular oedema - decrease capillary permeability and angiogenesis