Diabetic Retinopathy

Question 1

What is diabetic retinopathy?

Answer 1

Diabetic retinopathy is the retinal consequence of chronic progressive diabetic microvascular leakage and occlusion. It eventually occurs to some degree in all patients with diabetes mellitus.

Question 2

Briefly describe the classification of diabetic retinopathy

Answer 2

Diabetic retinopathy can be split into two broad categories: non-proliferative and proliferative depending on whether new blood vessels have developed. Non-proliferative is often called background or pre-proliferative retinopathy as it can develop in to proliferative retinopathy. A condition called diabetic maculopathy also exists separate from non-proliferative and proliferative diabetic retinopathy.

These conditions are classified based on the findings on fundus examination.

Question 3

Briefly recap the anatomy of the normal fundus

Answer 3

Question 4

Briefly describe the pathophysiology of diabetic retinopathy

Answer 4

Hyperglycaemia leads to damage to the retinal small vessels and endothelial cells. Increased vascular permeability leads to leakage from the blood vessels, blot haemorrhages and the formation of hard exudates. Hard exudates are yellow/white deposits of lipids in the retina.

Damage to the blood vessel walls leads to microaneurysms and venous beading. Microaneurysms are where weakness in the wall causes small bulges. Venous beading is where the walls of the veins are no longer straight and parallel and look more like a string of beads or sausages.

Damage to nerve fibres in the retina causes fluffy white patches to form on the retina called cotton wool spots.

Intraretinal microvascular abnormalities (IMRA) is where there are dilated and tortuous capillaries in the retina. These can act as a shunt between the arterial and venous vessels in the retina.

Neovascularisation is when growth factors are released in the retina causing the development of new blood vessels.

Question 5

What is shown in the image?

Answer 5

Cotton wool spots on fundoscopy.

Question 6

What is shown in the image?

Answer 6

Flame shape haemorrhages on fundoscopy.

Question 7

What is shown in the image?

Answer 7

Blot haemorrhages on fundoscopy.

Question 8

What is shown in the image?

Answer 8

Intraretinal microvascular abnormality (IMRA) on fundoscopy.

Question 9

What are the featurs of mild, moderate and severe non-proliferative diabetic retinopathy?

Answer 9

Mild: microaneurysms.

Moderate: microaneurysms, blot haemorhages, hard exudates, cotton wool spots and venous beading.

Severe: blot haemorrhages plus microaneurysms in 4 quadrants, venous beating in 2 quadrates, intraretinal microvascular abnormality (IMRA) in any quadrant.

Question 10

What are the features of proliferative diabetic retinopathy?

Answer 10

• Neovascularisation
• Vitreous haemorrhage

Question 11

What are the features of diabetic maculopathy?

Answer 11

• Macular oedema
• Ischaemic maculopathy

Question 12

What are the risk factors for diabetic retinopathy?

Answer 12

• Young onset diabetes
• Longer duration of diabetes
• Poor glycaemic control
• Hypertension
• Renal disease

Question 13

What investigations should be ordered for diabetic retinopathy?

Answer 13

• Photographs of the fundus
• Optical coherence tomography scanning
• Fluorescein angiography

Question 14

Briefly describe the management of diabetic retinopathy

Answer 14

• Laser photocoagulation
• Anti-VEGF medications such as ranibizumab and bevacizumab
• Vitreoretinal surgery (keyhole surgery on the eye) may be required in severe disease

Question 15

What are the complications of diabetic retinopathy?

Answer 15

• Retinal detachment
• Vitreous haemorrhage (bleeding in to the vitreous humour)
• Rebeosis iridis (new blood vessel formation in the iris)
• Optic neuropathy
• Cataracts

Question 16

What differentials should be considered for diabetic retinopathy?

Answer 16

• Ocular ischaemic syndrome
• Radiation retinotherapy
• Retinal venous occlusion
• Hypertension