Diabetic Retinopathy

Question 1

Definition of diabetic retinopathy:

Answer 1

Is an example of a microvascular complication of diabetes mellitus, occurs as a result of leakage and occlusion

Question 2

Aetiology of diabetic retinopathy

Answer 2

The main cause is hyperglycaemia as it can have an impact on blood composition, blood vessel walls and blood flow.
• These changes would result in retinal capillary leakage and non-perfusion
◦ This can then cause tissue hypoxia and may then affect non-vascular retinal tissue

• Other important factors to consider are:
◦ Hypertension
◦ Genetic factors

There are 3 main types:
‣ Background retinopathy

				‣ Pre-proliferation retinopathy: Earlier stage of disease, less severe (blood vessels in eye leak fluid into retina)

				‣ Proliferative retinopathy: More severe stage of disease, new blood vessels start to form on the retina (which are fragile and can haemorrhage). This can cause vision loss and scarring of the retina

				‣ Maculopathy:

Question 3

Pathophysiology of diabetic retinopathy

Answer 3

• Retinal capillary leakage would give rise to:
◦ Intraretinal haemorrhage
◦ Cholesterol exudate deposition
◦ Retinal oedema
◦ Macula involvement (affecting central vision)

Retinal capillary occlusion can lead to:
◦ Micro aneurysms
◦ Cotton wool spots
◦ Development of new retinal vessels and hence risk of haemorrhage

• There is an increased VEGF expression induced by hypoxia
◦ It’s release promotes retinal capillary permeability
◦ Acts as a therapeutic target

Question 4

History and Examination for diabetic retinopathy

Answer 4

• Background retinopathy:
• Hard exudates (cheese colour, represents lipid deposition)
• Microaneurysms (dots)
• Blot haemorrhages

• Pre-proliferate retinopathy:
• Cotton wool spots (soft exudates)
• These are signs of retinal ischaemia

• Proliferative retinopathy:
• Visible new vessels due to hypoxia, BUT easily fixable and can haemorrhage

• Maculopathy:
• Hard exudates/oedema near the macula
• Same disease as background retinopathy, but occurs near the macula
• Can threaten vision

• Vision loss: may be acute or gradual

Question 5

Risk factors of diabetic retinopathy

Answer 5

• longer duration diabetes
• Poor glycaemic control
• Hypertension
• Renal disease
• Young onset diabetes

Question 6

Investigations for diabetic retinopathy

Answer 6

• Yearly retinopathy screening: In order to detect retinopathy early in its asymptomatic stage so that it can be treated before it causes visual disturbance/loss
• Photographs of fundus

Question 7

Treatment of diabetic retinopathy

Answer 7

Background retinopathy:
1) Continued annual surveillance + Manage glycaemic and BP control

Pre-Proliferative retinopathy:
1) Early Panretinal photocoagulation + Management of glycaemic and BP control: Burn through damaged areas to prevent angiogenesis and reduce the risk of haemorrhage, BUT can affect peripheral vision

Proliferative retinopathy:
1)Panretinal retinopathy

Diabetic maculopathy:
1) Anti-VEGF injections directly into the eye to treat any oedema
Grid Photocoagulation

Question 8

Prevention and prognosis of diabetic retinopathy

Answer 8

• Optimum control of blood pressure and glucose can delay the onset and progression of diabetic retinopathy

Is a chronic and progressive disease
There may be risk of recurrence, however the chance of haemorrhage decreases in those who have been treated with Panretinal photocoagulation as opposed to those who haven’t

Question 9

Complications of diabetic retinopathy

Answer 9

• Cataracts: diabetic retinopathy greatly increases the risk of developing cataracts
• Panretinal photocoagulation side effect: macular oedema, visual field loss etc